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During an annual “well-woman” visit, it is customary to perform a pelvic exam to screen for cancers of the reproductive system. These cancers include uterine cancer, ovarian cancer, and cervical [Origin: Latin, cervix (neck)] cancer. The last one is especially noteworthy, thanks to the development and implementation of the most successful cancer screening test in medical history: the Pap test. This screening test swabs the cervix of the uterus and assesses the morphology of the obtained cells. If the cells are atypical, the gynecologist obtains a cervical biopsy to further assess the situation and take the appropriate measures.

What is the etymology of “Pap” in “Pap test?” Turns out that this is not from an ancient Greek root; rather, it’s from a modern Greek physician! Georgios Papanikalaou (1883-1962) drew inspiration from Walter Hayle Walsh (1812-1892) when the latter reported on the observation of malignant cells under the microscope in certain lung diseases. In 1928, Papanikalaou presented his technique to an audience of physicians:

  1. Gather cellular debris from the vaginal tract
  2. Mount it on a microscope slide
  3. Stain it with the Pap stain (haematoxylin counterstained with OG-6 and eosin azure)

Left: Georgios Papanikalaou, right: Aurel Babeş

Even though Papanikalaou first developed and demonstrated the use of this technique, it turns out that another physician—Aurel Babeş—made similar progress regarding the microscopic analysis of malignant cells. Babeş used a platinum loop to collect cells from the cervix and mounted the sample on a microscope slide. Babeş published before Papanikalaou, but Papanikalaou used the technique in hospitals before Babeş published. For this reason, we give it the name of “Pap test,” but in Romania, it is called the “Babeş-Papanikalaou test” in honour of Babeş’s independently-developed method. In Spanish, the “Pap” is said in full, i.e., it is “la prueba de Papanikalaou”: the test/probing of Papanikalaou!

There is another gynecologic eponym [Origin: Greek, epi- (on/upon) + onoma (name)] that most people don’t readily recognize. Gabrielle Falloppio (1523-1562) was an Italian physician and anatomist who primarily explored the anatomy of the head: he described the inner ear, the middle ear, the mastoid cells, and the circular & oval windows, among many other structures. He also studied the reproductive systems of both males and females—including the structures that connect the ovaries to the uterus. For those that prefer non-eponymous nomenclature, an alternative name for the Fallopian tubes is uterine tubes. Note that Falloppio’s name is spelled with 2 “p”s, but we only use one “p” in Fallopian! (In Spanish, it is cut down by an extra “l,” spelled “Falopio.”) Falloppio also advocated the use of condoms to prevent syphilis and conducted an early clinical trial of sorts; he observed that the approximately 1100 men who used condoms and reported to him did not contract syphilis.

Left: Gabriele Falloppio, right: a 16th century prophylactic device

If the Fallopian tubes and the ovaries are afflicted with cancer and need to be removed, what words do we use to describe the surgery? For the Fallopian tubes, we use salpingectomy, and for the ovaries, we use oophorectomy.

Salpingectomy
Origin: Greek, salpinx (trumpet) + ek- (out of) + temnein (to cut) + -ia (condition of)
A cutting out of the trumpet, i.e., the Fallopian/uterine tube
N.B. (nota bene): in Spanish, they are called “las trompas de Falopio”: tube/horn of Falloppio!

Oophorectomy
Origin: Greek, oion (egg) + pherein (to carry) + -ectomy (a cutting out)
A cutting out of the egg-carrier, i.e., the ovary

And if both entities need to be removed, we call it a salpingo-oophorectomy. This term denotes that only one ovary and one Fallopian tube is excised; if both are excised, we append bilateral [Origin: Latin, bi- (two) + latus (side)] to the procedure for a bilateral salpingo-oophorectomy.

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Animals were of prime importance in the classical world: agriculture in the Roman Empire depended on domesticated oxen (L., bos) to plow the fields, crowds of thousands cheered on the races at the Circus Maximus, as drivers atop their chariots urged on the fastest horses (L., equus) in the land, and sacrifices of sheep (L., ovis), and pigs (L., porcus) were necessary to please the gods. So too were animals important to ancient scientists and physicians. It was the dissection of and the experiments on animals that formed the basis for early understanding of human anatomy and physiology. In addition, there are countless anatomic terms whose etymologies derive from the Greek and Latin names of animals.

Cauda equina
Origin: Latin, cauda (tail) + equus (horse)
Horse’s tail

cauda equina

Sitting within and protected by the vertebral column, the spinal cord consists of nerve cells and their extensive myelinated tracts that carry motor, sensory, and autonomic data to and from the brain. One would think that the spinal cord extends all the way to the bottom of the vertebral column, but in fact it stops looking like a cord at the level of the L2 vertebra in adults. At that point, it gives rise to the so-called cauda equina where individual nerves arising from the lower part of the spinal cord descend down the vertebral column until they exit through the proper foramina. It’s no wonder then why lumbar punctures must be done below L2: the individual nerves of the cauda equina can easily accommodate the lumbar puncture needle unlike the large-diameter spinal cord. So the next time you consent a patient for an LP, be sure to ask yea or neigh.

Coccyx
Origin: Greek, kokkux (cuckoo)

sacrum

The vertebral column consists of seven cervical, twelve thoracic, and five lumbar vertebrae. The primary role of these bones is to protect the spinal cord. However, their articulations allow flexion, extension, lateral motion, and rotation of the back, explaining their derivation from vertere (L., to turn). There are two more bones that lie below L5. The sacrum, which the Romans called the os sacrum (L., sacred bone) and which the Greeks named the hieron osteon (Gk., sacred bone), sits within the pelvis and allows the sacral nerves of the cauda equina to exit through its foramina. It’s not clear why this bone was considered “sacred.” One thought is that its sacredness derives from its location in the pelvis and therefore an association with reproduction. Another theory suggests that the ancients used this bone during sacrificial ceremonies. Finally, below the sacrum sits the coccyx, the small bony remnant of a vestigial tail. The ancient anatomists who named this bone thought that, when viewed from its side, it bears resemblance to a cuckoo’s beak.

Tragus
Origin: Greek, tragos (goat)

traigus

The tragus is that small piece of cartilaginous tissue situated next to the opening of the ear canal. And for some strange reason, it’s derived from the Greek word for goat. Perhaps some Greek anatomist had particularly hairy ears and thought it resembled the hair on a goat’s chin. Whatever the reason, the association with goats definitely stuck: the medical term describing hair on the ears is barbula hirci, literally meaning “little beard of the goat” [L., barbus (beard) + hircus (goat)]. No kidding.

Concha
Origin: Greek, konkhe (mussel, shell)

concha

Within the nose lie the superior, middle, and inferior nasal conchae. These long shelves of bone on the lateral aspects of the nasal cavity are covered with mucosa and supplied by a rich network of blood vessels. Their most important function is to warm and humidify the air as it passes from the nasal cavity to the lungs. If I look really hard, I can make myself believe they look like little mussels. Astute readers will notice that concha also appears in the labeled anatomy of the outer ear: concha also describes the fossa next to the opening to the ear canal.

Pes Anserinus
Origin: Latin, pes (foot) + anser (goose)
Goose’s foot

pes anserinus

Three muscles of the leg, the gracilis [L., gracilis (slender)], sartorius [L., sartor (tailor)], and semitendinosus [L., semi (half) + tendere (to stretch)], give rise to tendons that travel in parallel before attaching to the same location on the tibia. The ancient anatomists who saw this arrangement must have been reminded of the tripartite webbed feet of the goose and named it as such. There is a clinical condition called “pes anserinus pain syndrome,” also known as “pes anserine bursitis,” that describes pain around these tendons on the medial side of the knee. Interestingly enough, pes anserinus is not only a structure in the leg: it also is another name for the parotid plexus, where the facial nerve branches after exiting the stylomastoid foramen.

Recurrent Laryngeal Nerve

galen dissection

Galen demonstrating the effects of the recurrent laryngeal nerve during the dissection of a pig

The recurrent laryngeal nerves are branches of the vagus nerves that control nearly all of the intrinsic muscles of the voice box. Therefore, injury to one or both may cause hoarseness or even a complete inability to phonate. The etymology is nothing to write home about, but the story of their discovery definitely is. The famed Greek physician Galen, while conducting an experiment on a live, strapped-down pig, accidentally cut both laryngeal nerves; the pig continued to struggle but completely stopped squealing. He ultimately traced out the path of the nerves and confirmed that they originated from the vagus nerves. He noted that “there is a hairlike pair [of nerves] in the muscles of the larynx on both left and right, which if ligated or cut render the animal speechless without damaging either its life or functional activity.” Galen held a public demonstration of his experiment in Rome that was well-attended by distinguished politicians and scholars of the time. Those readers interested in learning more can read the article “Galen and the Squealing Pig,” linked here.

Thanks for taking a trip to the zoo with me. I’m off to see the capybara exhibit.

P.S.: Can you think of the English adjectives derived from the Latin words mentioned in the first paragraph? As a bonus, what about the adjective that describe wolves? Fish? Ducks?

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When we think of the deadliest diseases of the world, things like Ebola and the Black Death come to our minds. However, it turns out that cardiovascular disease (CVD) is the world’s leading cause of death in this day and age. In the 1970s, we were convinced that CVD was caused by dietary fat. Indeed, there was a public campaign to stamp out fat and replace it with carbohydrates. People didn’t realize that fat wasn’t the issue. Rather, fat has the highest calorie/mass ratio (9 calories per gram) and excess consumption of fat leads to obesity and its milieu of problems, including CVD. The food industry replaced fat with carbohydrates to meet this craze, and “fat-free” foods were instead pumped with sugar. Of course, calories are calories—and when people consumed these foods in earnest, not much changed with regards to the incidence of CVD.

So what exactly is fat? Chemically, fat is a glycerol molecule + three fatty acids. Fatty acids are long-chained aliphatic carboxylic acids that are either saturated (only single bonds) or unsaturated (one or more double/triple bonds). Quick aside: in popular culture, we hear about “omega-3 fatty acids” and “omega-6 fatty acids.” This refers to the position of the first double bond in the fatty acid, with the omega position being the last carbon in the chain (see picture below). So an omega-3 fatty acid is a fatty acid that has its first double bond on the 3rd carbon from the omega position.

Glycerol
Origin: Greek, glykeros (sweet) + –ol (chemical suffix for alcohols)
So named because glycerol is, in fact, sweet (and is an alcohol)

triglyceride glycerol

Aliphatic
Origin: Greek, aleiphar (oil)
Refers to hydrocarbons that do not contain benzene rings

What about the term lipid [Gk. lipos (fat)]? In the vernacular, people equate the word “lipid” to “fat,” and its etymology certainly vindicates such an equation. But of course, we must be rigorous with our definitions. To start, fats (i.e., triglycerides) are certainly a lipid subclass. Other subclasses include waxes (fatty acid esters such as beeswax; article’s featured image) and sterols (isoprene-derived steroids such as cholesterol). One classical definition of a lipid is the following: lipids are hydrophobic (some also include amphiphilic) small molecules that can dissolve in organic solvents but not water.

Hydrophobic
Origin: Greek, hydor (water) + phobos (fear)
Fear of water, i.e., not dissolvable in water or other polar solvents

Amphiphilic
Origin: Greek, amphi – (both) + philia (love)
Love of both water and fat, i.e., dissolvable in polar and nonpolar solvents

For those who love math, recall that for a statement to be proven true, it must be true in all instances. For a statement to be proven false, one need only provide a counterexample. So my counterexample for this definition of lipid is the molecule carbon tetrachloride (CCl4). CCl4 is a small molecule, it is hydrophobic, it dissolves in organic solvents, and it doesn’t dissolve in water. Now, to patch the definition up, one can make an addendum to include “naturally-occurring.” Needless to say, CCl4 is not naturally-occurring. Is there another definition of lipid that you prefer? Let me know in the comments!

lipids

Before ending this post, I would like to touch on the significance of fat in disease. There are a number of disease states that manifest with malabsorption; one of them is coeliac disease. The diarrhea that coeliac patients experience after ingesting gluten is more accurately termed steatorrhea:

Steatorrhea
Origin: Greek, stear (fat) + rhein (to flow)
Flow of fat (through the intestines), i.e., fat in the stools

How can you identify steatorrhea? If the stool is especially foul-smelling and sticks to the sides of the porcelain shrine, you’ve got yourself a flow of fat.

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Pneumonia is one of those medical conditions that is constantly thrown around without being rigorously defined—and as we all know by now, rigor is absolutely paramount in my view of academic medicine and medical etymology. Let’s start by looking at the word from an etymological standpoint:

Pneumonia
Origin: Greek, pneumon (lung) + –ia (condition of)
Condition of the lung

Well, that certainly wasn’t very helpful—at least not at first glance. There can be many conditions of the lung that are called “pneumonia” and the classic case of a lung infection is merely one of them. Compare pneumonia to pneumonitis:

Pneumonitis
Origin: Greek, pneumon (lung) + -itis (inflammation of)
Inflammation of the lung

There are many inflammatory conditions of the lung, but only a few of them are called “pneumonitis” because pneumonitis is considered to be inflammation of the lung tissue itself (the lung parenchyma). There are some who then consider pneumonia to be inflammation of the air sacs in the lungs (the alveoli). This makes sense for the most part; the bacteria, viruses, fungi, and parasites that can cause pneumonia would cause alveolar inflammation.

lung diagram

To put things in perspective, when somebody is admitted to the hospital for pneumonia, the classic picture is someone who acquires a bug, and said bug colonizes the alveolar space. The resulting “mass” that forms (usually in one lobe of the lung) is called a consolidation:

Consolidation
Origin: Latin, con- (with) + solidus (solid)
With solid, i.e., things that aggregate to form a “solid”

For these “classic” pneumonias, we can call them community-acquired pneumonia (CAP), hospital-acquired pneumonia (HAP), and the like. Some bugs associated with the former are things like Streptococcus pneumonia and Pseudomonas aeruginosa, and some bugs associated with the latter are things like Staphylococcus aureus and Haemophilus influenzae. (Stay posted for microbiological etymology!)

But it turns out that this isn’t the whole picture. Pneumonia is indeed as general as its etymology suggests, for there can be inflammatory and fibrotic conditions of the lung—and both classes can fall under the term “pneumonia.” (Generally, inflammation is caused by the infiltration of white blood cells and fibrosis is caused by the production of excess connective tissue, e.g., collagen.) Thus, as a counterexample to the definition that pneumonia is simply the inflammation of the alveoli, we have something called usual interstitial pneumonia (UIP). It is a form of interstitial lung disease in which the tissue between the alveoli is fibrosed with collagen.

uip ctThe classic “honeycomb lung” appearance of UIP on CT scan

To end this post, I posit my generalized definition of pneumonia: pneumonia is a principally inflammatory or fibrotic condition of the lung. By formalizing this definition of pneumonia, I am faithful to the etymology and make pneumonitis a subset of pneumonia. Note that I use the word “principally” in front of inflammatory—the reason why is that cancers of the lung can cause inflammation, but cancers are not considered to be pneumonias by any definition or practice.

In another post I will discuss the classic methods of diagnosing “normal” (generally bacterial) pneumonia and the etymologies of these techniques. Here is a small teaser: one of the terms involves the Greek word for goat! Can you guess which one? Leave a comment below.

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There are a number of ways of diagnosing disease: tissue biopsy, symptom matching, and of course, clinical signs. People often use the latter two terms interchangeably, especially since they are often paired together via the phrase “signs and symptoms.” But rigorously, these two words refer to two different things. Perhaps their etymologies will help differentiate them:

Sign
Origin: Latin, signum (sign/image)
Something the clinician notes in during a clinical encounter

Symptom
Origin: Greek, sym- (together) + piptein (to fall)
Something a patient reports to the clinician; something that “falls together” with something else

In other words, symptoms are subjective experiences while signs are objective experiences. For example, if I tell my doctor I have a fever, that is considered a symptom, but if he or she were to measure my temperature and find it elevated, it would be a sign. Another good example: pain is a symptom, since the perception of pain is unique to each patient. Tenderness, however, is a sign, since it is elicited by a clinician, e.g., applying pressure to the abdomen and eliciting an “ouch!”

stigmata rev

St. Francis Receives the Stigmata, by Antoni Viladomat (1678-1755)

There is another pair of terms that are often used together that is also often conflated. These words are stigma (plural stigmata) and sequela (plural sequelae). A stigma is a readily-visible (cutaneous or otherwise) or discernable sign that is characteristic of some disease. A classic stigma of liver disease is jaundice.A sequela, on the other hand, is an abnormal state or complication that results from a previous disease. A classic sequela of diabetes is diabetic nephrophaty. The etymologies of these words are relatively straight-forward:

Stigma
Origin: Greek, stizein (to mark/tattoo)

Sequela
Origin: Latin, sequi (I follow)

Interestingly enough, the word “stigmata” is also used in theology to refer to the bodily marks or sensations of pain associated with the crucifixion [Origin: Latin, crux (cross) + figere (to fix/bind)] of Jesus. Those who bear these stigmata are called “stigmatics” or “stigmatists,” and a common motif in classical painting is St. Francis of Assisi’s reception of the stigmata (see above). St. Francis supposedly received the stigmata of Christ for his great piety during the Feast of the Exaltation of the Cross after a forty-day fast.

Regarding jaundice, a stigma of liver disease, we know it to be the yellowing of the skin due to increased levels of bilirubin. Jaundice can, of course, be caused by a number of other conditions, e.g., deficiencies in certain enzymes (cf. Gilbert syndrome). There is one part of the body that is not said to be jaundiced when yellow; that honour falls on the eyes. When the eyes turn yellow due to, say, liver disease, we call it scleral icterus.

icterus rev

Jaundice
Origin: Latin, galbinus (yellow/yellow-green)

Icterus
Origin: Greek, ikteros
A bird said to cure jaundice when spotted

Hence we call it scleral icterus because it is with our eyes that we see the ikteros and become cured of our jaundice!

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I think it’s safe to say that we’re all fairly familiar with our five senses: seeing, hearing, touching, tasting, and smelling. But what self-respecting etymology blog calls it a day with those terms? We need to be more rigorous!

sight                →   vision          →       Latin, videre (to see)
hearing           →   audition      →        Latin, audire (to hear)
touch              →   taction        →        Latin, tangere (to touch)
taste               →   gustation    →        Latin, gustare (to taste)
smell               →   olfaction     →       Latin, olfacere (to smell)

There are even fancier terms for these, such as ophthalmoception, but let’s not get too carried away.

Ophthalmoception
Origin: Neo-Latin, ophthalmos (Gk. eye) + recipere (L. to receive)
To receive from the eye, i.e., vision

Bruegel_d._Ä.,_Jan_-_Allegory_of_Sight_and_Smell_-_1618

The Sense of Sight and Smell, by Brueghel the Elder

Without getting into fantastical and/or esoteric discussions of the legendary sixth sense, it turns out that we have much more than five senses. These “nontraditional senses” depend on special receptors in our bodies, and some of them don’t rely on specific sensory apparatus (singular: apparatus) (no, that’s not a joke). One classic example is proprioception, which is the ability to know where one’s body is in three-dimensional space. Unconscious proprioception relies on the cerebellum, whereas conscious proprioception relies on the dorsal column/medial lemniscus (DCML) tract to the parietal lobe.

Proprioception
Origin: Latin, proprius (one’s own) + -recipere (to receive)
To receive one’s own, i.e., information about one’s own body

What about the sensation of pain? Pain is a complex topic and much research has gone into it. Our current understanding of pain is that pain is not directly sensed by the body; rather, it is “interpreted” by the body after exposure to a noxious stimulus. Noxious stimuli stimulate peripheral nerves and the central nervous system generates pain. The detection of noxious stimuli is done via nociception by nociceptors.

Nociception
Origin: Latin, nocere (to hurt/harm) + recipere (to receive)
To receive hurting/harm, taken to mean pain

Again, rigorously, our bodies to do not directly sense pain—they sense noxious stimuli, and develop pain in response. Also note that it is difficult to assign a definition to pain, for it is a subjective phenomenon: we all respond to noxious stimuli differently.

descartes rev

Descartes thought that animals lacked consciousness—and thus could not feel pain

I was given a request for the adjective forms of some of the nontraditional senses, but I couldn’t find many of them in any dictionaries. I did find the adjective form for proprioception: proprioceptive. Using this convention, here is a list of adjectives:

proprioception             →        proprioceptive
nociception                  →        nociceptive
chronoception             →        chronoceptive
thermoception             →        thermoceptive

I haven’t discussed the last two terms on this list; what are their etymologies? Leave a comment below with your answer!

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In the medical field, there is a consistent misuse of the words hypertrophy and hyperplasia. It’s not quite as egregious as the misuse of the suffix “-itis,” but it is still saddening—at least to me. An etymological breakdown can help us differentiate between the two terms:

Hypertrophy
Origin: Greek, hyper (over/above) + trephein (to feed)
To overfeed ; taken to mean an increase in cell size

Hyperplasia
Origin: Greek, hyper (over/above) + plassein (to mould)
To mould over; taken to mean an increase in cell number

These are the definitions on the cellular level, but it turns out that some pathologists also use the term hypertrophy to denote a gross increase in organ size, hence the confusion. For example, when a man’s prostate becomes enlarged, it is due to hyperplasia (an increase in cell number). The cellular term for this phenomenon is nodular hyperplasia. On an autopsy report, however, a pathologist would report it as prostatic hypertrophy because he or she can see the increase in size through the naked eye. Hyperplasia is a normal physiological response and it is not pathologic. A good example is the hyperplasia of the uterine lining (the endometrium) in the menstrual cycle.

hyperplasia comparison rev

Note, however, that the story with hyperplasia is a bit more nuanced than that. In the case of the endometrium [Origin: Greek, endo- (in) + metron (womb)], physiologic hyperplasia is termed “simple hyperplasia without atypia.” The term simple vs. complex denotes that the cells either have or have not proliferated to the point of interfering with the normal architecture of the endometrium. The modifier of “atypia” denotes a structural abnormality of the cells; thus, atypical cells can be considered to be dysplastic.

This brings us to another pair of -plasias that is often confusing to people: neoplasia vs. dysplasia. The difference between these two terms is a bit more subtle, but again, some etymology may be of use to us.

Neoplasia
Origin: Greek, neo– (new) + plassein (to mould)
A new moulding; taken to mean an abnormal proliferation of cells (either benign or malignant)

Dysplasia
Origin: Greek, dys– (ill) + plassein (to mould)
An ill molding; taken to mean an increased number of immature cells (compared to regular cells) and greater variability between cells

On a functional basis, dysplasia may progress to neoplasia, but dysplasia by itself doesn’t denote an abnormal growth or increase in cell number. Indeed, dysplasia results in an increased ratio of immature to mature cells and variability because it has acquired just enough mutations to appear odd—hence, depending on the situation, its progression to neoplasia. One might then ask: “What about carcinoma in situ (CIS)?” Well, dear reader, CIS is a subset of neoplasia (abnormal proliferation of cells), but one that has not invaded through the basement membrane:

cis rev

There are other types of “–plasias,” such as metaplasia & desmoplasia. What do you think these terms denote and where do they come from? Let me know in the comments section!

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To expound upon my previous post regarding histology and pathology, there is an important step between conducting a biopsy and generating a diagnosis. The tissue in question must be “fixed” (preserved), sectioned (cut into slices), and stained [Origin: Old Norse steina (to paint)]. There are numerous stains and different ones are useful for different purposes. The classic stain that most students of histology are introduced to is the H&E stain. This stands for haematoxylin and eosin.

Haematoxylin
Origin: Greek, haima (blood) + xylos (wood)
Extracted from the logwood tree; depending on its preparation, its solution appears blood red

Eosin
Origin: Greek, eos (dawn)
So named after the Greek goddess of the dawn, Eos, for its red/dawny color

To start, haematoxylin is oxidized into haematein and combined with aluminum ions. This forms the active dye-metal complex, and this complex is what binds to nucleic acids to stain nuclei and ribosomes purple. (The former contains DNA in the form of chromatin and the latter is composed of RNA.) It is thought that the highly negative phosphate backbone is what binds to the positively-charged haematein. We use the word basophilic [Gk. base + philia (love)] to refer to entities that bind to basic, i.e., positively-charged dyes. I will discuss the etymology of chemical terms such as “base” in a future post!

h&e

Eosin is used as the counterstain to haematoxylin. When eosin is dissolved in water or ethanol, its carboxylic acid and phenol are deprotonated to form a negative ion. This form of eosin binds to positively-charged entities such as the positive amino acids, e.g., arginine and lysine. Hence, the cytoplasm appears red because its proteins bind to the negatively-charged eosin. We use the word eosinophilic [Gk. eosin + philia (love)] to refer to entities that bind to acidic, i.e., negatively-charged dyes.

In the 1970s, the price of haematoxylin rose steeply, and it resulted in a search for a synthetic alternative. My schoolmate and former histology TA, Dr. Alexander Morgan, relayed an interesting aside to me: “European lust for haematoxylin based dye led to British logging in South America, and why there’s one tiny, mosquito-infested, swampy country in South America where they speak English [referring to Belize]. Many people died (dyed?) of malaria trying to harvest the wood to make the stain.”

These terms present a natural tie-in to immunology. There are two leukocytes that I am referring to: one is the eosinophil, which is colored quite intensely red, and the other is the basophil, which is colored quite intensely blue. I believe a picture is in order to better illustrate:

eosinophil basophil rev2

Another interesting stain is the silver stain. Camillo Golgi, a 19th-century Italian physician and Nobel laureate, developed silver staining to study the nervous system. (The cellular organelles known as Golgi bodies are named after him.) There are two classes of cells that take up silver: the argentaffins and the argyrophiles.

Argentaffin
Origin: Latin, argentum (silver) + affinis (akin/affinity)
Affinity for silver; more specifically, cells that take up silver without a reducing agent

Argyrophile
Origin: Greek, argyros (silver) + philia (love)
Love of silver; more specifically, cells that take up silver and need a reducing agent

There are various methods for preparing different silver stains. These stains can be used for a number of applications such as:

  1. Diagnostic microbiology (staining of fungi such as Pneumocystis jiroveci)
  2. Neuropathology (staining of neuritic plaques and neurofibrillary tangles in Alzheimer disease)
  3. Histology (staining of type III collagen and reticulin)

silver stains

Left: neurofibrillary tangles of Alzheimer disease. Right: membranous nephropathy

The last stain I will briefly touch upon is the periodic acid-Schiff (PAS) stain. This stains for polysaccharides, glycoproteins, glycolipids, and the like. Hence, it can be used to diagnose things like the glycogen storage diseases, adenocarcinomas (which often secrete mucin), Whipple’s disease, etc. The reason why I bring this up is that many people say it incorrectly. It is not periodic as in “recurring time intervals.” Rather, is per-iodic, i.e., of the periodiate ion (IO4–)! Periodic acid oxidizes vicinal [L., vicinus (near)] diols to create a pair of aldehydes. These aldehydes then react with the Schiff reagent to produce a purple color.

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Here is a clinical scenario: a patient comes to your office for a routine examination. While examining the skin, you notice an ill-defined and oddly-colored brown spot on the patient’s back. Or perhaps while palpating the thyroid gland, you palpate something that doesn’t feel quite right. What is the next step in this patient’s care? If you thought to perform a biopsy, you’d be correct. Indeed, to derive insights from what a patient is suffering from, clinicians obtain a sample of tissue via biopsy from the suspect organ for the tissue to be studied histologically.

Biopsy
Origin: Greek, bios (life) + opsia (a sight)
A sight of life

Histology
Origin: Greek, histos (web/tissue) + logos
The study of tissue

This tissue can initially be examined grossly [L., grossus (thick/coarse)], i.e., by the naked eye, but clinicians often require insights from a pathologist to more completely characterize and understand the tissue they obtained. What does a pathologist study? Let’s take a look:

Pathology
Origin: Greek, pathos (suffering) + logos (word, taken to mean “study of”)
The study of suffering

This is a very generalized definition of pathology (which is absolutely wonderful to me), but let me offer my own comprehensive/digestible definition of pathology. Pathology is the molecular, histological, and gross study of disease processes and their clinical manifestations. Thus, staying true to its etymology, pathology is the systematic and scientific study of suffering. There are four main areas that pathologists explore to better understand disease: aetiology, pathogenesis, morphological changes, and clinical manifestations.

spitz papillary

Left: Spitz nevus (mole). Right: papillary thryoid carcinoma

Aetiology
Origin: Greek, aitos (cause) + logos
The study of the cause of a disease

Pathogenesis
Origin: Greek, pathos + genesis (origin/source)
The origin and development of disease

If all goes well, the pathologist will generate a diagnosis and a prognosis regarding the patient’s condition, and the clinician or the surgeon will proceed accordingly.

Diagnosis
Origin: Greek, dia– (through) + gignoskein (to know) + –osis (condition of)
A condition of knowing through, i.e., a distinguishing

Prognosis
Origin: Greek, pro- (for/before) + gignoskein + –osis
A condition of foreknowledge, i.e., the likely outcome

What tools does a pathologist use to actually study the tissue in question and generate a diagnosis? You’ll have to stay tuned to find out!

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Meningitis (plural meningitides) is a nasty condition. From the first post, we already know that meningitis is defined as the inflammation of the meninges. The meninges (singular meninx) are the protective coverings of the brain, and there are three layers, listed outermost to innermost:

  1. Dura mater (Latin, “hard mother,” since it is the thickest layer)
  2. Arachnoid mater (Neo-Latin, “spider-like mother,” since it resembles a spider web)
  3. Pia mater (Latin, “pious mother,” erroneous translation from Arabic umm raqiqah for “tender mother”)

The dura mater is also known as the pachymeninx and the arachnoid mater + pia mater are also known as the leptomeninges.

meninges

Pachymeninx
Origin: Greek, pachy (thick) + meninx (membrane)
Thick membrane, i.e., the dura mater

Leptomeninges
Origin: Greek, leptos (thin) + meninges (membranes)
The thin membranes, i.e., the arachnoid mater and the pia mater

Meningitis can be caused by bacteria, viruses, autoimmune phenomena, or trauma. If the inflammation is caused by bacteria, it is said to be (quite logically) a bacterial meningitis, but if it is caused by the latter three, it is said to be an aseptic meningitis.

Aseptic
Origin: Greek, a- (without) + sepein (to cause decay)

Though the other aetiologies “cause decay,” septic is reserved for bacteria in the medical lexicon. It is important to note that the aseptic meningitides, though wretched, do not typically cause mortality. The bacterial meningitides, however, must be identified and treated swiftly, for they have a relatively high mortality. It is for this reason that if a case of bacterial meningitis is suspected, antibiotics are indicated for immediate use, whether or not the patient truly has a bacterial meningitis. Neutrophils in the cerebrospinal fluid (CSF) is a classic diagnostic marker of bacterial meningitis:

csf pleo rev

There are numerous signs that can hint towards a patient suffering from meningitis, but two of the classic ones are nuchal rigidity (neck stiffness) and photophobia.

Nuchal
Origin: Arabic, nukah (spine)
Used in English as an adjective for the neck

Photophobia
Origin: Greek, photos (light) + phobos (fear) + -ia (condition of)
Condition of the fear of light