Dermatopathology: An abridged compendium of words. A discussion of them and opinions about them. Part 4

DARK CELLS: of eccrine glands are secretory and characterized ultrastructurally by numerous vacuoles that contain mucin. The name “dark” comes from the electron-dense appearance of the cells in contrast to the electron-lucid character of light cells of eccrine glands. The terms dark cell and light cells (also known as clear and pale cells) are used also to contrast two populations of cells within a particular neoplasm, i.e., spiradenoma, wrongly designated “eccrine spiradenoma” because differentiation of that neoplasm is apocrine. In most instances, a dark appearance results from scant cytoplasm, which causes nuclei to appear crowded, as much as from dense nuclear chromatin. Light cells have abundant glycogen in their cytoplasm. At scanning magnification lymphocytes appear dark in color even “black.” This is helpful in diagnosis.

The neck of a bud becomes progressively thinner and eventually is lost into the lumen, giving the impression of having been "pinched off' or decapitated. In the realm of hamartomas and neoplasms, the finding of definitive "decapitation secretion" is specific for apocrine differentiation. The terms apocrine secretion, "decapitation" secretion, "pinching-off' secretion, and snouts are synonyms. DEGENERATON: in classic pathology, particular alterations detectable microscopically either in cells or in extracellular tissue, i.e., hydropic degeneration of cells and degeneration of collagen. The term is applied incorrectly to "liquefaction degeneration" of the basal layer, those changes consisting only of vacuoles situated immediately above and below the basement membrane, and to "mucinous degeneration" of a neural neoplasm where "degeneration" is employed as a synonym for deposits of mucin. "Fatty degeneration" of neutrophils has been reputed to be responsible for the yellow color of pus, a claim that probably is without merit. Elastotic material that results from longstanding injury to skin by the effects of ultraviolet light is not a degeneration of collagen, as it is purported to be, but rather a faulty product of fibrocytes.
Degeneration of cells designates injury that may not necessarily be fatal; that is, the cells are not yet dead and, therefore, are able to recover fully, as in examples of ballooning degeneration early in its course, i.e., before spinous cells have swollen dramatically and before reticular alteration has come into being. Once, however, either of those two latter changes has eventuated as a consequence of ballooning severely, necrosis of keratocytes is inevitable and invariable.  Bundles of collagen and fibers of elastic tissue are more delicate in the papillary dermis than they are in the reticular dermis. The papillary dermis also is more richly vascularized by capillaries and contains more mucin than does the reticular dermis. A dermal papilla should not be confused with a follicular papilla, to wit, the spade-shaped, mucin rich, capillary-invested connective tissue structure that invaginates the bulb of a follicle in full-fledged anagen and has different appearances at other phases of the follicular cycle.
DERMATITIS: inflammatory disease in which the infiltrate of inflammatory cells is present in the dermis, a definition that is applied scrupulously throughout this work, in contrast to the way the term "dermatitis" is used in virtually every text of dermatology and dermatopathology, namely, as a synonym for "eczema," a term that we employ only for purposes of decrying it.

DERMATOSCOPY (not dermoscopy)
: is a special procedure that may help define whether a skin lesion is benign or malignant clinically. It has other related uses. The procedure uses a dermatoscope There are no "true" words "dermoscopy" and "dermoscope;" the words correct are "dermatoscopy" and "dermatoscopic." And that is precisely why disciplines are named dermatology, not dermology, and dermatopathology, not dermopathology. i.e., dermatitis. Confusingly, some authors use "dermatosis," in contradistinction to "dermatitis," for skin conditions that are not characterized by inflammation clinically. In our judgment, the term "dermatitis" or "inflammatory disease of the skin" is preferable to "inflammatory dermatosis" because it is more direct, "dermatosis" being generic, not specific, and employed for diseases other than inflammatory ones. In the past four decades, general pathologists have perverted the definition original of dysplasia and in its place have introduced a bevy of new definitions for it, those being as disparate as "cytologic atypia," "atypical hyperplasia," "abnormal growth," "aberrant differentiation," and "architectural and cytologic atypia." Because no single definition, intelligible and repeatable, exists for dysplasia, use of that term serves only to impede communication between and among pathologists, to say nothing of discourse rational between pathologists and clinicians. For that reason, the term "dysplasia" should be avoided scrupulously.

DYSPLASTIC NEVUS:
As it is "pictured" it is the most common of all nevi, it being characterized clinically by variability in size (from a few millimeters to more than a centimeter) and in hue, it usually being tan and flat at the periphery and darker brown and only slightly elevated in the center, but sometimes displaying more than two shades of brown.
When compound, it is typified histopathologically by having the silhouette of a benign neoplasm (i.e., symmetrical, well circumscribed, etc.), being only slightly elevated, if at all, and displaying small nests of melanocytes at the dermoepidermal junction and, in the very center of the lesion, a few nests small in the papillary dermis, the nuclei of those melanocytes being small, oval, and monomorphic. The concept of dysplastic nevus is predicated on the notion of melanocytic dysplasia, a term that has yet to be defined in a crisp, comprehensible, repeatable way. We eschew the term "dysplasia" and "dysplastic nevus," the former because it is unnecessary in general and for diagnosis with specificity in particular, and the latter because we name nevi eponymically, in the case of so called dysplastic nevus for Clark, of so-called juvenile melanoma for Spitz, and of so-called pigmented spindle-cell tumor for Reed. Last, dysplastic nevi were said, over and over again, by Clark and acolytes to be a "precursor" of melanoma and a "marker" for persons at risk for melanoma. They are neither.
Less than 10% of all melanomas in the world, i.e., in persons of all races, develop in association with a preexisting nevus of any kind, and then the most common nevus, by far, is a congenital one that affects markedly the thickened papillary dermis (superficial) or the upper part of the reticular dermis (superficial and "deep"), not an acquired "dysplastic" one.
Moreover, no relationship has been proven between the presence of so-called dysplastic nevi and risk for developing melanoma. It is true that episodically a melanoma may develop in continuity with a Clark's nevus, just as it may in association with any kind of melanocytic nevus.
DYSPLASTIC NEVUS SYNDROME: a misconception based on misperceptions, namely, of "melanocytic dysplasia" and "dysplastic nevus." The so-called syndrome consists of a single element, to wit, dysplastic nevi, and, therefore, does not fulfill criteria for a syndrome, which is a constellation of signs and symptoms that constitute a disorder. Furthermore, no agreement exists about how many of those nevi are requisite for diagnosis of the "syndrome," some authors insisting that "only a single nevus" is sufficient, whereas others contend that more than 100 of them are necessary. ENDOPHYTIC: growing inward, as from the surface of the skin, like a morpheaform basal-cell carcinoma.
EPIDERMAL HYPERPLASIA: an increased number of cells, especially spinous ones, in a thickened epidermis. We employ it as a synonym for acanthosis because the latter is a parochial term restricted in scope to cutaneous pathology. Because dermatopathology and general pathology are one pathology, one language should be used for both. Strictly speaking epidermal hyperplasia applies also to an increased number of cells in the cornified layer, but by convention that abnormality is termed hyperkeratosis. So, too, epidermal hyperplasia includes an increased number of granular cells, but, by custom, that phenomenon is designated hypergranulosis. For the aforementioned reasons, we use epidermal hyperplasia as a synonym for spinous cell hyperplasia of the epidermis.
EPIDERMAL NEVUS: hamartoma characterized by papillated or digitated proliferation of epidermal keratocytes and associated almost always with hyperkeratosis.
EPIDERMOLYTIC HYPERKERATOSIS: refers to a pattern within an epithelium, especially epidermis, characterized by enlarged, markedly vacuolated keratocytes with feathery borders, within whose cytoplasm are numerous coarse keratohyaline granules and on occasion, trichohyalin granules.
The boundaries between the keratocytes appear to be lysed.

Visualization of the cells by electron microscopy reveals that
there actually is no lysis: the cells are cohesive. All of these changes occur in association with marked orthokeratosis. The word epidermotropic is not defined in any of the main medical dictionaries, nor is it in textbooks of dermatology or dermatopathology. As for epidermotropism, it is only defined in a minority of dictionaries and in some textbooks.

EPIDERMOPOIESIS
Strictly speaking, the suffix tropism implies a movement; the best example is the turning or bending phenomenon plants undergo in response to light as the environmental stimulus.
This response is called phototropism. Literally, epidermotropism means a "turning towards the epidermis or having an affinity for the epidermis." When checking the words "epidermotropism" and "epidermotropic" in dictionaries, textbooks, and journals, it is hard to find them unassociated with mycosis fungoides. In the rest of the cases, those words are used almost exclusively for other lymphomas, especially the T-cell lymphomas. It is difficult to find other diseases with "epidermotropic" alterations, but when that happens, interestingly they are almost always malignant processes, i.e., carcinomas such as Paget's disease or porocarcinomas, or metastatic melanomas. Last, there are only isolated usages of the words "epidermotropism" or "epidermotropic" in inflammatory conditions in part because, as it can be inferred from literature, those words are apparently synonymous with malignancy.
In addition, epidermotropism and epidermotropic seem to imply the diagnosis of mycosis fungoides, and vice versa.
Equally and for the same reason, epidermotropism is linked to an infiltrate of lymphocytes, and it is not used when the infiltrate is made of other cells.
What dermatopathologists call "epidermotropism" most of the time is the presence of lymphocytes in the epidermis.
However, in more than half of the routine cases in a dermatopathology laboratory, there are lymphocytes within the epidermis, as in any spongiotic psoriasiform, or interface dermatitis, even in epidermal or melanocytic "tumors", and none of these infiltrates are usually referred to as epidermo-  EXOPHYTIC: growing outward, as from the skin surface, like a filiform verruca.