Quiz 55: What is your diagnosis?

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Diagnosis: Quiz 55

Quiz 55

Answer:  Basal-cell carcinoma, nodular

Criteria for diagnosis clinically: A shiny, opalescent, tan papule, whose smooth surface is traversed by telangiectases, represents a nodular type of basal-cell carcinoma.

Differential diagnosis clinically: There is none.

Criteria for diagnosis histopathologically: An asymmetrical neoplasm punctuated at one side of it by an infundibular cyst and made up of aggregations, variable markedly in size and shape, of abnormal follicular germinative cells (trichoblasts), those aggregations being separated from the scant stroma by encircling clefts, is a basal-cell carcinoma of the nodular type.

Differential diagnosis histopathologically: There is none.

Clinicopathologic correlation: The papule is formed of aggregations of neoplastic cells, the smooth but shiny surface is a result of a rather thin cornified layer that consists of corneocytes arranged compactly, and the telangiectases are a reflection of extraordinarily dilated capillaries and venules in the upper part of the dermis, they, in vivo,having been stuffed with erythrocytes.

Options for therapy predicated on knowledge of histopathologic findings: The carcinoma must be removed in its entirety with a narrow margin, that having been accomplished in this instance as can be told by a glance at scanning power magnification.

1) Clinically the lesion is stereotypical of nodular basal-cell carcinoma. The term nodular as it is employed here refers to the size and character of the solid aggregations of neoplastic cells as they are viewed by microscopy conventional, not to the size of the lesion itself as assessed by "naked eye" examination, it being a papule, not a nodule.

2) Histopathologically, the changes are characteristic of basal-cell carcinoma of the nodular type. The cells that make up the aggregations are neoplastic analogues of those cells in germs positioned at the base of surface ectoderm in a 10-week-old embryo, they giving rise rather rapidly to the entire infundibulo-apocrine-sebaceous-follicular unit. In short, the constituent cells are abnormal trichoblasts and, that being so, a basal-cell carcinoma really is a trichoblastic carcinoma.

3) The abnormal trichoblasts of basal-cell carcinoma, by virtue of their relationship to a particular germ in an embryo, have capability to differentiate along four lines:

  • infundibular epidermis
  • apocrine gland and duct
  • sebaceous gland and duct
  • hair follicle

That potential is exercised often in regard to follicular differentiation, a basal-cell carcinoma often exhibiting elements that resemble closely a follicular germ (as it appears at the very onset of anagen at the base of the isthmus of a follicle in both a child and an adult), the crowded nuclei of columnar cells at the periphery of it being arrayed in a palisade. Sometimes the abnormal trichoblasts of basal-cell carcinoma mature to become matrical cells that then differentiate to become cells that contain trichohyalin granules and that eventuate in blue-gray corneocytes of the inner sheath. Rarely, even "shadow cells"(attempts faulty at formation of hair shaft) can be spotted in a basal-cell carcinoma, they also being a product of differentiation of matrical cells.

4) Extremely uncommon it is for there to be any sign in a basal-cell carcinoma of either sebaceous or apocrine differentiation, but both can and do occur. Not uncommonly, tiny structures that resemble an infundibular (epidermal) cyst appear in the center of nodules of basal-cell carcinoma. In this instance, however, a true infundibular cyst is present coincidentally in association with the basal-cell carcinoma, the lining of it being just like that of infundibular epidermis.

5) Note how few neoplastic cells are necrotic in this particular basal-cell carcinoma. Only an occasional pyknotic nucleus and paltry karyorrhexis can be spied near the center of some aggregations. There is no evidence at all of necrosis  en masse.  When extensive necrosis en masse in the center of aggregations of basal-cell carcinoma is lost during processing of the tissue and leaves behind a large space, the neoplasm is referred to as "cystic basal-cell carcinoma."

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