Derm101 Case: Basal Cell Carcinoma, Nodular

Exposition

Criteria for diagnosis clinically: A pink papule with a hint of a violaceous cast, whose mostly shiny, smooth surface is traversed by telangiectases and whose border is scalloped subtly, represents a nodular type of basal-cell carcinoma.

Differential diagnosis clinically: There is none.

Criteria for diagnosis histopathologically: An asymmetrical neoplasm made up of abnormal trichoblasts organized in aggregations, some of which are separated by clefts from the adjacent altered stroma and are affiliated with necrosis of individual neoplastic cells joined by large zones in the center of aggregations that contain mucin in quantity, are findings that compute to a diagnosis of basal-cell carcinoma of the nodular type.

Differential diagnosis histopathologically: There is none.

Clinicopathologic correlation: The papule consists largely of aggregations of neoplastic cells; the reddish hue and the telangiectases are the result of capillaries and venules in the uppermost part of the dermis having been dilated widely in vivo and there stuffed with erythrocytes; and the shiny, smooth part of the surface is accounted for by compact orthokeratosis, whereas the scaly part is a manifestation of parakeratosis.

Options for therapy predicated on knowledge of histopathologic findings: A carcinoma such as this one must be removed in its entirety and although the neoplasm does extend to near one lateral margin, it seems, nonetheless, to have been extirpated. That being the case, it is still important to follow this patient at six-month intervals for one year to ensure that the basal-cell carcinoma does not persist at the local site.

Lessons

(1) The neoplasm shown here fulfills criteria, clinical and histopathologic, for diagnosis of nodular basal-cell carcinoma. Note how thin is the surface epidermis, an indication that likely it will not be long before evidences of erosion and, eventually, ulceration, became apparent.

(2) Signs of necrosis of individual neoplastic trichoblasts here are pyknosis and karyorrhexis. The cystic zones do not, however, consist of a mass of necrotic neoplastic cells, but rather of mucin, which appears as finely granular, lightly basophilic material. Neoplastic cells of basal-cell carcinoma have potential to manufacture acid mucopolysaccharides, and that capability is demonstrated well in this neoplasm.

(3) All epithelial cells in skin have capability to produce mucin. In normal skin that property is expected of apocrine glandular epithelium. In states pathologic, such as epithelial ("follicular") mucinosis, mucin is made by infundibular epithelium, sebaceous glandular epithelium, and follicular epithelium. Fibrocytes, possibly in conjunction with mast cells, also have capability to manufacture mucin, it being present normally in the papillary-periadnexal dermis and, to a much lesser extent, in the reticular dermis. Copious amounts of mucin appear in focal mucinosis, myxedema, and pretibial myxedema, in much less quantity in lichen myxedematosis, and somewhere in between in lupus erythematosus and dermatomyositis. The character chemically of "connective tissue mucin" is different from that of "epithelial mucin."

(4) Both benign and malignant epithelial neoplasms in skin may be associated with production of mucin. A dramatic example of that in a benign neoplasm is "eccrine mixed tumor" in which tiny donut-shaped aggregations of eccrine epithelial cells are embedded in lakes of mucin. Sometimes an apocrine hidradenoma is peppered by goblet cells whose cytoplasm houses plentiful mucin. Carcinomas of different types, in addition to basal-cell carcinoma, also may be affiliated with mucin, among those being keratoacanthomatous squamous-cell carcinoma and, in caricature, mucinous carcinoma (it being the analogue of colloid carcinoma of the breast and showing apocrine glandular differentiation). In theory, constituent neoplastic cells of any carcinoma of the skin have capability to make mucin.

(5) Both necrosis of neoplastic cells and production of mucin can occur together in basal-cell carcinoma, as is the situation here, or they can occur independent of one another.

(Source: Derm101)