title: Low-grade adnexal carcinoma of the skin with multidirectional (glandular, trichoblastomatous, spiradenocylindromatous) differentiation.
abstract: The conjoint occurrence of follicular, sebaceous, or apocrine differentiations in a cutaneous adnexal neoplasm is a known event, more often encountered in benign neoplasms, whereas reports of cutaneous malignant adnexal tumors with bilineage or trilineage differentiation are few. A new case of a cutaneous malignant adnexal neoplasm with multidirectional differentiation is reported here. A 57-year-old woman presented with a long-standing, slowly growing, asymptomatic solitary tumor the size of a large nut in the coccygeal area, which was surgically excised. Ten years after the surgery, there was no evidence of recurrence or metastasis. Microscopically, the neoplasm was located in the dermis with focal extension into the subcutis. It was asymmetric, horizontally oriented, and mostly composed of small nodules that varied in shape from round and oval aggregations to elongated strands and irregular islands; the nodules were either clustered, formed a jigsaw puzzle-like pattern or were dispersed. The nodules were composed of small basaloid cells sometimes intermixed with larger cells with ample cytoplasm forming glandular structures. Rare nodules resembled elements seen in a spiradenoma by containing scattered lymphocytes and globules of hyalinized eosinophilic basal membrane material. The stroma was paucicellular, but focally it resembled that seen in perifollicular mesenchyme. Mitotic figures, including abnormal ones, were infrequent, but mild nuclear pleomorphism, nuclear crowding, and individual cell necrosis were easily appreciable in both small basaloid cells and cells with clear cytoplasm. Perineural invasion was apparent. We classified this tumor as a well-differentiated adnexal carcinoma demonstrating combined follicular and apocrine differentiation. It differs from previously published cases of malignant adnexal tumors with multidirectional differentiation and further exemplifies the spectrum of diversity encountered in malignant proliferations with differentiation toward the folliculosebaceous-apocrine unit.
authors.affiliation: Sikl's Department of Pathology, Charles University Medical Faculty Hospital, Pilsen, Czech Republic. kazakov@medima.cz
authors.forename: Dmitry V
authors.initials: DV
authors.lastname: Kazakov
authors.forename: Heinz
authors.initials: H
authors.lastname: Kutzner
authors.forename: Petr
authors.initials: P
authors.lastname: Mukensnabl
authors.forename: Michal
authors.initials: M
authors.lastname: Michal
mesh_terms: D000291:Adnexal Diseases / Q000378:metabolism / Q000473:pathology*; D002454:Cell Differentiation; D048430:Cell Shape; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000473:pathology; D009367:Neoplasm Staging; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology*