Apocrine cystadenoma: A long-standing apocrine hidrocystoma with an adenomatous proliferation.

BACKGROUND: Apocrine cystadenoma is a rare, benign adenomatous cystic neoplasm, the pathogenesis of which is not fully understood. We sought to characterize the clinical, dermatoscopic, and histopathologic features of apocrine cystadenoma and its relationship to hidrocystoma. METHODS: We retrospectively analyzed cases of apocrine cystadenoma and hidrocystoma retrieved from the dermatopathology laboratory information system. RESULTS: Of the 350 cases apocrine cystic lesions, 13 cases of apocrine cystadenomas met the inclusion criteria. The age ranged from 20 to 84 years with an average of 64 years. They were long-standing (duration 3-15 years), slow-growing, large tumors usually found on the scalp. Dermatoscopy accentuated translucent light to dark blue color and prominent vessels that were present more at the periphery. All lesions were multilocular with columnar to cuboidal lining and decapitation secretion. A large portion of the lesion consisted of a simple nonproliferative epithelial lining, identical to that observed in apocrine hidrocystomas, while the proliferative adenomatous component made up a smaller portion with two patterns: (1) tubular proliferation, which either protruded into the cystic cavity or expanded outward peripherally, or (2) papillary projections, which were multiple layers thick with fibrovascular core, sometimes accompanied by tubular proliferation. Immunohistochemical stains showed strong staining for p40 and a sparse number of cells stained for Ki-67 and p53. CONCLUSIONS: The long duration of the lesion and the large areas of simple apocrine epithelial lining suggest that apocrine cystadenomas arise from long-standing apocrine hidrocystomas. However, the retrospective nature of the study from a single institution is a limitation.

Hypergranulotic Dyskeratotic Acanthoma: Another Histologically Distinctive Acanthoma.

ABSTRACT: Various acanthomas have been named based on their distinctive histopathologic patterns. Hypergranulotic dyskeratotic acanthoma represents another acanthoma with a distinctive histopathologic pattern that has been rarely reported. In this article, clinical and histological features of hypergranulotic dyskeratotic acanthoma are delineated. A retrospective analysis was performed of cases with diagnosis or suggested diagnosis of hypergranulotic dyskeratotic acanthoma between 2012 and 2017 from 2 dermatopathology laboratories. Forty-eight potentials were identified, of which 18 cases met the inclusion histologic criteria. Most cases came from women (78%) with a mean age of 53 years, and the thigh was the most common site involved. All cases had the following histopathological findings: (1) verrucous or digitated epidermal hyperplasia, (2) hyperkeratosis dominated by basketweave or compact orthokeratosis, (3) hypergranulosis involving the breadth of the lesion, and (4) presence of enlarged, often indistinctly bordered, keratinocytes with cytoplasm characterized by a blue-gray granular peripheral zone sometimes showing outstretched desmosomes and central perinuclear eosinophilic zones, a combination of findings representing slowly evolving dyskeratosis. Retrospective nature and a small sample size are the major limitations of the study. In sum, hypergranulotic dyskeratotic acanthoma can be easily distinguished from other acanthomas based on their repeatable histopathological findings.