High (Nuclear) Grade Adnexal Carcinoma With Microcystic Adnexal Carcinoma-Like Structural Features

Abstract

Microcystic adnexal carcinoma (MAC) is a slow growing, locally aggressive sweat gland tumor. It predominantly affects the face and tends to recur despite local excision. Microscopically, MAC is characterized by a stratified proliferation of microcysts, cords, and ducts of cells that show squamous or adnexal differentiation. Atypia and mitoses are almost completely absent and metastatic deposits are rare and mostly limited to the regional lymph nodes; rather than real metastases, they might be the result of local extension of the tumor through perineurial spaces. We report a case of adnexal carcinoma with architectural features of MAC that displayed also marked nuclear pleomorphism and hyperchromasia with squamous pearl formation and a widespread strong p53 immunoreaction. The lesion behaved as a high-grade neoplasm with rapid growth, carcinosarcomatous metaplastic transformation in a relapse, and what were clinically suspected to be metastases. The literature contains several other examples reported as metastatic high-grade MAC, one of them with widespread distant metastases. We therefore want to sound an alert about the possible existence of tumors displaying microscopic findings characteristic of the aggressive forms of sweat gland carcinoma (nuclear pleomorphism and hyperchromasia, vascular invasion, and necrosis) in addition to architectural features of MAC. Whether these tumors should be called high-grade MACs or belong to a separate category remains an open issue until more cases are reported and bridge cases are eventually documented.

Solid carcinoma is a variant of microcystic adnexal carcinoma: A 14‐case series

“…Regarding immunohistochemical results, a high regulation of p53 is associated with uncontrolled proliferation, and immunohistochemical detection of a higher percentage of positive p53 cells is interpreted as an indicator of aggressive behavior . Positive staining for p63 in up to 95% of nuclei has been described in a tumor resembling MAC but with an important nuclear pleomorphism, and Smith et al studied p53 in 10 cases of classic MAC, finding only two cases with more than 25% of tumoral nuclei positive for p53 . A correlation between p53 overexpression and short survival has been reported in sebaceous gland carcinoma, and p53 may be a useful marker not only to segregate aggressive variants where we usually find nuclear pleomorphism, hyperchromatic nuclei, mitotic figures, necrosis, and intravascular invasion, but also to distinguish tumors where regional lymph node dissection and radiation may be useful .…”

Sclerosing ductal carcinoma of the clitoris with microcystic adnexal carcinoma‐like features

“…However, after extensive review, she likely has a sclerosing ductal carcinoma with features similar to MAC 13 . Published reports suggest syringomas, and high‐grade adnexal carcinomas have MAC‐like features and are often misdiagnosed as MAC 13–15 . Suwattee et al limit the differential diagnosis between plaque‐type syringomas and MAC by a clinical history of multiple superficial plaques, a lack of concomitant superficial follicular differentiation and an absence of perineural extension 13 …”

“…13 Published reports suggest syringomas, and high-grade adnexal carcinomas have MAC-like features and are often misdiagnosed as MAC. [13][14][15] Suwattee et al limit the differential diagnosis between plaque-type syringomas and MAC by a clinical Fig. 1.…”

Microcystic Adnexal Carcinoma

“…Mitoses, necrosis, and cellular atypia are by and large absent but have been reported to occur. 9 Immunohistochemistry is not a key method used in diagnosing MAC and is only somewhat helpful in delineating similar histopathologic entities. The most common immunohistochemical stains employed are carcinoembryonic antigen (CEA), epithelial membrane antigen (EMA), cytokeratin 7, and S-100, all of which stain epithelial cords, nests, and ductal structures.…”