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Case Reports

Abstract

Microcystic/reticular schwannoma is an uncommon variant of schwannoma that histopathologically mimics an adenocarcinoma. These lesions are primarily encountered in visceral sites but rarely also found in the skin. Herein, we present two cases of cutaneous microcystic/reticular schwannoma. The first case involved a 69-year-old female presenting with a lesion on the right cheek. Histological evaluation revealed a well-demarcated, lobulated mass containing ductal-like structures filled with mucinous material, lined by cytologically bland cuboidal to spindle-shaped cells. The stroma was fibromyxoid, with scattered mast cells. Significant atypia, necrosis or mitotic activity was not identified. Immunohistochemical staining demonstrated diffuse positivity for SOX-10 and S-100 in the cells lining the microcystic/pseudoglandular spaces, while cytokeratin AE1/AE3, cytokeratin 5/6, cytokeratin 8/18, p63, CD31 and smooth muscle actin were negative. The second case was from a 71-year-old male with a perineal lesion initially clinically suspected as a fibroma. The biopsy showed distinctive microcystic and reticular, lace-like spaces lined by flat to cuboidal cells within a myxoid stroma. Additionally, this lesion also exhibited an area of conventional schwannoma. Given the rarity of microcystic/reticular schwannoma in the perineum, multiple epithelial markers were performed which were negative, while S-100 and SOX10 were positive within the lesional cells. Neither patient showed evidence of neurofibromatosis, and both remain free of recurrence.  

Microcystic/reticular schwannoma is a rare variant of schwannoma that shows ductal-like or pseudoglandular structures that may mimic metastatic carcinoma or cutaneous adnexal tumors (such as microsecretory adenocarcinoma). Our cases underscore the morphologic diversity of cutaneous benign peripheral nerve sheath tumors.