Track: Case Reports
Abstract:
Herein we present a case of a 54-year-old male with no significant past medical history who presented with an enlarging, fluctuant non-tender cystic mass of mucosal upper lip for 6 months duration. Histopathologic evaluation demonstrated a well-circumscribed proliferation of polyhedral basophilic epithelial cells arranged in lobular aggregates comprising solid and cystic nests, localized within the submucosal tissue contiguous to benign minor salivary gland acini. The lesional cells demonstrated strong and diffuse immunohistochemical reactivity for CK7 and p63 with staining for CEA and EMA showing prominent ductal differentiation. Although an atypical clinical presentation, these immunomorphologic features most closely aligned with a nodular hidradenoma (NH) arising in a mucosal location. NH is an adnexal tumor which arise from the distal excretory duct of the eccrine sweat gland and typically occur on scalp, face, pubic region, and axilla in the 3rd-6th decades of life with a slight female predominance. While immunohistochemical staining (e.g., EMA, CEA, cytokeratins) may be helpful, recognition of characteristic histologic features including solid and cystic architecture as well as a dual cell population and ductal differentiation, remains the gold standard. Malignant transformation is rare, though often aggressive, with reports of mortality due to disseminated disease. NH arising near a salivary gland may be diagnostically challenging, as it may mimic salivary gland tumors such as mucoepidermoid carcinoma. To our knowledge, only three cases of NH arising in mucosal sites, including the lower lip and nasal vestibule, have been reported. Our aim is to raise awareness of this rare presentation of NH.