Parotid basal cell adenoma with atypia: Navigating the diagnostic gray zone, case report and a brief review of the literature

Basal cell adenoma (BCA) is an uncommon benign salivary gland neoplasm that most often arises in the parotid gland and is usually managed successfully by complete surgical excision. Its diagnostic importance lies in its morphologic overlap with malignant basaloid tumors, particularly basal cell adenocarcinoma and adenoid cystic carcinoma, in which invasion and perineural spread carry major prognostic and therapeutic implications.

We present a 58-year-old female with a slowly enlarging, painless right preauricular mass and no facial nerve dysfunction. Imaging demonstrated a sharply circumscribed superficial parotid lesion, and fine needle aspiration favored a benign basaloid neoplasm. She underwent right superficial parotidectomy with facial nerve preservation. Permanent sections showed a well-circumscribed, partially encapsulated solid and trabecular basaloid tumor with focal peripheral cribriform architecture. The tumor showed rare mitoses, clear margins, preserved myoepithelial differentiation, and no unequivocal perineural, lymphovascular, or infiltrative growth. The Ki-67 index was approximately 8%, supporting a benign process despite architectural atypia. After multidisciplinary review, the final diagnosis was BCA with atypia.

This case illustrates the diagnostic gray zone created by focal cribriform change and reinforces the notion that invasion, rather than architecture alone, remains the decisive criterion guiding conservative postoperative management.