Pilomatrixoma as a diagnostic pitfall in fine needle aspiration cytology - A case report

Background Pilomatrixoma (pilomatrixoma, calcifying epithelioma of Malherbe) is a relatively uncommon, benign neoplasm arising from the skin adnexa. The tumor can cause diagnostic difficulty not only for the clinician but also for the cytologist. Case A 62-year-old woman presented with a right suhmandibular swelling of 4 months' duration. The clinical findings were highly suspicious for malignancy. A fine needle aspiration biopsy was performed. Three preliminary differential diagnoses were offered: mucoepidermoid carcinoma of the submandibular salivary gland, squamous cell carcinomatous deposit in a suhmandibular lymph node and calcifying odontogenic tumor. Computed tomography demonstrated no bony lesion. No primary site of squamous cell carcinoma could be identified. An excisional biopsy of the swelling was performed, and the histologic diagnosis of pilomatrixoma was made. Conclusion The cytologic presentation of pilomatrixoma of the right submandibular region can masquerade as that of a malignant tumor, in this case mucoepidermoid carcinoma, squamous cell carcinoma or odontogenic tumor. This case delineates the cytomorphologic features of pilomatrixoma that may mimic carcinoma.