Fine-needle aspiration cytology of pilomatrixoma: A short series of three cases

Pilomatrixoma (PMX) (pilomatricoma, calcifying epithelioma of Malherbe) is a benign tumor with differentiation toward the hair matrix cells and is common in head and neck region. It is most commonly seen in the first two decades of life and presents as a subcutaneous, small, asymptomatic firm solitary nodule. Fine-needle aspiration cytology (FNAC) has been described as an important preoperative diagnostic investigation though on cytology the diagnosis of PMX is sometimes difficult and misdiagnosed. We describe two patients with gradually increasing asymptomatic swelling on pinna and middle finger. FNAC was done and a diagnosis of PMX was given, further confirmed by histopathological examination. The present cases highlight the importance of FNAC in considering PMX as differential diagnosis of dermal or subcutaneous nodules in locations other than head and neck. Cytopathologists who play an important role in the preliminary diagnosis should keep in mind the variability of the cellular composition of these types of lesions to avoid misdiagnosis.