Diagnostic pitfalls of pilomatricoma on fine needle aspiration cytology

Pilomatricoma is a benign skin adnexal tumour usually seen in the head and neck region of children and young adults. It is underrecognized on cytology, resulting in the overdiagnosis of malignancy. We bring forth a case report of a slow growing nodular swelling in a 10-year-old female child, which was misdiagnosed on Fine Needle Aspiration Cytology (FNAC) as a malignant neoplasm and found to be pilomatricoma histopathologically. Nodular lesions of pilomatricoma, which are predominantly composed of basaloid cells and devoid of other diagnostic features, lead to a false diagnosis of malignancy. To avoid misdiagnosis, pilomatricoma should be considered in differential diagnosis when primitive appearing cells are aspirated in slow growing subcutaneous nodules. Cytomorphological features of pilomatricoma and major pitfalls in diagnosis are also being discussed.