Fine needle aspiration cytology of pilomatrixoma

To delineate and characterize the cytomorphologic features of pilomatrixoma (PMX) helpful in correct diagnosis of the lesion on fine needle aspiration cytology (FNAC).

Archival records of clinical findings, FNAC and histopathological reports of PMX cases were analyzed. Aspirate findings in 14 cases of PMX were correlated with detailed clinical data and subsequent histopathology on excisional biopsy. Different morphological findings were graded semiquantitatively from 0 to 3+.

The series showed female preponderance, with head and neck being the commonest site. Majority patients had a single tumor with mean size of 1.6 cm. Out of 14 biopsy proven cases of PMX, cytology findings revealed PMX in 7 cases on the basis of ghost cells, groups of basaloid cells, squamous cells in combination with multinucleated giant cells and calcium deposits in a background of debris. The main reasons for erroneous diagnosis were predominance of one component over the others and non-representative aspirated material.

The cytological features of PMX are characteristic and allow a conclusive diagnosis provided the smears are examined keenly bearing in mind the diagnostic traps that can mislead a cytopathologist.