Pilomatricoma Called “Tumor Perplex”-Perplexity Continues with this Large Pilomatricoma-Still a Diagnostic Pitfall

Pilomatricoma/calcifying epithelioma of Malherbe/Tumor perplex represents a rare benign skin tumor. Accuracy of pre operative diagnosis ranges from 0–30% ⁹ and these cases are frequently misdiagnosed on fine needle aspiration cytology (FNAC). In this paper we present a case of unusually large pilomatricoma at a rare site in an adult male which was misdiagnosed as round cell neoplasm on cytology smears. Even though it has a unique morphological appearance in tissue sections it is often misdiagnosed on cytology smears.

This report is to emphasize the major pitfalls, differential diagnosis and cytomorphological and histopathological features of pilomatricoma and to highlight the importance of keeping this clinical diagnosis in mind for nodular lesions of the head and neck (>50%), upper extremity, trunk and lower extremity in decreasing order of frequency and shows female predominance^.10

Most studies have reported cases of lesions measuring 0.5 to 3 cm diameter.^{8, 10, 11} This case presented with unusually large size of 5x4x1.5 cm which has not been reported to the best of my knowledge.