Diagnostic pitfalls in fine needle aspiration cytology of pleomorphic lipoma. A case report.

BACKGROUND: Pleomorphic lipoma is an unusual pseudosarcomatous condition with characteristic morphology. Despite its pleomorphic appearance, it follows a benign course and does not recur or metastasize if completely excised. CASE: A 66-year-old man presented with swelling in the back of the neck of approximately six months' duration. The focally cellular aspirate revealed round to oval, hyperchromatic cells, rare multinucleated cells and fragments of mature adipose tissue. On initial evaluation, the smear pattern suggested a malignant neoplasm. However, upon review of the cytologic material along with histology, the characteristic pattern, including floret cells, was recognized. CONCLUSION: The rarity of pleomorphic lipoma and the atypical cellular features of the aspirate can cause difficulty in diagnosing this entity. Awareness of this rare but not-uncommon entity, along with clinical correlation, is crucial in arriving at the correct diagnosis.