Fibroma of the tendon sheath: A diagnostic dilemma on fine-needle aspiration cytology.

Fibroma of the tendon sheath (FTS) is an uncommon benign soft tissue tumor (STS) of the tendon sheath. Clinical and radiological features are not distinctive enough to clinch the diagnosis preoperatively. Although histological features are well described, diagnostic cytological features of FTS are still lacking. Till date only two reports describe the fine-needle aspiration cytology (FNAC) findings of FTS. The present case is a 50-year-old female who presented with a slow growing nodule on the right thigh over a period of 2 years. FNAC revealed low cell yield with loose clusters of fibrotic spindle cells and stellate cells intermingled with fibro-collagenous and myxoid matrix. Few cells showed mild degree of nuclear atypia. Necrosis and atypical mitoses were not seen. Cytology findings were suggestive of benign/low-grade fibroblastic or fibromyxoid lesion. Histology confirmed the diagnosis of FTS. This article discusses the diagnostic role of FNAC in FTS with its differential diagnosis.