Case Report: Cytodiagnosis of pigmented villonodular synovitis involving carpal bones of right wrist

Background: Pigmented Villonodular Synovitis (PVNS) is a rare disease of osteoskeletal tissue. Cytodiagnosis of PVNS on fine needle aspiration (FNA) smears is therefore rarely reported. The PVNS usually affects the larger joints. The involvement of the smaller joints and bones are uncommon.

Case presentation: The reported case is one such rarity wherein the diagnosis of PVNS was carried out on the FNAC. The case showed the involvement of all carpal bones except for the pisiform. The 2 ^nd- 5 ^th metacarpal bases were also found to be involved in the disease process. The presence of sheets of synoviocytes with brown altered hue to the cytoplasm along with multinucleate giant cells and pigmented macrophages were characteristically present in the smears of FNA. The diagnosis was confirmed on the tissue biopsy. The present case is reported for its unusual multiosteotic involvement of wrist joint bones and the metacarpal bones simultaneously with radiological evidence. The cytomorphology of the lesion in the present case were noteworthy as a learning experience in reporting of PVNS of wrist joint on FNA smears.