Diffuse pigmented villonodular synovitis in the metatarsophalangeal joint of the hallux: a case report

A 60-year-old woman presented to our institution with a 2-month history of swelling and unrelieved pain on walking, localized to the right hallux. Magnetic resonance image scans revealed a multinodular soft tissue mass with low signal intensity on both T1- and T2-weighted images. Microscopic examination of a specimen procured using fine-needle biopsy revealed multinucleated giant cells, hemosiderin deposition, and foaming histiocytes, indicative of pigmented villonodular synovitis. Thereafter, excision of the mass and a thorough synovectomy were carried out using 2 separate longitudinal incisions. Although pigmented villonodular synovitis of the first metatarsophalangeal joint is not unheard of, it is relatively rare and physicians should consider it in the differential diagnosis when treating patients with prolonged chronic arthritis of the first pedal ray. This case, moreover, clearly depicts the diagnostic value of magnetic resonance imaging combined with fine-needle biopsy in regard to making the diagnosis of pigmented villonodular synovitis.

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