Latent foreign body synovitis.

The differential diagnosis for monoarticular arthritis is extensive. Patient omissions from the history can compound this broad diagnostic dilemma. A case report is presented of a 32-year-old female with an eight-month history of isolated right first metatarsophalangeal joint (MTPJ) pain, after exhaustive, non-specific diagnostic evaluation. An open biopsy was performed, and a 3.5 cm wooden foreign body, believed to be the result of an injury 18 years prior, was excised from the 1st MTP. Open biopsy may be required as an important part of the workup for definitive diagnosis of a foreign body synovitis. A discussion regarding the presentation, clinical and diagnostic findings follows.