[Thorn synovitis: Report of 2 cases]

Thorn synovitis is related to plant or animal thorn punctures. We report two cases of thorn synovitis.

The first patient was a 41-year-old-woman who presented with recurrent arthritis of the right knee after needle fish injury. The immunological tests and cultures were negative. X-rays and MRI showed the foreign bodies in the soft parts on the outer side of the knee. An arthroscopy was performed and the thorn removed. Clinical outcome was favourable with complete symptoms resolution. The second patient was a 58-year-old-man, with a family history of spondylarthritis, who was admitted with a monoarthritis of the left wrist that occurred 10 weeks after palm tree thorn injury. Patient received unsuccessfully antibiotics and anti-inflammatory drugs. Immunological tests and cultures were negative. Wrist ultrasound showed erosive synovitis. Intra-articular lesion removal by arthroscopy allowed favourable outcome.

Thorn synovitis diagnosis is based on the discovery of a foreign body. Treatment is based on their removal. Suspicion of infection with deficient pathogen, especially Pantoea agglomerans, remains difficult for the practitioner.