[Sea urchin sting synovitis. Report of 4 cases].

Accidental sea urchin stings do not usually have any pathological consequences. However, cutaneous, synovial or toxic diseases can develop in some predisposed subjects, or under predisposing circumstances. The diagnosis, sometimes very delayed, can be difficult. Four personal cases of reactive arthritis or tenosynovitis, three of which affected the hand, are reported. All patients were cured after one or several surgical excisions. Antibiotics were not effective. The main clinical presentations, particularly delayed synovitis, are described. The various pathogenic hypotheses are in favour of an immunological reaction to the envelope protein of the sea urchin spikes.