Primary echinococcosis of the sternocleidomastoid muscle.

Muscular echinococcosis accounts for 0.5% to 5.4% of all hydatid disease cases, with very little data on the incidence of muscular echinococcosis of the head and neck. We report a unique case of primary echinococcosis of the right sternocleidomastoid muscle in a 56-year-old man. Preoperative assessment by ultrasound and fine needle aspiration did not point to echinococcosis. We suspected the right diagnosis intraoperatively and confirmed it postoperatively by pathohistology and serologic tests. Echinococcosis of the liver and the lungs was also excluded postoperatively. Combination of operative treatment and postoperative albendazole herapy in two 28-day cycles one month apart resulted in complete regression of the disease. Echinococcosis should be considered as differential diagnosis of a multicystic mass in neck, particularly if it is of longstanding duration. Serologic tests for echinococcosis should be included in differential diagnostic procedures for each multicystic formation on the neck, especially in endemic areas.