A case of pseudophlebitis of the v. saphena magna: focal nodular myositis of m. gracilis

A case of focal myositis in a healthy 68-year-old woman is described. The p atient was admitted for evaluation of a painful soft-tissue mass localised on the medial side of the left thigh, initially misdiagnosed as thrombophle bitis of the v. saphena magna. Laboratory data were normal, in particular s edimentation rate and muscle enzyme levels. After exclusion of venous throm bosis, the mass localised in the left m. gracilis was surgically removed. H istologic examination of the biopsy specimen showed muscle cell necrosis an d severe inflammation, with lymphocytic infiltration leading to the diagnos is of focal myositis. This is a rare benign inflammatory pseudotumour of sk eletal muscle. The aetiology and pathogenesis of the disease remain unclear . It is most commonly seen in the lower extremities and may mimic thromboph lebitis or soft-tissue neoplasm. Ultrasound and magnetic-resonance scans ar e helpful, but definitive diagnosis is obtained only by histology. Because recurrent lesions in other skeletal muscles are possible, and a third of pa tients develop polymyositis, a follow-up of several years is recommended.