[Focal myositis: report of a case in pediatric age and review of the literature].

INTRODUCTION AND CLINICAL CASE: We present the case of a 13 years old boy with a year-old history of a painful tumour on the external and distal third of the right thigh. The imaging tests suggested a soft tissue tumour but the muscle biopsy revealed the typical findings of focal myositis. Focal myositis is a benign inflammatory pseudotumour of the skeletal muscle recognized as a distinct clinicopathological entity, but there have been descriptions of the cases initially diagnosed as focal myositis that have latter behaved as evident polymyositis. We have not found laboratory data to support a diagnosis of polymyositis in our patient.

CONCLUSION: Although focal myositis is considered a self-limited disease, we believe a long-term clinical and biochemical follow-up is warranted, to confirm the absence of recurrence signs and/or the development of a generalized myopathy.