Primary CD30/ALK-1 positive anaplastic large cell lymphoma of the skeletal muscle in a child.

Anaplastic large cell lymphoma (ALCL) represents approximately 10 to 30% of all childhood non-Hodgkin lymphomas. It frequently involves both lymph nodes and extranodal sites whereas primary or secondary muscular involvements are quite uncommon. We describe a case of an 8-year-old boy presented with one month progressively swelling right buttock mass without association of lymphadenopathy or skin extension. Biopsy of the lesion showed large anaplastic cells with voluminous and abundant cytoplasm as well as folded nuclei. The tumour cells were positive for CD30, CD3, EMA and ALK-1. Chemotherapy resulted in durable remission status. This case emphasizes the occurrence of anaplastic large cell lymphoma in the soft tissue and the favourable outcome of ALK-positive anaplastic large cell lymphoma.