Childhood anaplastic large cell lymphoma Ki-1/CD30: clinicopathologic features of 19 cases

The authors report their cumulative experience of 19 children with what was previously called malignant histiocytosis (MH) but is now considered a true lymphoma and termed anaplastic large cell lymphoma (ALCL). The median age at diagnosis was 10 years and 6 months (range 2 y, 11 m, to 15 y). There were 13 males and 6 females. Most cases presented with fever, wasting and enlarged, often tender, lymph nodes. Other features were: fleeting cutaneous rashes in 7 cases; spontaneous regression of lymph nodes and skin lesions were seen in 5 patients. Bone marrow involvement was present in 3 cases, pulmonary infiltrate in 5, kidneys in 2, and central nervous system in none. The morphology of lymph node involvement was consistent with so-called MH, a description originally applied to sinusoïdal infiltration by large "histiocytic" cells. The coexpression of lymphoid activation antigens Ki-1/CD 30 (18/19), epithelial membrane antigen EMA (18/19) and interleukin-2 receptor/CD 25 (10/10) was the unifying immunopathologic feature of the neoplasm. Lineage antigens were not identifiable in 8/19 instances (null phenotype), while 10/19 expressed a T-cell phenotype. None of the tumors expressed histiocytic markers. After variable, but intensive, combination chemotherapy, 15 children out of 18 evaluable achieved complete remission (CR). Among all patients, thirteen are still alive in CR (ten in first CR) with a median follow-up of 5 years. This evaluation in the pediatric age group reinforces that so-called MH is a lymphoid neoplasm, a conceptual change that could lead to improved understanding and therapy.