Neutrophil-rich anaplastic large cell lymphoma of the skull presenting after head trauma

The presentation of anaplastic large cell lymphoma in bone is uncommon. We report a case of anaplastic large cell lymphoma of the skull that was diagn osed after head trauma. Biopsy revealed significant destruction of the oute r table of the frontal bone. Histopathologically, the initial evaluation su ggested osteomyelitis because of a mixed inflammatory infiltrate with large numbers of neutrophils. However, several clusters and individual mononucle ar cells were atypical. The tumor cells had large, pleomorphic nuclei; thes e cells stained positively with antibodies to Ki-l (CD 30), ALK-1, and EMA. Fluorescence in situ hybridization (FISH) showed rearrangement of the ALK gene, which usually results from the t(2;5) translocation, present in most anaplastic large cell lymphomas. There was no evidence of systemic disease. The patient has tolerated chemotherapy and is free of disease 12 months la ter.