Anaplastic large cell lymphoma (ALCL) presenting as primary bone and soft tissue sarcoma--a study of 12 cases.

This study highlights the rare presentation of anaplastic large cell lymphoma as primary bone and soft tissue tumour. Twelve cases were studied. Clinical impression was non Hodgkin's lymphoma in 4 cases, sarcoma in 6 (osteosarcoma-2, Ewing's/primitive neuroectodermal tumour-1, and sarcoma NOS-3), and tuberculosis of thoracic spine in 1 and the last case involving the rib had a differential diagnosis of tuberculosis and NHL. Histology revealed round cells with eosinophilic cytoplasm and pleomorphic nuclei. Immunohistochemically all tumours were CD30 positive and 8 of 9 cases (88.9%) showed ALK-1 positivity. The pleomorphic cytomorphology ofALCL leads to confusion with the more frequent bone and soft tissue sarcomas affecting the musculoskeletal system. A high index of suspicion is necessary to initiate the correct panel of immunohistochemical markers to first confirm the lymphomatous nature of this tumour and to subsequently subclassify. This alone will lead to an accurate recognition of ALCL and the appropriate chemotherapy.