Acute Leukemias Unusual presentation of hairy cell leukemia

A71-year old man was referred to our hospitalbecause of osteolysis of the right femur. Twoweeks before admission he had developed pain, swelling and functio laesa of his right hip. Bone biopsy showed a lymphoid infiltrate, not further typed. A CT scan study showed lytic lesions in the femoral neck and head with a very mild periosteal reaction; extensive demineralization was present with patchy areas of ill-defined sclerosis1 (Figure 1). Phys-ical examination revealed only right hip tenderness; constitutional symptoms were not reported. Hemo-globin and leukocyte counts were normal; his platelet count was 141109/L. At the time of admis-sion, serum alkaline phosphatase, calcium and phos-phorus levels were normal. Abdominal and chest-CT scans showed no abnormal features. Bone marrow aspirate (Figure 2a and 2b) showed a very small pop-ulation (about 2-3%) of ovoid cells which it was not possible to identify by immunophenotyping. Bone marrow biopsy showed a relatively small population of ovoid mononuclear cells with abundant clear cytoplasm. The nuclear chromatin was stippled and nucleoli were not evident. The pattern of bone mar-row involvement was nodular.2 Gomori’s silver stain-ing demonstrated patchy areas of reticulin fibrosis. Intracellular tartrate-resistant acid phosphatase was suggestive of hairy cell leukemia. Hairy cells from the fixed bone marrow biopsy are shown in Figure 2c. The patient was succesfully treated with radiothera-py and interferon-.