Recurrent hairy cell leukemia presenting as a large mesenteric mass diagnosed by fine needle aspiration cytology. A case report.

A case of hairy cell leukemia (HCL) diagnosed by fine needle aspiration (FNA) biopsy performed under computed tomographic (CT) guidance is presented. The patient, who had a three-year history of HCL treated with splenectomy and interferon therapy, had slowly developed increased abdominal girth. A CT scan revealed a large mesenteric mass. FNA was performed on the mass, and immediate microscopic examination of this material revealed numerous neoplastic lymphocytes with morphologic features consistent with HCL. As a result of the preliminary FNA diagnosis, additional appropriate specimens were obtained at the time of the aspiration for confirmatory cytochemical, flow cytometric and ultramicroscopic studies. This case report demonstrates the utility of FNA cytology in the diagnosis of HCL.