Clinico-pathological profile of Hairy cell leukemia: Critical insights gained at a tertiary care cancer hospital.

Context: Hairy cell leukemia (HCL) is a rare, low grade, B-cell neoplasm with a characteristic morphologic and immunophenotypic profile. It has to be distinguished from chronic lymphoproliferative disorders because of different treatment protocol and clinical course. Aims: To evaluate clinicopathological features including immunophenotypic analysis of cases diagnosed as HCL. Materials and Methods: The present study included 28 cases diagnosed over a period of nine years (2002-2010). Clinical presentation, complete blood count, bone marrow aspirate, and flow cytometric analysis of cases were reviewed. Treatment and follow-up details (ranging from 3-90 months) were noted. Results: This study revealed 28 cases (referrals-7, indoor-21), aged 26-69 years with a median age of 47 years, with a male predominance (M:F=6:1). The presenting complaints were weakness (80%) followed by fever (56%) and abdominal pain. Physical examination revealed splenomegaly in most patients (92%) and hepatomegaly in a minority (28%). The common laboratory features were anemia in 23 cases, pancytopenia in 14 cases, while two patients had leukocytosis and three patients had normal WBC count. Dry tap was observed in 84% of the cases where hairy cells constituted 16-97% of non-erythroid nucleated cells. Tartarte resistant acid phosphate staining was positive in all the eight cases where it was done. CD5 was negative in all the cases, while CD10 was expressed in three cases (13%) and CD23 in five cases (19%). Conclusions: Though pancytopenia is common, occasional patient can present with normal blood counts or leukocytosis. Few unusual findings include presence of lymphadenopathy, absence of palpable splenomegaly, and expression of CD23 and CD10 by the leukemic cells.