Hairy Cell Leukaemia in Oman: Four cases.

Hairy cell leukaemia (HCL) is a rare, clonal, chronic lymphoproliferative disorder commonly seen in males in the middle years of life. Pancytopaenia with moderate to massive splenomegaly is the most common clinical presentation. Diagnosis is made on detecting the lymphocytes with abundant cytoplasm which spread into hair-like processes on peripheral blood and bone marrow smears, thus giving the name, "hairy cell leukaemia". The bone marrow aspirate is frequently a dry tap. The trephine biopsy has the characteristic features of a honey comb appearance and flow cytometry is typically CD103, CD25, FMC7, CD11c, gamma or kappa light chain positive with the classic B lymphocyte markers CD19, CD20, CD79a. Purine analogues followed by granulocyte-colony stimulating factor (G-CSF) to manage the febrile neutropenia is currently the treatment of choice. A 10 year disease free survival is recorded with these management strategies. Experimental use of anti CD20 and CD22 has also shown promising results in the treatment of this disease. We report four cases of HCL diagnosed in a span of two years at the Royal Hospital, Muscat, Oman.