Successful treatment of synchronous hairy cell leukaemia and diffuse large B cell lymphoma in a patient with severe hypercalcemia and extensive osteolytic lesions

Abstract

Introduction: Although secondary malignancies usually occur at different times after HCL treatment, (simultaneous) occurrence of HCL and other malignancies at the same time is very rare. Synchronous hairy cell leukemia (HCL) and diffuse large B cell lymphoma (DLBCL) has not been described so far. Case report: We report a 62-years old female patient who presented with intense constitutional symptoms, hypercalcaemia, pancytopenia and osteolytic destruction of the left shoulder joint. Immunohistochemical analysis of the bone marrow revealed presence of two populations: a population of HCL cells and a population of DLBCL cells with the expression of c-myc and bcl-2 ("double expressor" DLBCL) and high proliferative activity (Ki-67+cells>90%). FISH analysis showed amplification of the bcl-2 gene. In addition, BRAF V600E mutation was detected. After intensive treatment with immunochemotherapy, radiotherapy and bisphosphonates patient achieved complete remission, lasting for more than two years. Conclusion: As the association of hairy cell leukemia and lymphoma is a very rare, diagnosis of synchronous occurrence of two lymphoproliferative diseases is diagnostic and therapeutic challenge. It remains unclear whether DLBC and HCL are derived from two different malignant clones or DLBCL developed by transformation of HCL as the result of clonal evolution of B-cell clone.