Plasma cell leukemia with t(11;14)(q13;q32) simulating lymphoplasmacytic lymphoma – a diagnostic challenge solved by flow cytometry

Plasma cell leukemia (PCL) is a rare and aggressive manifestation of malignant plasma cell proliferation and corresponds to 2–4% of multiple myeloma (MM) cases.1,2 The World Health Organization (WHO) defines PCL by the presence of high levels (at least 2 × 109/L) of clonal plasma cells in the peripheral blood (PB) or at least 20% of the leukocyte differential count.1 Primary PCL (pPCL) corresponds to 60% of the cases and presents as leukemia at diagnosis, usually with tissue infiltration, organomegaly and lymphadenopathy and a lower frequency of bone lesions (15–40% cases) than multiple myeloma.2 Secondary PCL is the terminal phase of MM and corresponds to the remaining 40% of PCL cases; it usually has a poor response to standard MM treatment.2,3 The diagnosis of plasma cell neoplasms is easily suggested by the characteristic plasma cell