Indian Journal of Hematology and Blood Transfusion | 2019
Plasmablastic Lymphoma Versus EBV-Positive Myeloma
Abstract
Hematolymphoid neoplasms with plasmablastic lymphoma (PBL) and plamablastic/anaplastic myeloma (PBM) show significant morphological and/or immunophenotypic overlap which may make it very difficult for pathologists to make a definite and specific histopathological diagnosis [1]. Features such as renal dysfunction, significant paraprotein, osteolytic bony lesions, hypercalcemia and diffuse bone marrow involvement favor a diagnosis of PBM. In contrast, EBER expression in neoplastic cells, HIV coinfection and high proliferative index support a diagnosis of PBL. When myeloma-defining signs are incomplete or absent, the presence of oropharyngeal soft tissue lesion or lymphadenopathy favor a diagnosis of PBL, regardless of bone marrow disease. The distinction is very important as the treatment of these entities differ remarkably. PBL is an aggressive disease with relapsing clinical course and has higher rates of disease progression and fatality despite use of state of the art treatment modalities. Current guidelines recommend intensive regimens such as EPOCH (infusional etoposide, vincristine, doxorubicin with bolus cyclophosphamide and prednisolone) and Hyper-CVAD (hyperfractionated cyclophosphamide, vincristine, doxorubicin and dexamethasone alternating with methotrexate and cytarabine). On the other hand, myeloma is managed with Bortezomib-based regimens followed by autologous stem cell transplantation (ASCT). Despite extensive work-up, few cases remain to be classified into any of the two categories and thus are labelled as Indeterminate [2, 3]. We present one such case with overlapping features thereby making the diagnosis very intriguing. A 62 year old male presented with sudden onset breathlessness for 15 days. On examination, he had pallor and splenomegaly. Hemogram showed Hb: 8 g/dl, TLC: 8100/cumm and Platelet count: 154,000/cumm. PS showed rouleaux formation with presence of 9% plasmacytoid cells. Viral markers for HIV, HCV, HBV were negative; serum calcium was within normal limits. Serum creatinine was raised (4.3 mg/dl). PET-Scan showed bone marrow infiltrative disease along with mild splenomegaly in the absence of any lymphadenopathy or soft tissue masses. Skeletal survey was unremarkable. Serum b2-microglobulin was raised (27.8 mg/L) and serum albumin was 3.6 g/ dl. Serum electrophoresis revealed M band of 3.5 g/L in gamma region. Serum immunofixation showed a strong band in IgG/Kappa region. Bone marrow examination revealed near-total replacement of normal hematopoietic components by plasmablasts and large bizarre cells with anaplastic features admixed with scattered bi/multinucleated forms. Immunohistochemistry revealed diffuse and strong positivity for CD138 and CD38 with clonal restriction for Kappa light chain and negative expression of PAX-5, CD20, CD3, CD56, ALK-1 and lambda light chain with Ki-67 index of 5–10%. Cytogenetics revealed normal karyotype. Expression of EBER by in situ hybridization technique was strongly positive (Fig. 1). Diagnosis of PBM was favored over PBL on the basis of following features: (a) very low proliferative index (PBL have higher values in the range of 80–100%). (b) presence of two CRAB features i.e. anemia and renal failure (c) diffuse bone marrow & Neha Singh [email protected]