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Journal of Cancer Research and Therapeutics, Vol. 7, No. 2, April-June, 2011, pp. 214-216 Case Report High-grade plasmablastic neoplasm of humerus in an HIV-negative patient, which was indeterminate between plasmablastic lymphoma and plasmablastic myeloma Santosh Kumar Mondal, Himel Bera, Pranab Kumar Biswas, Mamata Guha Mallick Department of Pathology, Medical College, 88 College Street, Kolkata, West Bengal, India Code Number: cr11053 PMID: 21768719 Abstract Plasmablastic lymphoma (PBL) of bone is a rare neoplasm that shares many confusing cytomorphological and immunohistochemical features with plasmablastic plasma cell myeloma (PBPCM). A 47-year-old female patient presented with a bony swelling and bone pain in the left humerus for the last 6 months. On radiological examination (x-ray and computed tomography) it appeared to be a lytic lesion, and a pathological fracture was detected. The patient was HIV-negative. Fine needle aspiration (FNA) was done from the lesion, which was inconclusive. Subsequently, incisional biopsy was taken. Histopathological examination and immunohistochemistry confirmed a high-grade plasmablastic neoplasm, favoring a diagnosis of PBL. Most of the reported cases of PBL have occurred in HIV-positive patients, and the bone is a very rare site. PBL can be confused with PBPCM. A final diagnosis should be rendered only after thorough histopathological and immunohistochemical examination. Keywords: HIV-negative, plasmablastic type, primary bone neoplasm Introduction In 1997, Delecluse et al. were the first to describe a B-cell lineage neoplasm with plasmablastic differentiation. [1] They called it plasmablastic lymphoma (PBL). They thought that it could be a new sub-group of diffuse large B-cell lymphoma (DLBCL). Initially, it was thought to occur in HIV-positive individuals only, with the most common site of involvement being the oral cavity. Due to scarcity of reported cases of PBL many aspects regarding its manifestation and diagnosis still remain obscure. Often, the correct diagnosis is delayed due to this tumor′s close resemblance to plasmablastic plasma cell myeloma (PBPCM). Bone is an unusual site for PBL. In this case report we present a case of high-grade plasmablastic neoplasm of the humerus, with features favoring a diagnosis of PBL, in an HIV-negative woman. Case Report A 47-year-old woman came to the orthopedic outpatient department complaining of a bony swelling and dull bone pain in upper part of the left humerus for last 6 months. Clinically, the lesion was tender and was fixed to the humerus. The overlying skin was free and unremarkable. Plain radiograph of the humerus showed a radiolucent lesion at the upper part of the shaft. Overall, the appearance was suggestive of a bony tumor. A pathological fracture was also identified on the same x-ray [Figure - 1]a. Subsequent computed tomography (CT) scan revealed a well-defined lytic bone lesion at the same site. No periosteal reaction or matrix calcification was seen. The rest of the bony and cartilaginous structures around the shoulder joint and soft tissue surrounding the tumor were unremarkable. The patient was referred to the cytopathology division of the pathology department for fine needle aspiration cytology (FNAC). Cytologic findings CT-guided FNA was done using a 20-gauge needle [Figure - 1]b. Blood-mixed material was aspirated from the tumor. Smears showed very scanty cellularity, with occasional atypical large cells in a hemorrhagic background. Cytodiagnosis was inconclusive and incisional biopsy was suggested. Histologic findings Grossly, multiple tiny tissue pieces were received. Microscopically, the tumor was composed of large cells with eccentric nuclei and prominent nucleoli in diffuse sheets [Figure - 2]. Mature plasma cells were sparse. The mitotic count was high. On immunohistochemistry, the tumor cells expressed CD138 (strong membrane positivity), CD10, kappa light chain, and MUM-1. They were immunonegative for lambda light chains, CD45, CD20, and CD3 [Figure - 3]. More than 90% of the tumor cells showed nuclear positivity for Ki-67 (proliferative index). Enzyme-linked immunosorbent assay (ELISA) and Western blot test confirmed the HIV-negative status of the patient. Serum electrophoresis did not reveal the presence of any abnormal protein. Bone marrow examination (both aspiration and biopsy) was done. It showed mildly hypercellular marrow, but plasma cells were unremarkable and the plasma cell count was normal. In the present case, Epstein-Barr virus-encoded RNA (EBER) detection was not possible as the patient refused the test. However, based on the high proliferative index, CD10 positivity, and normal bone marrow and serum electrophoresis we made a final diagnosis of high-grade plasmablastic neoplasm, most likely PBL. Treatment was given assuming a diagnosis of PBL. She was treated with six cycles of cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) at intervals of 3 weeks. The patient has now been on follow-up for the 1 year; the past year has been uneventful and she is maintaining her normal life and daily activities. Discussion PBL is an aggressive lymphoma. Ten out of twelve cases studied first by Delecluse et al. died within 12 months of diagnosis. Colomo et al., Flaitz et al., and Nasta et al. have all reported very short survival. [1],[2],[3],[4] The diagnosis of PBL is often complicated due to its close morphologic similarities to PBPCM, with which it also shares many immunohistochemical features. Differentiating PBL from PBPCM is critical, as the treatment is different. Morphologic criteria alone are not enough to differentiate them accurately; rather, a combination of clinical findings plus the results of diagnostic workup are essential for making a definitive diagnosis. As reported by Colomo et al., an increased plasmacytic cell population is seen in PBPCM, whereas PBLs are characterized by extreme paucity or total absence of plasmacytic cells and instead have a monotonous population of plasmablasts. [2] In practice, these morphologic criteria are quite inadequate for distinction between these two entities. According to the studies by Vega et al., both of these conditions are strongly positive (100% for each marker) for CD38, CD138, and MUM-1 and immunonegative for CD20. [5] CD10 is positive for PBL in 67% cases and for PBPCM in only 29% cases. EBER can play a pivotal role in differentiating between PBL and PBPCM. EBER is almost always positive in cases of PBL and negative in PBPCM. [5] Earlier PBL was thought to occur only in HIV-positive cases, particularly in the oral cavity. But, over time, some cases of PBL were also reported in HIV-negative patients. To the best of our knowledge, it was Scheper et al. who reported the first case of plasmablastic lymphoma in an HIV-negative patient; [6] the site of involvement was the oral cavity. Kim et al. reported six cases of PBL from South Korea, with all six patients being HIV-negative; [7] the sites of involvement were the tonsils, nasal cavity, meninges, oral cavity, stomach, and terminal ileum. The authors suggested that perhaps the occurrence of PBL in Koreans is not so intimately associated with HIV status. Primary bone lymphoma itself is a rare neoplasm, constituting only 7% of all malignant bone tumors. [8] Here we report a case of primary bone neoplasm with plasmablastic morphology that was suggestive of PBL. PBLoccurs more commonly in HIV-positive patients and shows a predilection for the oral cavity. Our case was unusual in that the patient was HIV-negative and, besides, an uncommon site was involved, i.e., the humerus. References
Copyright 2011 - Journal of Cancer Research and Therapeutics The following images related to this document are available:Photo images[cr11053f2.jpg] [cr11053f3.jpg] [cr11053f1.jpg] |
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