Analysis Of Clinicopathological Characteristics Of Plasmablastic Lymphoma

Background and objective:PBL was first described in1997as a rare subtype of DLBCL with an aggressiveclinical behavior that arises in the oral cavity of HIV-infected individuals. PBL is a distinct,aggressive B cell lymphoma. These cells resemble B immunoblasts morphologically buthave a plasma cell immunophenotype. With increased understanding of the clinicalspectrum of this disease and its biology, PBL was subsequently identified in patientswithout HIV infection. Castillo and his colleagues conducted an extensive literature searchusing PubMed/MEDLINE from January1997through August2009for articles in alllanguages reporting cases with a histological and/or pathological diagnosis of PBL,gathering228PBL cases, from which,157were HIV-positive and71were HIVnegative.Kim and and his colleagues reported6PBL cases without HIV-infection in2009. However,in China, there are only a few sporadic case reports which cannot illustrate thecharacteristics of PBL in China systematically. In this study, we conduced a retrospective analysis of11cases of PBL in Chinese patients to elucidate its clinicopathologiccharacteristics.Methods:This study included11cases with a pathologic diagnosis of PBL treated at theDepartment of Hematology of Xijing Hospital, Xi’an, China, from October1,2009toNovember1,2012.1. Relevant clinical and laboratory materials were reviewed and analyzed.2. Hematoxylin-eosin staining and immunohistochemical studies were performed onformalin-fixed, paraffin-embedded tissue sections prepared from samples obtained fromthe PBL cases, respectively.3. EBV-infection was assessed by in situ hybridization (ISH) analysis of EBV-encodedRNA (EBER) performed on formalin-fixed paraffin-embedded tissue sections using aNovocastra ISH kit according to the manufacturer’s instructions.4. Fluorescence in situ hybridization (FISH) analysis was performed using the MYCprobe (LSI MYC Dual Color, Break-Apart Rearrangement probe) to investigate and/orconfirm the presence of MYC gene rearrangements.100to200nuclei were examined forprobe signal scoring for each sample. The cut-off values were estimated at3%for thedetection of the rearrangements, and6%to detect amplifications.Results:1. The median age at diagnosis was51.4years (range,24–76). The male-to-femaleratio was1.75:1(7male and4female cases). The stage at diagnosis varied from I to IV.Of the11patients, primary sites of presentation included the oral cavity (1), lymph nodes(3), intraspinal mass (1), paranasal sinuses (1), larynx (1), breast (1), adrenal gland (1),vagina (1) and soft tissues (1). The secondary sites of involvement of the11patients wereas follows: lymph nodes (4), bone marrow (4), liver (3), bone (2), spleen (2), kidney (2),orbit (1) and adrenal glands (1). B symptoms were present in5patients. All patients wereHIV-negative and immunocompetent at the time of diagnosis with two patients havingpre-existing disease; one patient had a bone tumor in2002and received lower limbsurgery later and another had suffered from hepatitis B for decades. Median follow-up time was3.9months (range,1.9–41.0months) and the median overall survival time was5.0months.2. Histopathological analysis of submitted tissue biopsies showed that tumor cells wereround or oval. These cells were abundant in the cytoplasm and showed basophilic staining.The nuclei were round or oval and located centrally or eccentrically. Binucleate ormultinucleate tumor cells were occasionally found, ranging from immunoblastic toplasmablastic differentiation. All cases expressed at least one plasma cell marker and werenegative for the B cell marker CD20(11/11). Furthermore, a subset of cases showednegative immunoreactivity to the other B cell markers (PAX5:9/11, CD79a:6/10). Eight(8/11) patients were negative for CD10. CD30was detected in six (6/11) cases, of whichonly one was weakly positive; five (5/11) patients were negative. Eight (8/11) patientswere negative for CD56and five (5/11) patients were positive for CD45, while three werepositive and two weakly positive. All patients were negative for ALK. The Ki67proliferative index exceeded60%in all cases, with a mean value of73%.3. Five cases showed strong hybridization signals in neoplastic cells.4. FISH studies confirmed MYC gene aberrations in two cases; these were identifiedas gene rearrangements and duplications.Conclusion:1. Some similarities in clinical features compared with those reported for Westernpopulations were found in the Chinese cohort in this study. First, these cases were almostin advanced stage when diagnosed. Second, despite a good response rate, Chinese patientshad a poor overall survival. Last, these cases had various distribution of extranodalinvolvement.The difference was that these Chinese PBL patients showed no relationshipwith HIV infection or immunosuppression. Besides, as we reported the first case ofHIV-negative PBL with initial presentation of the vagina stump, it should be included as adifferential diagnosis in cases of suspected vaginal stump tumor.2. These11cases showed typical morphological and immunohistochemical features ofPBL.3. Chinese PBL patients showed a lower EBV-infection rate comparing with western patients.4. Chinese PBL patients showed a lower MYC aberration rate comparing with westernpatients.