[1314] Nodular Pattern of Bone Marrow Infiltration by Diffuse Large B-Cell Lymphoma: Clinicopathologic Characteristics

EM Weeden, DW Sevilla, S Alexander, VV Murty, B Alobeid, G Bhagat. Columbia University, New York, NY

Background: Different patterns of bone marrow (BM) infiltration by diffuse large B-cell lymphomas (DLBCL) have been described. A pure nodular pattern is considered uncommon and is not well-characterized. We thus undertook this study to assess the morphology, phenotype, cytogenetic abnormalities, and clinical features of DLBCL associated with this pattern.
Design: We searched our departmental database to identify BM biopsies (bxs) involved by DLBCL from 1997-2008. H&E stained sections were reviewed to characterize the pattern of BM involvement and identify cases with a discrete nodular pattern. Immunohistochemical stains and in situ hybridization for EBER were performed on all cases. Patient demographics and clinical data were obtained from our laboratory information system.
Results: A pure nodular pattern of infiltration was noted in 12/52(23%) BM bxs involved by DLBCL. We identified 7 cases of EBV+ DLBCL, of which 6 (86%) showed a nodular pattern. Only 6 of the 45 EBV- DLBCL (13%) demonstrated nodular infiltration (p=0.00028). The nodules in all 6 EBV+ DLBCL (4M, 2F, aged 3-72 yrs, median 60 yrs) had rounded contours, numerous admixed histiocytes, without obvious angiocentricity. In 4/6(67%) cases, the neoplastic cells were pleomorphic and scattered Reed-Sternberg like cells were present. 2/6(33%) cases showed centroblastic morphology. All had non-germinal center (GC) phenotype. In contrast, the nodules of 6 EBV- DLBCL (3M, 3F, aged 54-84 yrs, median 64 yrs) had irregular contours and fewer admixed histiocytes. The neoplastic cells had centroblastic (n=6) morphology; 4/6(66%) and 2/6(33%) had non-GC and GC phenotype, respectively. 5/6(83%) EBV+ DLBCL expressed CD30 compared to 1/6(17%) of EBV- DLBCL (p=0.4). No recurrent cytogenetic abnormalities were detected in either the EBV+ or EBV- DLBCL. All patients with EBV+ nodular DLBCL were immunocompromised (2 HIV+, 3 post transplant lymphoproliferative disorders, 1 old age), compared to only 1/5(20%) individuals with EBV- nodular DLBCL (old age).
Conclusions: A pure nodular pattern of BM infiltration by DLBCL is not infrequent (23%) and the vast majority of such cases have a non-GC phenotype (83%). We observed a marked enrichment of EBV+ pleomorphic DLBCL occurring in immunocompromised patients with a significant propensity to involve the bone marrow in a purely nodular pattern. This association suggests that evaluation for EBV infection and investigation into the patient's immune status is warranted when a nodular pattern of BM infiltration is encountered.
Category: Hematopathology

Monday, March 9, 2009 9:30 AM

Poster Session I Stowell-Orbison/Autopsy Award # 194, Monday Morning