184 Primary Dural Marginal Zone Lymphoma: Report of Two Cases With Large Cell Transformation and Complex Cytogenetics

• Published in: American journal of clinical pathology 2018-01, Vol.149 (suppl_1), p.S78-S79
• Main Authors: Wooldridge, Jacob, Oladipo, Olajumoke, Sayedian, Farzaneh, Qian, Youwen
• Format: Article
• Language: English
• Subjects: Bcl-2 protein; Bcl-6 protein; Brain cancer; c-Myc protein; CD5 antigen; Cell proliferation; Central nervous system; Chemotherapy; Clonal deletion; Cytogenetics; Differential diagnosis; Flow cytometry; Genetic transformation; Immunohistochemistry; Lymphocytes B; Lymphoma; Metastases; Myc protein; Parenchyma; Radiation therapy; Transformed cells
• ISSN: 0002-9173; 1943-7722
• DOI: 10.1093/ajcp/aqx121.183

Abstract Introduction Dural marginal zone lymphoma (DMZL) is a very rare type of central nervous system lymphoma that does not involve brain parenchyma. The differential diagnosis includes meningiomas and metastasis, which can make the diagnosis difficult. DMZL has been considered indolent lymphoma in the literature. Here we report additional two new cases of DMZL; one had transformation to diffuse large B-cell lymphoma (DLBCL), while the other had complex cytogenetics, indicating the potential for DLBCL transformation, and genetics associated with unfavorable prognosis for this unusual lymphoma location. Methods Routine histology, flow cytometry immunophenotyping, immunohistochemistry, karyotyping, and FISH analysis were employed for these two cases. Results Histologic findings are slightly different in these two cases. Besides morphologic changes consistent with a marginal zone lymphoma, one case had areas of sheet of large transformed cells, which suggested transformation to DLBCL, as illustrated by high Ki-67 proliferation index up to 80%-90% in the large cell areas. Flow cytometry detected a population of kappa-restricted monoclonal B cells without CD5 or CD10 for both cases. Karyotyping for the second patient showed that of the 20 cells analyzed, eight were normal, and 12 had multiple clonal abnormalities including a del 6q, additional material of unknown origin attached to 17q, and an unbalanced structural rearrangement involving an 18q resulting in 18q deletion and duplication of 1q (karyotyping: 46,XX,del(6)(q21q23),add(17)(q25),der(18)t(1;18)(q21;q23)[12]/46,XX[8]). FISH probes for c-MYC, BCL-2, BCL-6, and CCND1 were all negative for both cases. The first patient with DLBCL was treated with adjuvant radiation therapy after the completion of chemotherapy. The patient with complex karyotyping was found local recurrence after surgical mass removal for which she had received local radiation therapy. Both patients are still alive. Conclusions DMZL, although considered a low-grade lymphoma, may have DLBCL transformation or complex cytogenetics, despite the unusual location.