Splenic marginal zone lymphoma pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [9]
Overview
Pathophysiology
Splenic marginal zone lymphoma (SMZL) is a lymphoma comprised of B-cells that replace the normal architecture of the white pulp of the spleen. The neoplastic cells are both small lymphocytes and larger, transformed blasts, and they invade the mantle zone of splenic follicles and erode the marginal zone, ultimately invading the red pulp of the spleen. Frequently, the bone marrow and splenic hilar lymph nodes are involved along with the peripheral blood. The neoplastic cells circulating in the peripheral blood are termed villious lymphocytes due to their characteristic appearance.[1]
Sites of Involvement
Aside from the uniform involvement of the spleen, the bone marrow is frequently positive in patients with SMZL. Nodal and extranodal involvement are rare.[1]
Splenic Hilar Lymph Nodes
Involved hilar lymph nodes adjacent to the spleen show an effaced architecture without preservation of the marginal zone seen in the spleen.[1]
Bone Marrow Biopsy
SMZL in bone marrow displays a nodular pattern with morphology similar to what is observed in the splenic hilar lymph nodes.[2]
Peripheral Blood
Circulating lymphoma cells are sometimes present in peripheral blood, and they occasionally show short villi at the poles of cells and plasmacytoid differentiation.[3]
Molecular Findings
Immunophenotype
| Antigen | Status |
|---|---|
| CD20 | Positive |
| CD79a | Positive |
| CD5 | Negative |
| CD10 | Negative |
| CD23 | Negative |
| CD43 | Negative |
| cyclin D1 | Negative |
The relevant markers that define the immunophenotype for SMZL are shown in the table to the right.[4][5] The lack of CD5 expression is helpful in the discrimination between SMZL and chronic lymphocytic leukemia/small lymphocytic lymphoma, and the lack of CD10 expression argues against follicular lymphoma. Mantle cell lymphoma is excluded due to the lack of CD5 and cyclin-D1 expression.[6]
Genetics
Clonal rearrangements of the immunoglobulin genes (heavy and light chains) are frequently seen.[7] The deletion 7q21-32 is seen in 40% of SMZL patients, and translocations of the CDK6 gene located at 7q21 have also been reported.[8]
References
- ↑ 1.0 1.1 1.2 [1] Jaffe E.S., Harris N.L., Stein H., Vardiman J.W. (eds): World Health Organization Classification of Tumors. Pathology and Genetics of Tumours of Haemopoietic and Lymphoid Tissues. IARC Press: Lyon 2001
- ↑ [2] Franco V, Florena AM, Campesi G. "Intrasinusoidal bone marrow infiltration: a possible hallmark of splenic lymphoma." Histopathology. 1996 Dec;29(6):571-5. PMID: 8971565
- ↑ [3] Melo JV, Hegde U, Parreira A, Thompson I, Lampert IA, Catovsky D. "Splenic B cell lymphoma with circulating villous lymphocytes: differential diagnosis of B cell leukaemias with large spleens." J Clin Pathol. 1987 Jun;40(6):642-51. PMID: 3497180
- ↑ [4] Isaacson PG, Matutes E, Burke M, Catovsky D. "The histopathology of splenic lymphoma with villous lymphocytes." Blood. 1994 Dec 1;84(11):3828-34. PMID: 7949139
- ↑ [5] Matutes E, Morilla R, Owusu-Ankomah K, Houlihan A, Catovsky D. "The immunophenotype of splenic lymphoma with villous lymphocytes and its relevance to the differential diagnosis with other B-cell disorders." Blood. 1994 Mar 15;83(6):1558-62. PMID: 8123845
- ↑ [6] Savilo E, Campo E, Mollejo M, Pinyol M, Piris MA, Zukerberg LR, Yang WI, Koelliker DD, Nguyen PL, Harris NL. "Absence of cyclin D1 protein expression in splenic marginal zone lymphoma." Mod Pathol. 1998 Jul;11(7):601-6. PMID: 9688179
- ↑ [7] Dunn-Walters DK, Boursier L, Spencer J, Isaacson PG. "Analysis of immunoglobulin genes in splenic marginal zone lymphoma suggests ongoing mutation." Hum Pathol. 1998 Jun;29(6):585-93. PMID: 9635678
- ↑ [8] Corcoran MM, Mould SJ, Orchard JA, Ibbotson RE, Chapman RM, Boright AP, Platt C, Tsui LC, Scherer SW, Oscier DG. "Dysregulation of cyclin dependent kinase 6 expression in splenic marginal zone lymphoma through chromosome 7q translocations." Oncogene. 1999 Nov 4;18(46):6271-7. PMID: 10597225