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Lymphoma - B cell neoplasms

B cell lymphoma subtypes

Mediastinal (thymic) large B cell lymphoma subtype


Reviewer: Nikhil Sangle, M.D., University of Utah and ARUP Laboratories (see Reviewers page)
Revised: 27 February 2011, last major update February 2011
Copyright: (c) 2001-2011, PathologyOutlines.com, Inc.

Definition
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● A type of diffuse large B cell lymphoma, often presents as antero-superior mediastinal mass, superior vena cava syndrome or tracheobronchial compression
● Absence of lymph node or bone marrow involvement essential to exclude secondary involvement by diffuse large B cell lymphoma

Epidemiology
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● Young adults, 2/3 female

Etiology
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● May derive from thymic medullary B cells or from germinal center (Am J Surg Pathol 2001;25:1277)

Clinical features
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● Aggressive; 50% present with stage 1 or 2 disease
● Poor prognosis, with adjacent thoracic visceral involvement, pleural or pericardial effusion
● 5 year survival is 50%, with relapses to kidney, breast, adrenal cortex, ovary, liver, pancreas, GI

Gross
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● Large, bulky, locally invasive, often fibrotic

Micro description
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● Pleomorphic large cells including centroblasts and immunoblasts with abundant cytoplasm and distinct cell borders
● Oval, cleaved or multilobated nuclei resembling Reed-Sternberg cells
● Also histiocytes, small lymphocytes, sclerosis
● Variable residual thymic tissue

Positive stains
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● CD19, CD20, CD45, CD79a
● Also CD22, bcl6
● Lacks surface immunoglobulin expression (Am J Path 1995;146:735)
● Variable CD10 (33%), CD23, CD30, CD45, TdT
● Rarely beta-hCG (Am J Surg Pathol 1999;23:717)

Negative stains
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● CD3, CD5, CD15, CD21

Molecular
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● Clonal IgH and IgL rearrangements, 9p24 and 2p15 amplification involving REL and BCL11A genes respectively

Differential diagnosis
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● Hodgkin’s lymphoma, lymphoblastic lymphoma, germ cell tumors, thymoma

End of Lymphoma - B cell neoplasms > B cell lymphoma subtypes > Mediastinal (thymic) large B cell lymphoma subtype


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