Idiopathic retroperitoneal fibrosis mimicking malignant lymphoma.
We present a case of atypical idiopathic retroperitoneal fibrosis (iRPF) presenting as a large pelvic tumor, for which it proved difficult to exclude T-cell malignant lymphoma. Histopathological examination of biopsy material showed collagenous tissue and fat with an exuberant and predominant T-cell infiltrate, largely consisting of CD4(+)  cells expressing the IL-2 receptor-α chain (CD25). Focal plasma cells were negative for the immunoglobulin G4 (IgG4) isotype. T-cell receptor gene rearrangement (TRGR) pattern showed a Gaussian distribution, in keeping with a polyclonal T-cell population. Awareness of the sometimes exuberant and predominant T-cell infiltrate in iRPF should lead to earlier consideration of this disorder. This is particularly the case where there is an atypically localized and/or extensive mass, for which early exclusion of monoclonality with TRGR may provide helpful. Immunohistochemical findings suggest that CD4(+) CD25(+)  cells, which are part of a naturally occurring population of regulatory T-cells, may be involved in the pathogenesis of iRPF.
Department of Nephrology, Albert Schweitzer hospital, Dordrecht, The Netherlands. e.f.h.vanbommel@asz.nl
Eric F H
EF
van Bommel
Mark
M
de Mol
Anton W
AW
Langerak
Pieter J
PJ
Westenend
D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001379:Azathioprine / Q000008:administration & dosage; D001706:Biopsy; D002999:Clone Cells; D003937:Diagnosis, Differential; D015329:Gene Rearrangement, T-Lymphocyte / Q000235:genetics*; D006801:Humans; D053645:Interleukin-2 Receptor alpha Subunit / Q000235:genetics* / Q000378:metabolism; D008223:Lymphoma / Q000473:pathology*; D008297:Male; D060885:Multiplex Polymerase Chain Reaction; D016011:Normal Distribution; D010386:Pelvic Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D011239:Prednisolone / Q000008:administration & dosage; D012074:Remission Induction; D012185:Retroperitoneal Fibrosis / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D050378:T-Lymphocytes, Regulatory / Q000473:pathology*; D016896:Treatment Outcome
C508017:IL2RA protein, human; D053645:Interleukin-2 Receptor alpha Subunit; D011239:Prednisolone; D001379:Azathioprine