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. © 2011 The Authors. Pathology International

, , ,
doi.org/10.1111/j.1440-1827.2011.02718.x, hdl.handle.net/1765/34287
Pathology International
Erasmus MC: University Medical Center Rotterdam

van Bommel, E., de Mol, M., Langerak, A., & Westenend, P. (2011). Idiopathic retroperitoneal fibrosis mimicking malignant lymphoma. Pathology International. doi:10.1111/j.1440-1827.2011.02718.x