Idiopathic vs. secondary retroperitoneal fibrosis: a clinicopathological study of 12 cases, with emphasis to possible relationship to IgG4-related disease
Abstract
Retroperitoneal fibrosis (RF) is a rare disease characterized by inflammation and fibrosis of retroperitoneal soft tissues. It is classified into 2 types: idiopathic (iRF), and secondary (sRF).
The aim of the study was to investigate the relationship between iRF and IgG4-related disease (IgG4-RD) and to eventually extend the clinicopathological features of this condition by analysis of the sample comprising 6 iRF- and 6 sRF-patients. The iRF-patients included 4 males and 2 females, aged 12-62 years (median 55 years).
Two lesions were periaortic, 1 was periureteral and 3 cases showed both periaortic and periureteral localization. Two patients had increased serum levels of IgG4.
None of the patients developed any manifestation of IgG4-RD during the follow-up period ranging for 15 – 133 months (median 43 months). Microscopically, in 2 iRF-cases fibrosis was highly cellular encircling vessels, nerves and paraganglia.
Phlebitis was found in all cases being obliterative in 4. Lymphocytic inflammation with formation of follicles and plasma cell infiltration were scored as severe in 5 iRF-cases.
The numbers of IgG-positive plasma cells ranged 0-373 per 1 HPF (median 132) and of IgG4-positive plasma cells 0-238 per 1 HPF (median 91). The IgG4/IgG ratio values ranged 0.38-0.74 (median 0.68).
Two of the iRF-cases were diagnosed as definite and 3 cases as probable IgG4-RD. To the contrary, none of the sRF-cases met the diagnostic criteria for either definite, probable or possible IgG4-related disease.
Our results indicate that a substantial portion of iRF-cases, including some of very rare pediatric cases, is a manifestation of IgG4-RD