Arthritis & Rheumatism, Volume 63,
November 2011 Abstract Supplement
Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Chicago, Illinois November 4-9, 2011.
A Clinicopathologic Study of Retroperitoneal Fibrosis and Its Association with Immunoglobulin G4-Related Disease.
Khosroshahi, Arezou, Hasserjian, Robert P., Sainani, Nisha I., Deshpande, Vikram, Stone, John H.
Background/Purpose:
Retroperitoneal fibrosis (RPF) can be divided into idiopathic and secondary cases. Small studies have suggested that idiopathic RPF can be classified into cases that are associated with histopathologic features of IgG4-related disease (IgG4-RD) and those that are not. We analyzed 23 previously unclassified cases of RPF to evaluate clinicopathological differences between those associated with pathological features of IgG4-RD and those not associated with such features.
Methods:
We searched our pathology service database to identify all patients with RPF diagnosed since 1990. Pathology blocks were available for immunohistochemical analysis on 23 patients. We subclassified RPF cases following chart review into either the idiopathic or secondary categories on the basis of clinical features, and performed immunohistochemical analysis for IgG4 and IgG. RPF cases were classified as IgG4-related if they had IgG4/IgG-positive plasma cell ratios >30%. Histologic features, age, sex, clinical symptoms, location of the fibrosis, and presence or absence of fibrosing lesions at other locations were compared between patients with IgG4-related and non-IgG4-related RPF. The statistical analysis was performed using Fisher's exact test. A probability of P<0.05 was considered statistically significant.
Results:
Nineteen cases were categorized as idiopathic, and four as secondary. Twelve of 19 (63%) idiopathic cases were classified as IgG4-related and 7 (36%) as non-IgG4-related. The clinicopathologic features of these cases are summarized in Table 1. Compared with non-IgG4-related RPF, IgG4-related RPF was more likely to show periaortic involvement and more frequently showed storiform-type fibrosis and eosinophil infiltration. In the IgG4-related cases, the overall mean number of IgG4-positive plasma cells per high-power field (hpf) was 13, a figure much lower than that generally observed in other organs involved with IgG4-RD. The mean IgG4/IgG ratio, however, was 78%.
Table 1. Clinicopathologic features of IgG4-related with non-IgG4-related idiopathic RPF
| IgG4-related (n=12) | Non-IgG4-related (n=7) | Statistical comparison | |
|---|---|---|---|
| Gender (M:F) | 10:2 | 4:3 | NS |
| Age, median (range) | 58 y (38–71) | 64 y (37–72) | NS |
| Periaortic involvement | 10/12 (83%) | 2/7 (28%) | p=0.02 |
| Hydronephrosis | 5/12 (41%) | 5/7 (71%) | NS |
| Aortitis | 2/12 (17%) | 1/7 (14%) | NS |
| Storiform-type fibrosis | 10/12 (83%) | 2/7 (28%) | p=0.02 |
| Eosinophils >5/hpf | 10/12 (83%) | 0/7 (0%) | p<0.001 |
Conclusion:
IgG4-RD accounts for a sizeable subset of patients with RPF. Both histological features and IgG4 immunostaining are critical to the diagnosis of IgG4-RD. Findings of plasma cell infiltration, tissue eosinophilia, and storiform fibrosis should lead pathologists to perform IgG4 immunostains. The IgG4/IgG ratio may be more important in diagnosis than the absolute number of IgG4-positive plasma cells/HPF, particularly when extensive fibrosis is the paramount finding.
To cite this abstract, please use the following information:
Khosroshahi, Arezou, Hasserjian, Robert P., Sainani, Nisha I., Deshpande, Vikram, Stone, John H.; A Clinicopathologic Study of Retroperitoneal Fibrosis and Its Association with Immunoglobulin G4-Related Disease. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :1713
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