COW-2019-36

1.  a

1. Rosai Dorfman disease

The lesion has the classic morphology of Rosai Dorfman disease (RDD) with a dense infiltrate of lymphocytes, plasma cells and numerous large histiocytes with abundant cytoplasm. At higher magnification there is lymphophagocytosis by histiocytes (emperipolesis). The histiocytes were positive for S100. CD3, CD20, CD68, CD138 highlight a mixed inflammatory infiltrate. Stains for Kappa and Lambda showed a normal distribution. IgG4 showed 40 cells per HPF with a ratio IgG4/IGG of <10%. The findings in relationship to IgG4 to total IgG ratio are borderline and recommend correlation with serum IgG4 levels. Recently some studies have suggested a relationship between RDD and IgG4 related disease.
Sinus histiocytosis with massive lymphadenopathy was first described by Rosai and Dorfman in 1969, and is commonly referred to as Rosai-Dorfman disease (RDD). As its name implies, RDD is most often encountered in the lymph nodes with the expansion of the sinuses by large histiocytes. However, extranodal involvement can be seen in the skin, soft tissue, bone, or breast, but involvement of essentially every organ/tissue site has been reported. This case is exceedingly rare with no reports in the literature of RDD involving the bladder.
A consensus for clinical management of RDD has recently been established but there is no uniform approach to treatment, with modalities including observation, surgery, steroids, chemotherapy, and immunotherapy depending on the site and presentation. Numerous cases showing RDD have positive IgG4 plasma cells and overlapping histologic features of IgG4-related disease have been reported in multiple other organs including the lungs, head and neck, colon, breast, and skin. Overall, 30% of the RDD cases show varying degrees of fibrosis and increased IgG4 plasma cells. This would be clinically important as IgG4-related disease is treated with steroids and RDD is not

Deshpande V, Zen Y, Chan JK, et al. Consensus statement on the pathology of IgG4-related disease.
Mod Pathol. 2012 Sep;25(9):1181-92.

Tracht J, Reid MD, Xue Y, et al. Rosai-Dorfman Disease of the Pancreas Shows Significant Histologic Overlap With IgG4-related Disease.
Am J Surg Pathol. 2019 Nov;43(11):1536-1546.

Abla OD, Jacobsen E, Picarsic J, et al. Consensus recommendations for the diagnosis and clinical management of Rosai-Dorfman disease.
Blood. 2018;131:2877–2890.

Jonathan Epstein
Johns Hopkins Hospital
jepstein@jhmi.edu

Bladder

IgG4-related disease; Rosai Dorfman disease