Extensive Intra-abdominal Rosai-Dorfman Disease in an Elderly Patient

An 81-year-old female patient presented with a rectovaginal fistula. Imaging suggested sigmoid colon cancer due to an infiltrative lesion at the rectosigmoid junction, extensive extramural vascular invasion, and carcinomatosis affecting the peritoneum and retroperitoneum, encapsulating both kidneys with pelvic lymphadenopathy. The patient underwent laparoscopy with colostomy, followed by a sigmoidoscopy that found no tumors. PET/CT and follow-up MRI revealed widespread nodal and extranodal involvement with soft tissue invasion around both kidneys and multiple peritoneal nodules (Figure). A differential diagnosis included perirenal lymphoma and non-Langerhans cell histiocytosis. A second laparoscopy was performed and the peritoneal biopsy revealed nodular inflammatory infiltrates of lymphocytes, histiocytes, and plasma cells. Immunohistochemistry demonstrated CK emperipolesis+, CD3+, CD20+, CD38+, CD163+, and Ki67 at 8%, confirming Rosai-Dorfman disease (RDD).

Images in an 81-year-old female patient with intra-abdominal Rosai-Dorfman disease. (A) Whole-body maximum intensity projection fluorine 18 fluorodeoxyglucose (¹⁸F-FDG) PET/CT image demonstrates extensive hypermetabolic nodal lesions and perirenal and retroperitoneal soft tissue involvement. (B) Coronal T2-weighted MR image shows bilateral perirenal soft tissue thickening (blue arrows) with bilateral hilar involvement (green arrow). (C) Sagittal T2-weighted MR image shows sigmoid thickening (star) and internal iliac and presacral adenopathy (arrows). (D) Axial diffusion MRI sequence retrospective fused ¹⁸F-FDG PET/MR image demonstrates abnormal glycolytic activity and restricted diffusion of the extranodal lesions (arrowheads).

RDD is a benign inflammatory condition involving non-Langerhans cell histiocytosis, typically affecting children and young adults. Histologically, it is marked by emperipolesis, pericapsular fibrosis, and dilated sinuses filled with histiocytes, lymphocytes, and plasma cells (1). Expression of S100 by histiocytes supports the diagnosis (2). Clinically, RDD presents with painless cervical lymphadenopathy, often accompanied by fever, weight loss, and anemia (3). Over 50% of cases show extranodal involvement, most commonly in the skin and soft tissue (up to 16%), bones (10%), and central nervous system (7%) (4). Abdominal involvement is rare, usually manifesting as liver lesions or retroperitoneal soft tissue infiltrates that can mimic malignancy or infection (4). Asymptomatic patients may be managed conservatively with close follow-up. Symptomatic patients may require low doses of steroids over 3 weeks or high doses for systemic involvement, combined with surgical resection. Other therapies include immunomodulators like sirolimus and rituximab (5).

Keywords: MR-Imaging, PET/CT, PET/MR, Abdomen/GI, Lymphatic, Kidney, Mesentery, Retroperitoneum, Hematologic Diseases, Oncology, Rosai-Dorfman Disease