Rosai–Dorfman Disease: A Rare Disease with Uncommon 18F-FDG PET CT Findings

Introduction

We present the case of a 28-year-old female who presented with nasal obstruction for 3–4 months and did not respond to any treatment. Nasal endoscopy showed a soft-tissue lesion in the nasal cavity. She also presented with painless nodules in multiple sites of the body and a gradual onset of pain over the foot. On clinical examination, cervical and axillary lymph nodes were found and advised for biopsy. Cervical lymph node biopsy showed distended lymph node sinuses containing histiocytes as a prominent component. They are characterized by large, round nuclei and voluminous cytoplasm showing emperipolesis with engulfment of lymphocytes. The lymphoplasmacytic infiltrate within the lymph node parenchyma is cytologically unremarkable. Immunohistochemistry (IHC) shows that the atypical histiocytes are positive for CD68, CD163 with coexpression of S100, OCT2, and cyclin D1 and negative for CD1a and langerin. CD3 and CD20 reveal an appropriate mixture of T cells and B cells, respectively, suggestive of the reactive pattern. These histological features and IHC findings led to a diagnosis of Rosai–Dorfman disease (RDD). The patient was sent to us for a positron emission tomography/computed tomography (PET/CT) scan to determine the extent of the disease. Whole-body 18 F-fludeoxyglucose PET/CT showed metabolically active soft-tissue lesions in the nasal cavity, multiple hypermetabolic lymph nodes on both sides of the diaphragm (bilateral cervical, axillary, and inguinal pelvic), multiple marrow/skeletal lesions and cutaneous nodules [Figure 1a-k]. There was also left paravertebral thickening at the D6 vertebral level, with intraspinal extension [Figure 1l and m].

Close

Figure 1 A 28-year-old female known case of Rosai–Dorfman Disease was referred to us for positron emission tomography/computed tomography (PET/CT) scan image (a) shows an MIP image showing fludeoxyglucose (FDG) uptake in bilateral cervical, axillary, iliac and inguinal regions, uptake in nasal region and bilateral legs, (b and c) shows transaxial images fused PET/CT and CT of nasal cavity lesion with few subcutaneous nodules in the bilateral arm, (d and e) bilateral cervical lymph nodes, (f and g) right axillary lymph nodes, (h and i) iliac lymph nodes with a cutaneous nodule in the left gluteal region. (j and k) showing transaxial images fused PET/CT and CT of the distal leg showing increased FDG uptake with a subtle lytic lesion in the right distal tibia and left fibula, (l and m) shows transaxial images of fused PET/CT and CT images of paraspinal FDG uptake at D6 vertebral level highlighted by the blue arrow

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RDD, also called sinus histiocytosis with lymphadenopathy, is a rare benign histiocytic proliferative disorder of unknown etiology and was first described in 1969 with the incidence of 1 in 200,000.[1] It typically affects older females and the most common presentation is with massive lymphadenopathy and nonspecific systemic symptoms; therefore, it is often confused with lymphoproliferative disorders.[23] Most commonly Patients with classical RDD present with bilateral cervical lymphadenopathy, but 43% of patients with RDD present with extranodal disease.[4] Extranodal affected sites include the skin, central nervous system, orbital tissues, nasal cavity, paranasal sinuses, intrathoracic lesions, and bones.[5]

In this case, there is both extranodal and nodal involvement. There is involvement of lymph nodes on both sides of the diaphragm, nasal cavity, characteristic cutaneous nodules, and skeletal and marrow. It mimics the findings of lymphoma. In this case, it has a spectrum of disease involvement, including skin, bone, nasal cavity, and paraspinal lesion. In bone involvement cases, cranial and facial bone involvement is common followed by tibia. However, involvement of the other bone is rarely encountered.[6] In head-to-toe acquisition, there is involvement of the right femur marrow lesion, right tibia, and left fibular signifying head-to-toe acquisition in RDD helps in identifying the extra site of involvement. Baseline PET/CT before therapy can help in response assessment and finding out the extent of disease. Bone involvement in RDD is <10%.[4] This case highlights the rare involvement of the tibia, talus, and fibula with no other axial bone involvement and most of extranodal involvement in a single case.