Sinus Histiocytosis with Massive Lymphadenopathy and Unusual Multi-organ Spread: A Case of Rosai–Dorfman Disease

Rosai-Dorfman disease (RDD) is a rare but distinctive clinicopathologic entity of unknown etiology affecting lymph nodes as well as extranodal sites. It was originally described as sinus histiocytosis with massive lymphadenopathy.It is a rare histiocytic proliferative disorder with a distinctive microscopic appearance. A 64 year old female presented with multiple swellings in the neck region. Biopsy from left cervical lymph node favors the finding of Rosai dorfmann disease. CECT of head and neck revealed polypoidal heterogeneously enhancing intracranial lesions in the posterior fossa around right CP angle with multiple enlarged lymph nodal mass at cervical and bilateral parotid stations .Another lesion was seen superficial to sternocleidomastoid muscle and in right orbit. MRI head revealed multiple polypoidal homogeneously enhancing soft tissue lesion in both cerebellar hemispheres and right CP angle. Similar lesions were also seen in right infra orbital space along right lacrimal gland and in left infra orbital space. 18F-FDG PET/CT demonstrated metabolically active lesions involving the bilateral orbits, cervical lymph nodes, right nasopharynx, tail of pancreas, bilateral renal cortices, frontal bone, right acetabulum, right paravertebral muscles, and multiple subcutaneous sites (breast, arm, lumbar region). The patient was started on dexamethasone and methotrexate.