Rosai-Dorfman Disease

(See also Overview of Histiocytic Disorders.)

Rosai-Dorfman disease (RDD) is most common among patients < 20 years, particularly people of African descent. In 2022, the World Health Organization classified RDD as a myeloid neoplasm due to mutations in the mitogen-activated protein kinase (MAPK) pathway (1).

The most common presenting symptoms are

• Fever

• Massive, painless cervical lymphadenopathy

Other nodal sites, including the mediastinum, retroperitoneum, axillae, and inguinal region, may be involved, as may the nasal cavity, salivary gland tissue, other regions of the head and neck, and the central nervous system. Other manifestations may include lytic bone lesions, pulmonary nodules, and rash. The bone marrow and spleen are typically spared.

Laboratory testing usually shows leukocytosis, polyclonal hypergammaglobulinemia, hypochromic or normocytic anemia, and an elevated erythrocyte sedimentation rate. Biopsy usually whows accumulation of histiocytes with enlarged, round to oval hypochromatic nuclei and abundant eosinophilic cytoplasm, often containing engulfed intact inflammatory cells (a phenomenon known as emperipolesis) (2). Next generation sequencing should be done to identify mutations that can be targeted.

The disorder commonly resolves without treatment. In patients with progressive disease, chemotherapy and mitogen-activated protein kinase (MAPK) pathway inhibition and mTOR inhibition (rapamycin) have been used (3, 4, 5).