Rosai-Dorfman Disease : Differential
The differential diagnosis of Rosai-Dorfman disease (RDD) is broad and includes entities that can cause lymphadenopathy. Non-malignant conditions include tuberculosis, Wegener granulomatosis, sarcoidosis, IgG4-related disease, juvenile xanthogranuloma, Erdheim-Chester disease, Gaucher disease, and Langerhans cell histiocytosis. Langerhans Cell Histiocytosis (LCH): The diagnostic features are histiocytes with elongated grooved nuclei, inconspicuous nucleoli, smaller amount of cytoplasm, numerous eosinophils, no plasma cells, no emperipolesis, and positivity for CD1a. BRAF V600E mutations are negative in RDD, whereas they may be found in LCH. Other entities in differential diagnosis include: reactive sinus histiocytosis (absence of massive sinusoidal expansion by histiocytes; no emperipolesis), sinusoidal malignant tumors (atypical cytology; increased mitotic activity; no emperipolesis), lymphomas, melanoma, and hemophagocytic syndromes (disseminated disease; more aggressive clinical course). Cutaneous RDD should be distinguished from eruptive xanthomata (no emperipolesis; S-100 negative), Langerhans cell histiocytosis (small elongated nucleus with grooves, no emperipolesis, epidermotropism, positive for CD1a and langerin), and reticulohistiocytosis (S-100 negative, eosinophilic ground-glass cytoplasm). The image shows RDD in a cervical lymph node. The expanded sinuses contain numerous histiocytes along with lymphocytes and plasma cells.