Rosai-Dorfman Disease

• Also named "sinus histiocytosis with massive lymphadenopathy", unknown etiology.

• Clinical

  • Common in young males, mean age 20.6 years, African-Americans.

  • Leukocytosis, moderate polyclonal hypergammaglobulinemia in most cases.

  • Mostly in cervical LNs, can involve other LNs or extranodal.

  • Painless strikingly enlarged LN.

  • Spontaneous remission in majority

• Histology:

  • Marked sinus expansion filled with lymphocytes, plasma cells, and histiocytes.

  • SHML cells: large and irregularly shaped, abundant acidophilic vacuolated cytoplasm, one nucleus, a central nucleolus.

  • Emperipolesis: The intracytoplasmic vacuoles of SHML cells contain engulfed cells, as many as 20 cells, usually lymphocytes, plasma cells, or erythrocytes. The engulfed cells are usually contained in an intracytoplasmic vacuole. Some cells, particularly lymphocytes in the vacuoles, are viable; others are degraded, often forming nuclear fragments.

  • Lack of mitoses or necrosis.

• IPX: CD14+, CD68+, HLA-DR+, S100+, CD1a-.

• DDX:

  • Sinus histiocytosis: no lymphophagocytosis, S100-.

  • ALCL: atypia, T-cell origin, CD30+,  S100-.

  • LCH: nuclear grooves, eosinophilia, S100+ and CD1a+.