Sinus Histiocytosis with Massive Lymphadenopathy (Rosai-Dorfman Disease)
Lessons From the Friday Unknowns
Histologic examination shows fragments of tissue with distinct pale areas divided by amphophilc strips.
The pale areas show a proliferation of histiocytes with clear, balloon-like cytoplasm, demonstrating scattered emperipolesis. The amphophilic strips are filled with mature plasma cells with scattered Russell bodies. Background few scattered small lymphocytes are also visualized.
Immunohistochemical (IHC) stains show histiocytes are positive for S100 and CD68, and stains highlight emperipolesis of various cells, including plasma cells.
CD138 highlights plasma cells, with no definite light chain restriction by kappa and lambda stains with very high background.
Overall, morphologic and immunophenotypic findings are diagnostic for sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease).
Link to digital slides: https://bit.ly/3iw6W7Y | Slides labeled case 4