Histiocytic lymphophagocytic panniculitis (Rosai-Dorfman disease): a case report.

A 68-year-old woman presented with a symmetrical enlargement of the face and submandibular area associated with essential thrombocytosis. Biopsy of the lesions revealed a septal and lobular panniculitis disclosing a lymphohistiocytic and plasma cell proliferation with lymphophagocytosis by histiocytes, compatible with Rosai-Dorfman disease. The lesions regressed spontaneously without therapy over a period of 4 months. Diagnosis was confirmed by electron-microscopic examination and immunocytochemical presence of S-100 antigen within the histiocytic cells. A 2-year follow-up did not demonstrate any evidence of recurrence.