A case of cutaneous Rosai-Dorfman disease refractory to imatinib therapy.

BACKGROUND Rosai-Dorfman disease is a non-Langerhans cell histiocytosis that recently has been treated successfully with imatinib mesylate in a patient with a systemic variant of the disease. OBSERVATIONS We describe a 69-year-old man with cutaneous Rosai-Dorfman disease manifesting as progressive, deeply infiltrated skin lesions. Histopathologic examination of the lesions demonstrated dense dermal infiltrate positive for CD68, stabilin-1, and S-100, but not for CD1a. The histiocytes were positive for platelet-derived growth factor receptor alpha, the target molecule for imatinib. During the 5-year course of the disease, multiple therapeutic approaches (tuberculostatic drugs, topical and systemic glucocorticoids, thalidomide, isotretinoin, and methotrexate) did not result in significant improvement. Imatinib mesylate therapy (600 mg/d for 2(1/2) weeks and then 400 mg/d for 10 weeks) had no effect, despite the expression of platelet-derived growth factor receptor alpha on the histiocytes. CONCLUSIONS Failure of imatinib therapy in our patient may be due to a lack of functioning target molecules, the therapy protocol, or the course of the disease. Cutaneous and systemic variants of Rosai-Dorfman disease may be different clinical entities or at least may respond differently to tyrosine kinase inhibitors.