Adult Xanthogranuloma, Reticulohistiocytosis, and Rosai-Dorfman Disease.

Adult xanthogranuloma presents most commonly as an orange-tan firm solitary nodule with no systemic manifestations. Recently, some cases have been reported in conjunction with lymphoproliferative disorders. Adult reticulohistiocytosis classically presents as red to yellow-red dermal nodules. In the multicentric form, lesions have a predilection for hands and elbows, with a classic coral bead periungual presentation, and are often associated with symmetric erosive arthritis, particularly of the hands and wrists. The presentation and course of Rosai-Dorfman disease, or sinus histiocytosis with massive lymphadenopathy, can vary. The classic presentation is extensive, painless bilateral cervical lymphadenopathy, but some cases have been entirely extranodal.