In a review of 36 patients, Greene and Rogers 3 noted that the mean age at diagnosis was 39 years and the mean age at onset of symptoms was 33 years. The disease has been reported from different parts of the world and affects the sexes equally. The cause of MRS is unknown, but there may be a genetic predisposition. There is no convincing evidence that MRS is caused by an infective agent such as Toxoplasma gondii , Treponema pallidum , mycobacteria, or herpes simplex virus. Some investigators have tried to link the syndrome to sarcoidosis 10 or Crohn disease.
Facial palsy is a presenting sign in most of the patients with the complete triad.
Orofacial edema has been accepted as the dominant manifestation of MRS and the most important diagnostic feature. Orofacial sites, such as the lips, cheeks, and chin and the buccal, tongue, gingival, or labial mucosal surfaces, may also be affected. It typically affects young adults and is characterized clinically by diffuse, nontender, soft to firm swelling of one or both lips. Histologically, noncaseating epithelioid granulomatous inflammation is characteristic. Noncaseating granulomas are often seen in biopsy specimens of such tissues.