[Two cases of adult Still's disease with atypical rash]

Adult Still's disease is a febrile disorder of unknown etiology, characterized by spiking fever, arthralgia, leukocytosis and a typical rash. However, most of these clinical findings, except for the typical rash, are not specific to this disease: therefore, the typical rash is the most important clinical finding for diagnosing this disease and physicians often have difficulty in making a definite diagnosis without the typical rash. In our department and related institutions, we have encountered 10 patients with Adult Still's disease who fulfilled the preliminary criteria for classification as Adult Still's disease, proposed by the Adult Still's Research Committee in Japan. The three major criteria are fever, arthralgia and typical rash, and 8 of 10 patients had an atypical rash; one satisfied two major criteria, and had an atypical rash and the other satisfied three major criteria and had an atypical rash on her eyelids. Here, we present the two cases of Adult Still's disease with atypical rash. The first patient was a 36-year-old male with an itchy annular erythema chronicum migrans, frequently seen inpatients with Lyme's disease, on his back. His clinical symptoms improved and the erythema disappeared after treatment with corticosteroids. The second patient, a 17-year-old female, had three major findings. In addition to the typical rash on her face, she had a heliotrope rash, usually seen in patients with dermatomyositis, on her eyelids. The typical rash on her face was related to her other clinical manifestations, and improved after treatment with corticosteroids. However, the rash on her eyelids showed no improvement after steroid therapy, suggesting that the erythema was probably not related to Adult Still's disease. Typical rash in Adult Still's disease, defined as a macular or maculopapular nonpruritic salmon pink eruption, was demonstrated to have the highest relative value associated with relatively high sensitivity and specificity for the diagnosis of Adult Still's disease. However, we have to be aware that some patients with Adult Still's disease could also have an atypical rash.