Case Report: Adult Onset Still Disease in a 26-year-old Male.

Introduction: Adult onset still's disease (AOSD) is a systemic inflammatory disease of unknown etiology. It is partially a diagnosis of exclusion, which is why making the diagnosis can be difficult.

Case report: A previously healthy 26-year-old male presented to the clinic following a five-day course of generalized body pain and daily spiking fevers up to 101˚ F. Of note, he reported similar symptoms along with a pink rash on his lower extremities four months prior. These previous symptoms were less severe and lasted one month before spontaneously resolving. Over the span of the next two weeks, his symptoms worsened and he was hospitalized. Physical exam showed a patient in moderately acute distress due to pain. He had generalized abdominal tenderness with questionable hepatomegaly. He had decreased range of motion and strength due to pain in his bilateral upper and lower extremities. His large joints (bilateral shoulders, hips, and knees) were tender to palpation. He also had a new salmon-colored maculopapular rash on his left thigh. PMH, PSH, and FH was noncontributory. He had no known drug allergies and took no medications. Lab work revealed leukocytosis, elevated ESR, elevated haptoglobin, and elevated CRP. All other lab values were within normal limits. Patient met diagnostic criteria for AOSD and was started on high dose prednisone with good response. He was discharged from the hospital, to follow up with rheumatology and his PCP. At a follow up visit with rheumatology, the patient tapered off of prednisone and started on Canakinumab 4 mg/kg (240 mg) subcutaneous injections every 4 weeks. He continued this treatment for five months and had no recurrent symptoms, and injections were discontinued.

Conclusion: In conclusion, AOSD is a rare disease, but should be considered for patients that present with salmon colored maculopapular rash, pharyngitis, arthralgias or arthritis, and fevers.