An Initially Missed Diagnosis of Venous Thromboembolic Phenomenon in Adult-Onset Still's Disease: A Case Report and Literature Review.

BACKGROUND Still's disease is a rare multisystemic autoinflammatory disorder. The diagnosis of adult-onset Still's disease (AoSD) can be challenging due to the rarity and overlapping features with many other systemic disorders. Complications of the illness can involve many systems in the human body. One of the least documented hematological complications of AoSD is thromboembolic phenomena. CASE REPORT This text outlines the presentation of a 43-year-old woman with a known diagnosis of AoSD, whose disease-modifying anti-rheumatic drugs (DMARDs) had been tapered and stopped due to remission. She presented with respiratory symptoms and features of an AoSD flare. Lack of complete improvement on antibiotic therapy and reinitiating of DMARDs prompted seeking an alternative/concurrent diagnosis. The work-up yielded a pulmonary embolism (PE) on the background of having no other risk factors for thrombosis. CONCLUSIONS In the reviewed literature, there is a close association between hyperferritinemia and AoSD complicated with venous thromboemboli (VTEs). A rigorous search for alternative diagnoses as well as other potential uncommon complications of AoSD is needed when working-up patients with AoSD, especially those that are not getting better on therapy. Given the rarity of AoSD, meticulous data collection may be useful in understanding the pathophysiology and features of presentation of the illness, including complications such as VTEs.