Background: Adult-onset Still's disease (ASD) is an uncommon clinical entity. It is a diagnosis of exclusion, characterized by a clinical triad of intermittent fever spikes, evanescent rash, and either arthralgia or arthritis. Destructive arthritis more commonly affects the hips, wrists, tarsal joints and cervical spine.
Aim: To report an unusual case of ASD with severe distal interphalangeal destructive arthritis and finger skin vesiculopustules.
Observation: A 19 years old girl was followed for 2 year-history of ASD with polycyclic articular involvement. She noted, since 2 months, rapid appearance of painful tumefaction in the distal interphalangeal joints (DIP) with maculopustular eruption distributed exclusively on the hands, in front, only of DIP and few proximal interphalangeal joints (PIP). Further more, she complained of polyarticular active disease. Hands and wrists X-ray showed narrowed distal-interphalangeal joint space of only DIP joints. RMN imaging revealed in addition carpal, metacarpal and PIP articular inflammatory damage. The infectious investigation remained negative. A surgical skin and DIP biopsy specimens showed disseminated micro-abscesses with polynuclear leukocyte dermal infiltration. There was no signs of osteitis. Bacterial and fungal cultures from the pus failed to reveal any causative organisms. Skin lesions gradually disappeared in response to conventional ASD therapy after intensification. Hence, the diagnosis of distal destructive arthritis of ASD associated with atypical neutrophilic dermatosis (Sweet's syndrome) was made.
Conclusion: ASD is rare, heterogeneous, with unpredictable evolution. The distal destructive arthritis represents a possible complication. The presence of pustules as atypical cutaneous features of Sweet's syndrome may be seen in severe forms of ASD and clinicians must be alert to the possibility of a misdiagnosis in these cases.