Concurrency of systemic sclerosis and sarcoidosis: a case-based review

Systemic sclerosis (SSc) and sarcoidosis are two rare, multisystem autoimmune diseases with distinct pathophysiologic mechanisms and clinical features. Their coexistence is uncommon and remains an ongoing research subject to determine its significance and underlying mechanisms. Herein, we report the case of a 58-year-old woman with Raynaud's phenomenon, sclerodactyly, and anti-Scl-70 positive, who was initially diagnosed with SSc. Twelve months into treatment, she developed weight loss, fatigue, and progressive respiratory impairment. Imaging revealed mediastinal and mesenteric lymphadenopathy along with fibroatelectatic lung changes. Endobronchial ultrasound-guided biopsy and PET-CT scan suggested sarcoidosis, which was histologically confirmed by the presence of noncaseating granulomas and multinucleated giant cells. The patient was diagnosed with an overlap syndrome of SSc and sarcoidosis and treated accordingly. Clinical improvement and radiologic regression of lymphadenopathy were observed 2 months post-treatment. This is one of the few published cases of concurrent SSc and scleroderma. A review was also performed on the known cases, emphasizing possible pathophysiologic mechanisms, clinical and laboratory findings that can contribute to an early and accurate diagnosis. According to the known evidence, 68.9% of reported cases involve female patients, and in approximately half of them, SSc was diagnosed first. In particular, limited SSc appears to be nearly twice as prevalent as the diffuse form. Our literature review underscores the rarity of this overlap and highlights recurring patterns that may aid in clinical recognition. However, the limited number of reported cases highlights the need for further studies to better define the epidemiology, pathogenesis, and optimal management of this uncommon association.