CPC06 Darier–Roussy disease (subcutaneous sarcoidosis): a rare presentation of cutaneous nodules in pulmonary sarcoidosis

Abstract Darier–Roussy disease, or subcutaneous sarcoidosis, is a rare cutaneous manifestation of sarcoidosis first described in 1904 by French dermatologist Ferdinand-Jean Darier and Swiss–French pathologist Gustave Roussy. Subcutaneous sarcoidosis accounts for approximately 1–4% of cases of sarcoidosis, although some studies suggest a higher prevalence, ranging from 4.3% to 12.1%. This case report describes a 37-year-old Eritrean man with a known history of pulmonary sarcoidosis who presented with subcutaneous nodules. He reported an 18-month history of firm, violaceous, mildly tender nodules on his upper arms, initially thought to resemble panniculitis or cutaneous sarcoidosis, alongside right-wrist and left-foot lipoma. The patient denied systemic symptoms such as gastrointestinal disturbances, fever or weight loss but reported fatigue, occasional shortness of breath, and chest pain on deep inspiration. Clinical examination revealed that he was haemodynamically stable, with no significant findings on respiratory, cardiovascular or gastrointestinal assessments. Diagnostic investigations included a negative autoimmune and blood-borne virus screen. Biopsy of a left-upper-arm nodule revealed transdermal histiocytic granulomas with Langerhans-type giant cells and occasional central necrosis, surrounded by a thin rim of lymphocytes. Special stains, including periodic acid–Schiff and Ziehl–Neelsen, showed no fungi or acid-fast bacilli. These findings confirmed a diagnosis of granulomatous dermatitis consistent with cutaneous sarcoidosis. Treatment involved a weaning course of oral prednisolone combined with topical clobetasol propionate, resulting in significant symptom improvement. This case is notable as subcutaneous nodules are a rare manifestation of sarcoidosis. Documenting such presentations enhances understanding of this uncommon condition and aids in distinguishing it from other differential diagnoses, such as panniculitis or lipomas.