Abstract
A 65-year-old woman presented with numerous erythematous lesions on her eyelids, persisting for five months despite treatment with fexofenadine hydrochloride and topical corticosteroids. Her medical history included diabetes mellitus and dyslipidemia, managed with rosuvastatin, metformin, and a combination of teneligliptin and canagliflozin. Rosuvastatin was discontinued due to suspected interstitial granulomatous dermatitis; however, the lesions remained unchanged. Clinical examination revealed annular plaques predominantly on sun-exposed areas. A skin biopsy demonstrated non-caseating granulomas with eosinophilic infiltration. Elevated levels of serum angiotensin-converting enzyme (ACE), calcium, and soluble interleukin-2 receptor supported a diagnosis of cutaneous sarcoidosis. The lesions were refractory to systemic and topical corticosteroid treatments, raising the possibility of photosensitivity. Phototesting revealed UVB sensitivity during metformin use, which resolved following discontinuation of the drug. The patient's lesions improved within one week of stopping metformin, allowing for successful prednisone tapering without recurrence. This case underscores metformin as a potential photosensitizing agent in cutaneous sarcoidosis. Although the relationship between diabetes mellitus and sarcoidosis remains unclear, chronic inflammation associated with diabetes may contribute to the progression of sarcoidosis. In cases of refractory cutaneous sarcoidosis unresponsive to systemic corticosteroid treatment, the possibility of photosensitivity, particularly drug-induced photosensitivity, should be considered. A thorough review of the patient's medication history is therefore critical for accurate diagnosis and effective management.