Photo-distributed Generalized Granuloma Annulare: An Exceedingly Rare Presentation of a Chronic Debilitating Dermatosis

Summary: Generalized granuloma annulare (GGA) is an idiopathic dermatosis accounting for 10% of all granuloma annulare variants. We herein describe a case of photo-distributed GGA, an especially rare subtype with only a few documented in literature. A 60-year-old White man presented with a 2-month history of pruritic red eruption on the upper body, developed after prolonged outdoor exposure. Examination noted diffuse erythematous papules and annular plaques across the neck, upper back, and distal upper extremities. Biopsy microscopy revealed dermal interstitial histiocytic infiltrates, multinucleated giant cells, and bundles of altered collagen. All relevant labs, stains (e.g., GMS, Gram, and AFB), and immune panels were negative and a diagnosis of GGA was rendered. Limited to literature-based guidelines, 2-month treatment with hydroxychloroquine, tacrolimus, and triamcinolone demonstrated no improvement and symptoms persisted despite a recent 1-month trial of rifampin, ofloxacin, and minocycline. The photo-distributed GGA subtype reportedly has a chronic, recurrent, and treatment-resistant course, resulting in extensive scarring and disfigurement in sun-exposed skin. Hence, effective management to minimize debilitating outcomes relies on timely diagnosis and intervention, though impeded by disease’s rarity and numerous clinical differentials for photo-distributed dermatoses. Clinicians and pathologists should be familiar with the potential of GGA to arise in a photo-distributed manner.