Abstract

Granuloma annulare (GA) is a benign inflammatory dermatosis recognized clinically by annular erythematous lesions and identified histologically by granulomatous inflammation with mucin. It is commonly associated with diabetes and hyperlipidemia. Becker's nevus (BN) is a benign, acquired, sharply demarcated, hyperpigmented, unilateral patch often with hypertrichosis. These two entities commonly have little to no association, which is why the following case is so unique. We present a case of a 58-year-old man with a history of BN plaque on his left upper chest and neck who came to the clinic for an itchy rash. The rash is localized to his left upper chest and neck, in the same distribution as his BN, and has been present for 4-5 years. He was seen for this same rash two years prior and was diagnosed with eczema. Triamcinolone cream was prescribed, which helped initially, but the rash returned and no longer responded to the steroid. A punch biopsy of the lesion was performed and sent to pathology. Acanthosis, basal hyperpigmentation, and rete-ridge elongation were identified, consistent with BN. However, underlying the BN was granulomatous inflammation and mucin within the interstitium, diagnostic of granuloma annulare. CD68 was performed and highlighted the small interstitial histocytes. GA classically has 2 patterns: palisading and interstitial. Our case fits the interstitial pattern since the histiocytic inflammation is dispersed through the interstitium and lacks any necrobiosis. Inflammatory dermatoses, such as lichen planus, have been reported with BN but very rarely has a case of GA arising from BN been reported.