Diagnosis: Granuloma annulare
Long-standing disseminated granuloma annulare on the left or right leg.. Clinical photograph sourced from Wikimedia Commons (CC BY-SA 2.0). Attribution: Kreuter et al Uploaded by My Core Competency is Competency at en.wikipedia.
Localized (most common): flesh-colored to erythematous, annular plaques with raised borders and central clearing on dorsal hands/feet. Generalized: widespread papules, often truncal. Subcutaneous: firm nodules in children, often pretibial.
Often asymptomatic and incidentally discovered. May follow trauma or insect bites. Localized form is usually self-limited (resolving within 2 years in 50%). Generalized form may be associated with diabetes, dyslipidemia, thyroid disease.
Localized: often observation (self-limited). Potent topical/intralesional corticosteroids. Cryotherapy. Generalized: phototherapy (NB-UVB, PUVA), dapsone, hydroxychloroquine, biologics (dupilumab, JAK inhibitors in refractory cases).
Tinea corporis, Annular lichen planus, Necrobiosis lipoidica, Sarcoidosis, Erythema annulare centrifugum, Morphea
KOH preparation helps exclude tinea corporis. GA lacks scale (unlike tinea — 'the ringworm that doesn't scale'). Palisading granulomas with mucin deposition on histopathology are characteristic. Screen for diabetes in generalized GA.
Tags: granuloma annulare, granulomatous, benign, annular