Dermatophyte Tinea Infection of the Skin

Description

Along the right anterolateral male torso, the proximal upper arm is shown with a single, well-demarcated annular erythematous plaque on the skin surface, centered over the lateral aspect of the brachium. The lesion expands centrifugally with relative central clearing and a more inflamed peripheral margin, consistent with a superficial dermatophyte tinea corporis pattern in the keratinized epidermis. Superior and medial to the lesion, the pectoral region and nipple are visible as stable landmarks, helping orient the viewer to trunk versus limb. Annular “ringworm” lesions on the arm are a common presentation of dermatophytosis acquired through direct contact, fomites, or autoinoculation from tinea pedis. Edge activity matters: clinicians often sample the leading border for potassium hydroxide preparation or fungal culture, and mistaking dermatophyte mycosis for eczema can lead to topical corticosteroid use and tinea incognito with less obvious scaling but persistent spread. The upper arm location also helps teach distribution, single versus multiple plaques, and how lesion morphology guides the differential with nummular dermatitis, granuloma annulare, pityriasis rosea, or erythema migrans. Dermatology and infectious disease courses can use this image to reinforce classic tinea corporis morphology and lesion mapping on the trunk and proximal limb, while publishers can pair it with text on bedside diagnosis, KOH technique, and first-line topical antifungals (for example, terbinafine or azoles). Primary care and occupational health teams will also find it useful for patient education on contagion, hygiene, and when to evaluate household contacts or pets. Anatomical accuracy verified by SciePro's Medical Advisory Board.