The latest in GP and hospital practitioner Dr Andy Jordan's series on differentiating two often similar-looking skin conditions
Both granuloma annulare and tinea corporis conditions may have a circular appearance with a raised edge, but their aetiology and treatment are very different.
Granuloma annulare
• Usually occurs before middle age
• Twice as common in women as in men
• Presents as a papule which gradually expands to form a ring of red or flesh-coloured papules, like cobblestones – you can stretch the skin to see this better
• No scale – due to dermal pathology
• Tends to enlarge centrifugally
• May be solitary or multiple
• Can appear anywhere, but usually on back of hands, feet, ankles or the overlying bony promontories of fingers
• Painless, but may be itchy – especially during the expanding phase
• Possible – but unusual – association with diabetes, so it's worth testing urine
• Tends to remit spontaneously, but if itchy topical steroids may be used sparingly
• Intralesional steroids and cryotherapy are effective for localised lesions.
Tinea corporis
• Can occur at any age
• Is an infection of hair-free skin caused by any of the dermatophytes
• Equal incidence in both sexes
• Very characteristic lesions – usually circular with a raised erythematous active, scaly edge
• Lesions may be single or multiple
• Often central resolution of inflammation, but there may be post-inflammatory pigmentation in the centre of the lesion
• Size of the lesion gradually increases
• Lesions may be anywhere on the body
• Pustules may be present in the lesion if the dermatophyte is of animal origin
• Infection may have arisen in the web spaces of the toes, so check the feet
• Runs a chronic indolent course without treatment
• Topical imidazole or topical terbinafine may be all that is needed, but oral terbinafine might be necessary
• If topical steroids have been used inappropriately on the lesion, then the scale may not be evident (tinea incognito)
• Have a low threshold for taking skin scrapings.
Dr Andy Jordan is a GP and hospital practitioner in dermatology in Chesham, Buckinghamshire
Tinea corporis Tinea corporis Granuloma annulare Granuloma annulare