Granuloma annulare

Granuloma annulare is a chronic skin disease consisting of a rash with reddish bumps arranged in a circle or ring. It most often affects children, young and older adults and it is slightly more common in females (60/40 ratio). The condition is usually seen in otherwise healthy people. Occasionally, it may be associated with diabetes or thyroid disease. Its cause is unknown.

Presentation
Granuloma annulare is usually asymptomatic, but the rash may burn and be itchy. Patients usually notice a ring of small, firm bumps (papules) over the backs of the forearms, hands or feet, often centered around joints or knuckles. The bumps are caused by the clustering of T cells below the skin. Occasionally, multiple rings may be found. Rarely, granuloma annulare may appear as a firm nodule under the skin of the arms or legs.

Prognosis
Because granuloma annulare is usually asymptomatic, treatment may not be necessary except for cosmetic reasons. Most lesions of granuloma annulare disappear in pre-puberity patients with no treatment within two years while older patients (50+) have rings for upwards of 20 years. The appearance of new rings years later is not uncommon.