May 2006

This 12-year-old girl has a five-month history of a non-tender skin-colored movable nodule of the anterior lower right leg. In addition, a new lesion was noted three weeks ago on her right arm, which is shown in the photograph. She is otherwise asymptomatic. She has been treated for two weeks with an antifungal cream from her primary care physician without any change in the lesion. She lives with her parents in the city, they have one dog. What is your diagnosis?

Answer

This child has granuloma annulare.

Typically, this condition presents as a nodular circular or annular lesion that is asymptomatic. Granuloma annulare is most common in children and young adults. This condition is also more common in girls. The lesions occur most often in areas susceptible to minor trauma, for example, ankles, dorsal feet, and wrists. They can, however appear on any part of the body. Multiple lesions may be present. However, about 50% of patients will have only a single lesion. Subcutaneous granuloma annulare is noted often on the anterior part of the lower leg. Other locations include scalp, buttocks, fingers and eyelids. The nodules have normal overlying epidermis.

A more rare form of granuloma annulare, the generalized form, is primarily seen in adults. Studies in adults have shown some association with diabetes mellitus; however, this association has not been fully documented in children.

A biopsy of a superficial granuloma annulare lesion shows focal degeneration of collagen. The areas of degeneration can be surrounded by palisading histiocytes, lymphocytes and fibroblasts (palisading granuloma). A biopsy of a subcutaneous nodule is read as a pseudorheumatoid nodule, but in fact it has no connection with a diagnosis of rheumatoid arthritis.

The differential diagnoses for superficial granuloma annulare can include tinea corporis (has less nodularity and scale, sometimes itching) and erythema migrans (has tick exposure and symptoms of Lyme disease).

The differential diagnoses for subcutaneous granuloma annulare can include rheumatoid nodule (usually over tendons), pilomatrixoma (an irregular shape), bony tubercle (non-movable), sarcoidosis (other systemic symptoms) rhabdomyosarcoma (typically deep seated and non-movable).

Treatment

This condition generally resolves without therapy after three to four years. Most often, watchful observation is recommended. Case reports have indicated successful treatment with topical corticosteroids, oral corticosteroids, topical immunomodulators, dapsone, oral retinoids, cyclosporin and etanercept among others.

For more information:

• Fairlie C. Granuloma annulare. Dermatol Nurse. 2004;16:526.
• Hutcheson AC, Hurray DH, Smith MT, et al. Subcutaneous granuloma annulare of the scalp: a case report and case review. Cutis. 2005;76:377-382.
• McNeal S, Daw JL Jr. Subcutaneous granuloma annulare: an unusual presentation in the eyelids and scalp. Ann Plast Surg. 2005;55:684-686.