Editor's note: This case is reprinted from the "Spot the Rash" department of Infectious Diseases in Children, a sister SLACK Incorporated publication.
A 12-year-old girl presents with a 5-month history of a nontender, skin-colored, movable nodule on the anterior lower right leg. In addition, a new lesion was noted 3 weeks ago on her right arm (see image above). She is otherwise asymptomatic.
She has been treated for 2 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.
Typically, granuloma annidare presents as a nodular circular or annular lesion that is asymptomatic. Granuloma annulare is most common in children and young adults and is more common in girls. The lesions occur most often in areas susceptible to minor trauma, such as the 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 often are noted on the anterior part of the lower leg (Figure). Other common locations include scalp, buttocks, fingers, and eyelids. The nodules have normal overlying epidermis.
A more rare form of granuloma annulare, the generalized form, is seen primarily in adults. Studies in adults have shown some association with diabetes, but 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, has no connection with a diagnosis of rheumatoid arthritis.
The differential diagnoses for superficial granuloma annulare can include tinea corporis, which has less nodularity and scale and sometimes itching, and erythema migrans, which is seen with tick exposure and symptoms of Lyme disease. The differential diagnoses for subcutaneous granuloma annulare can include rheumatoid nodule (usually over tendons), pilomatrixoma (has an irregular shape), bony tubercle (nonmovable), sarcoidosis (other systemic symptoms), or rhabdomyosarcoma (typically deepseated and nonmovable).
This condition generally resolves without therapy after 3 to 4 years. Most often, watchful observation is recommended. Case reports have indicated successful treatment with topical corticosteroids, oral corticosteroids, topical immunomodulators, dapsone, oral retinoids, cyclosporine, and etanercept, among others.
Figure. As shown in another patient, subcutaneous granuloma annulare may be seen on the anterior part of the lower leg.