Granuloma Annulare

Key Points
Relatively common skin condition, generally occurring in children, teenagers and young adults
Cause is not entirely known, but probably represents a reaction pattern to various immune stimuli
Consists of several subtypes, which present differing symptoms

Granuloma annulare is an relatively common skin condition. Consisting of three subtypes (localized, generalized, and deep) with different symptomatic presentations, it may occur anywhere on the body. It presents only on the skin and is not harmful. Some affected persons may not even develop symptoms, but the most common is tenderness of the affected area.

Localized granuloma annulare consists of red, pink, or flesh colored bumps commonly over joints. They will sometimes form in rings. Rings may be slightly depressed centrally. It is most common on the hands, but may also occur on the feet, ankles and elbows. Generalized granuloma annulare consists of widespread pink, mauve, or skin colored papules, forming in large rings. They often occur around folds of the skin, and the condition may be associated with other diseases, usually diabetes mellitus. Deep granuloma annulare most commonly forms along the scalp line, tips of the fingers, and on the shins, and consist of rubbery nodules resembling the nodules which form due to rheumatoid arthritis.

The cause of granuloma annulare is unknown, but it most likely represents a reaction pattern with many different initiating factors. It has been hypothesized to be associated with numerous infections such as Tinea (ringworm), Tuberculosis, HIV, Epstein-Barr virus, hepatitis B virus, hepatitis C virus, and Herpes Zoster virus. Other reported causes include insect bites, trauma, sun exposure, thyroiditis, and vaccinations. However, these suggested etiologic factors remain unproven.

Differential Diagnosis (Other conditions with similar appearance)
Erythema Annulare Centrifugum
Erythema Elevatum Diutinum
Lichen Planus

Localized
Annular Lichen planus
Acute febrile neutrophilic dermatosis
Fat necrosis
Hansen disease
Mucocutaneous paraneoplastic syndrome
Necrobiosis lipoidica diabeticorum
Tinea corporis

Generalized
Cutaneous metastases
Cutaneous paraneoplastic syndrome
Lichen myxedematous
Lichen planus
Sarcoidosis

Deep
Dermoid cyst
Erythema nodosum
Rheumatoid nodule

Diagnosis
Key Points
Diagnosis based on appearance of the affected area
Skin Biopsy will be performed to confirm diagnosis

Diagnosis of Granuloma annulare is very often based on the appearance of the affected area, as symptoms are characteristic. A skin Biopsy of the affected area will be performed to confirm the diagnosis.

Treatment
Most cases do not require treatment, and will resolve spontaneously
Several treatment options exist
In cases which are widespread, further treatment may be attempted, with varying degrees of effectiveness

Granuloma annulare is not harmful and will often resolve spontaneously in several months in mild cases, though in other cases it may last years. However, if treatment is prescribed it will often come in the form of strong topical or injected steroids on the affected area. In a small number of cases, topical Imiquimod or calcineurin inhibitors such as tacrolimus and pimecrolimus have been used.

In more severe and widespread cases, systemic treatment may be utilized, including systemic steroids, isotretinoin, methotrexate, potassium iodide, dapsone, pentoxifylline, antibiotic combinations, phototherapy, photodynamic therapy, cyclosporine, and biological response mediators. It should be noted that even in cases where treatment is effective, the condition will often recur once treatment is discontinued.