by Kristy Fleming, MD
A 31-year-old Latino man with diabetes presents to the dermatology clinic with pruritic plaques on the base of the neck and bilateral lateral trunk. The plaques appeared approximately three months earlier and have since increased in size and number. The lesions had no scale and were slightly indurated to palpation. The patient reported no new medications or topical agents. He has never had any type of skin disease in the past and none of his close contacts have similar lesions. What’s your diagnosis?Submit your answer and read the full explanation below. If you like this activity or have a suggestion, tell us about it in the comment box at the bottom of the page.
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Granuloma annulare (GA) is a relatively common idiopathic skin disorder. There are many theories attempting to elucidate the etiology of GA. These include reaction to trauma, insect bite, viral infection and ultraviolet light exposure, but no clear association has been identified.
The link between GA and diabetes remains controversial – some studies support the association; others refute it.1,2 Patients may present at any age, however two-thirds of patients are younger than 30 years and the female-to-male ratio is 2:1.3
GA may have several different morphologies, but classically presents as annular or arciform dermal plaques without scale. Lesions tend to favor acral sites but may appear on other areas as well.
Approximately 60% of GA lesions are isolated to the hands and arms, 20% to the feet and legs, 7% involve both the upper and lower extremities and 5 to 10% involve the trunk.4
A generalized GA variant presents with extensive lesions that may number in the hundreds. This variant has a poor response to therapy and is more common in patients with HIV.
Lesions are benign, asymptomatic to mildly pruritic and resolve spontaneously. GA resolution can occur in a few weeks or several decades, but 50% resolve within two years.4 Clinicians should advise patients that there is about a 40% chance that GA lesions will recur and that treatment does not decrease this risk.
There is no specific test for GA. Diagnosis is based on clinical and histopathologic features. It is important to rule out more serious disorders that may be clinically similar such as borderline leprosy, annular mycosis fungoides, syphilis and sarcoidosis.
Clinicians can perform skin biopsy to confirm GA diagnosis. GA is a granulomatous dermatitis with mucin deposition. It may have one of three histologic patterns: interstitial, palisading granulomatous or sarcoidal (epitheloid histiocytic nodules).4 The mucin is a sensitive marker and can be highlighted using special stains, such as colloidal iron or Alcian blue.
Given the benign nature of GA and eventual spontaneous resolution, no therapy is required.
For patients with cosmetic concerns and limited disease clinicians may prescribe high-potency topical corticosteroids or intralesional injection with triamcinolone suspension. Other treatment options include photochemotherapy with psoralen and ultraviolet A (PUVA), cryosurgery or carbon dioxide laser.
Treatments for systemic GA are numerous, though none have been proven universally effective, and lesions often recur after therapy is discontinued.
GA symptom improvement has also been reported with niacinamide, isotretinoin, antimalarials, dapsone, pentoxifylline, cyclosporine, chlorambucil, etretinate, etanercept, and infliximab.4
A study performed in 2009 found combination triple antibiotic therapy with ofloxacin 400 mg, rifampin 600 mg, and minocycline hydrochloride 100mg given monthly resulted in resolution of clinical lesions within three months.5 This regimen may be an option for cases resistant to standard treatment modalities.
2. Studer EM, Calza AM, Saurat JH. Precipitating factors and associated diseases in 84 patients with granuloma annulare: a retrospective study. Dermatology. 1996;193:364-8.
3. J Bolognia, JL Jorizzo, RP Rapini. Dermatology 2nd Ed. Elsevier; 2008:1426-1429.
4. James WD, Berger TG, Elston DM. Andrew’s Diseases of the Skin Clinical Dermatology. 10th ed. Pennsylvania: Saunders Elsevier; 2006: 703-705.
5. Marcus DV, Mahmoud BH, Hamzavi IH. Granuloma Annulare Treated With Rifampin, Ofloxacin, and Minocycline Combination Therapy. Arch Dermatol. 2009;145(7):787-789.