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A 2.5-year-old girl with an annular plaque
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A 2.5-year-old girl presented to the clinic complaining of a skin colored annular plaque on her right arm.
Her mother reported it had been present for a few weeks and was asymptomatic. Her mother did not recall any trauma or prior insect bite to the area. The patient has otherwise been healthy. Her mother initially thought it was ringworm due to its annular nature and treated it with an over-the-counter antifungal cream with no improvement. In fact, the lesion has spread centrifugally, and the border became increasingly elevated.
What is your diagnosis?
Answer
The answer is granuloma annulare.
GA is a common inflammatory cutaneous disorder that is often seen in children and young adults. The etiology is unknown, but several triggers have been implicated, including a prior history of trauma at the site of the lesion, insect bites, sun exposure, viral and bacterial infections, as well as vaccinations. It has also been associated with diabetes mellitus, primarily type I, and thyroid disease, although most patients with GA are healthy. The pathogenesis of GA involves alteration of connective tissue in the dermis surrounded by granulomatous inflammation.
There are many types of GA. The most common type is localized and consists of lesions that are skin-colored, pink, red, or violaceous especially on the legs, are more prevalent on the dorsal surfaces of the extremities, and form a ring with central clearing. Lesions of GA often start as small papules that expand into full or partial annular plaques. They range in size from 5 millimeters (mm) to 5 centimeters (cm). The border may consist of a single discrete peripheral ridge or many small dermal papules coalescing to give a beaded appearance. There is no scale, and there are no pustules. Patients are usually asymptomatic but may complain of mild pruritus. Children also may develop the subcutaneous type of GA that consists of 6 mm to 3.5 cm rapidly growing, firm, asymptomatic nodules often localized to the anterior pretibial region, hands, feet, fingers or scalp. These lesions may be solitary or multiple. Other types of GA seen less often in children include generalized, perforating, and patch variants.
The diagnosis is usually made clinically. In atypical cases, biopsy may be helpful. Histologic examination reveals granulomas composed of degenerative collagen with mucin deposition centrally and a palisading lymphohistiocytic infiltrate peripherally. The granulomas are located in the superficial and middle dermis although the deep dermis and subcutaneous fat may also be involved.
The differential diagnosis of the localized annular type includes tinea corporis, annular lichen planus, erythema chronicum migrans, subacute cutaneous lupus erythematosus, and an acute febrile neutrophilic dermatosis such as Sweet syndrome. Infections such as atypical mycobacteria, tuberculosis, and syphilis should be ruled out. In the subcutaneous type, consider erythema nodosum, rheumatoid nodules, deep infections, tumors, malignancy or a dermoid cyst. Biopsy may be needed for definitive diagnosis of deep GA in the absence of more typical superficial lesions.
Lesions typically last many months to years and resolve on their own without sequelae. Therefore, reassurance and patience is the best treatment option. There are many reports of anecdotal therapies including moderate potency topical steroids under occlusion, intralesional steroid injections, tacrolimus ointment, pimecrolimus cream, imiquimod, and cryotherapy. Skin biopsy has been reported to induce regression. Systemic therapies are rarely used in children but include corticosteroids, cyclosporine, dapsone, isotretinoin, antimalarial drugs, photochemotherapy, and biologic agents. It is important to be aware of the clinical features of GA to prevent misdiagnosis and unnecessary treatment.
For more information:
- Marissa J. Perman, MD, is a PL-III resident at Cincinnati Children’s Hospital Medical Center.
- Barron DF, Cootauco MH, Cohen BA. Granuloma annulare. A clinical review. Lippincotts Prim Care Pract. 1997 Mar-Apr;1(1):33-9.
- Cyr PR. Diagnosis and management of granuloma annulare. Am Fam Physician. 2006 Nov 15;74(10):1729-34.
- Prendiville JS. Granuloma Annulare. In: Wolff K, Goldsmith LA, Katz SI, Gilchrest BA, Paller AS, Leffell DJ, eds. Fitzpatrick’s Dermatology in General Medicine. 7th Ed. New York, NY. McGraw-Hill, 2008. 369-373.
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