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A 4-year-old girl is referred for evaluation of a lesion on her foot that her parents noticed approximately 6 weeks ago. The patient is not bothered by the lesion and does not have similar marks elsewhere on her body. She is of normal weight, height, and mentation for her age. Triamcinolone cream was initially prescribed but was ineffective. Examination reveals a well-demarcated, firm, erythematous nodule on the dorsal lateral surface of her left foot. Palpation does not elicit tenderness.
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The patient underwent punch biopsy that revealed granuloma annulare (GA), an idiopathic skin disorder characterized by annular, flesh-colored to erythematous papules and plaques that commonly appear on the dorsal surfaces of the hands and feet. Histology may reveal granulomatous inflammation, degeneration of collagen, and mucin deposition.1
Biopsy revealed an interstitial pattern with a paucity of granulomatous features.1 Interstitial GA has been associated with interferon therapy and borreliosis.2,3
Clinically, this patient’s lesion is classic for subcutaneous GA, which presents as an erythematous, firm nodule. Subcutaneous GA is seen almost exclusively in children, with presentation primarily on the lower extremities and buttocks.4
Immune activation of fibroblasts may play a role in the pathogenesis of GA.4 A variety of therapies have proven effective for localized GA; however, there is no gold standard of treatment as most reports involve few patients with the condition.5 The majority of lesions will spontaneously resolve within 2 years of onset.
Greg Forsyth, PA-C, is a physician assistant at the DermDox Center for Dermatology in Mechanicsburg, Pennsylvania, and Stephen Schleicher, MD, is director of the DermDox Center for Dermatology, as well as an associate professor of medicine at Commonwealth Medical College and a clinical instructor of dermatology at Arcadia University and Kings College.
References
1. Ronen S, Rothschild M, Suster S. The interstitial variant of granuloma annulare: clinicopathologic study of 69 cases with a comparison with conventional granuloma annulare. J Cutan Pathol. 2019;46(7):471‐478.
2. Kluger N, Moguelet P, Chaslin-Ferbus D, Khosrotherani K, Aractingi S. Generalized interstitial granuloma annulare induced by pegylated interferon-alpha. Dermatology. 2006;213(3):248-249.
3. Gualco F, Zaccaria E, Drago F, Rebora A. Interstitial granuloma annulare and borreliosis: a new case. J Eur Acad Dermatol Venereol. 2007;21(8):1117-1118.
4. Piette EW, Rosenbach M. Granuloma annulare: clinical and histologic variants, epidemiology, and genetics. J Am Acad Dermatol. 2016;75(3):457-465.
5. Wang J, Khachemoune A. Granuloma annulare: a focused review of therapeutic options. Am J Clin Dermatol. 2018;19(3):333-344.
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