DermDx: Crusty Nodule on Leg

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A 55-year-old man is referred for evaluation of a lesion on his leg, which he first noted approximately 2 months prior to this visit. One year ago, he developed a rash on his hands that was diagnosed as granuloma annulare. This condition has persisted despite topical therapy with clobetasol cream. He currently takes oral medications for both arthritis and adult-onset diabetes. Physical examination reveals classic granuloma annulare of his hands as well as an erythematous, firm plaque of the upper right anterior tibial area containing 2 crusted papules.

Biopsy of the lesion revealed perforating granuloma annulare (PGA). This condition is an uncommon variant of granuloma annulare; other subtypes include disseminated and subcutaneous forms.1 Granuloma annulare is a benign skin reaction that may involve the T-helper 1 (Th1) axis...

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Biopsy of the lesion revealed perforating granuloma annulare (PGA). This condition is an uncommon variant of granuloma annulare; other subtypes include disseminated and subcutaneous forms.1 Granuloma annulare is a benign skin reaction that may involve the T-helper 1 (Th1) axis as well as dysregulation of the Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway.2 Most cases of granuloma annulare arise spontaneously, although localized trauma or infection have been correlated with onset. Affected individuals have a higher incidence of diabetes and hyperlipidemia and these may be risk factors for the development of granuloma annulare.3

Perforating granuloma annulare most commonly manifests as umbilicated papules or pustules accompanied by scales or crust.4 A case of generalized lesions was recently reported as well as a case that resembled psoriasis.5,6 The condition is distinguished histopathologically by the appearance of necrotic material that perforates the epidermis and by the presence of granulomas within the dermis.7

A variety of treatment options have been reported including excision and intralesional injections of triamcinolone. In one study comparing treatments, most patients experienced spontaneous resolution of perforating granuloma annulare.6,7

Stephen Schleicher, MD, is director of the DermDox Dermatology Centers, associate professor of medicine at Geisinger Commonwealth Medical College, and clinical instructor of dermatology at Arcadia University and Kings College.

References

1. Oakley A. Granuloma annulare. DermNet. Accessed January 4, 2023. https://dermnetnz.org/topics/granuloma-annulare

2. Joshi TP, Duvic M. Granuloma annulare: an updated review of epidemiology, pathogenesis, and treatment options. Am J Clin Dermatol. 2022;23(1):37-50. doi:10.1007/s40257-021-00636-1

3. Barbieri JS, Rosenbach M, Rodriguez O, Margolis DJ. Association of granuloma annulare with type 2 diabetes, hyperlipidemia, autoimmune disorders, and hematologic malignant neoplasms. JAMA Dermatol. 2021;157(7):817-823. doi:10.1001/jamadermatol.2021.1805

4. Pap N, Bradamante M, Ljubojević HS. Localized perforating granuloma annulare. Acta Dermatovenerol Croat. 2019;27(1):33-36.

5. Salzmann M, Rendon A, Toberer F, Hassel JC. Generalized perforating granuloma annulare: a case report. J Dtsch Dermatol Ges. 2021;19(4):585-587. doi:10.1111/ddg.14442

6. Jacob JS, Krenek G, Tschen J. Perforating granuloma annulare mimicking psoriasis. Cureus. 2020;12(8):e9983. doi:10.7759/cureus.9983

7. Penas PF, Jones-Caballero M, Fraga J, Sánchez-Pérez J, García-Díez A. Perforating granuloma annulare. Int J Dermatol. 1997;36:340-348. doi:10.1046/j.1365-4362.1997.00047.x

This article originally appeared on Clinical Advisor