Granuloma annulare — Viva

Q1: Definition and histology (2 min)

What is granuloma annulare? What is the characteristic histological finding, and what stain can be used to demonstrate it?

^[1][10]Model answer: Granuloma annulare is a benign, usually self-limiting granulomatous dermatosis characterized histologically by palisading granulomas — a central focus of necrobiotic collagen and mucin surrounded by palisading histiocytes. Mucin is an acid mucopolysaccharide and can be demonstrated with Alcian blue, colloidal iron or toluidine blue stains.

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Q2: Clinical variants (3 min)

What are the main clinical variants of granuloma annulare? How does localized GA differ from generalized GA in terms of distribution, age and prognosis?

^[2][8]Model answer: The main variants are localized, generalized/disseminated, subcutaneous (deep), perforating and patch-type. Localized GA is the commonest (~70–75%), occurs in children and young adults, affects the dorsa of hands and feet, and is usually self-limiting. Generalized GA occurs in adults, presents with widespread papules and plaques on the trunk and extremities, is more persistent and refractory, and is associated with systemic diseases such as diabetes, dyslipidaemia and thyroid disease.

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Q3: Differential diagnosis (3 min)

A patient has an annular lesion on the hand. How would you distinguish granuloma annulare from tinea corporis, necrobiosis lipoidica and rheumatoid nodule?

^[3][6]Model answer:

• Tinea corporis: has a scaly, raised advancing edge, is usually pruritic and KOH microscopy shows hyphae. GA has a smooth, non-scaly surface.
• Necrobiosis lipoidica: occurs on the shins, with yellow-brown atrophic shiny plaques, telangiectasia and strong diabetes association; histology shows layered horizontal granulomas across the entire dermis without mucin.
• Rheumatoid nodule: occurs over joints in patients with rheumatoid arthritis, is RF positive and shows palisading granulomas with fibrinoid necrosis, not mucin.

Q4: Investigations (2 min)

What investigations would you arrange in a patient with generalized granuloma annulare?

^[3][5]Model answer: In generalized GA I would screen for associated systemic disease: fasting plasma glucose and HbA1c for diabetes, lipid profile for dyslipidaemia, TSH and free T4 for thyroid disease, and HIV testing if risk factors. In older patients or those with systemic symptoms, I would consider age-appropriate malignancy screening. A skin biopsy is useful if the diagnosis is uncertain.

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Q5: Management (3 min)

How would you manage a patient with localized granuloma annulare? What options are available for generalized or refractory disease?

^[2][3]Model answer: For localized GA, observation and reassurance is first-line because most cases resolve spontaneously. If treatment is needed, I would use potent topical corticosteroids (clobetasol propionate 0.05% under occlusion) or intralesional triamcinolone acetonide 2.5–5 mg/mL. Alternatives include cryotherapy, topical tacrolimus or pimecrolimus. For generalized or refractory disease, options include narrowband UVB or PUVA phototherapy, hydroxychloroquine 200–400 mg daily, dapsone 50–100 mg daily, isotretinoin 0.5–1 mg/kg/day, methotrexate 7.5–25 mg weekly and biologics such as adalimumab.

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Q6: Prognosis and complications (2 min)

What is the prognosis of localized granuloma annulare? What are the main complications or pitfalls?

^[1]Model answer: Localized GA has an excellent prognosis; 50–75% of cases resolve spontaneously within months to years, although recurrence is common. The main complications are cosmetic concern and diagnostic confusion with tinea or other annular lesions. Pitfalls include over-treating self-limiting localized disease, failing to screen for systemic disease in generalized GA, and missing atypical mimics such as sarcoidosis, necrobiosis lipoidica or cutaneous lymphoma.

References10ShowHide

1. [1]Joshi TP, Duvic M. Granuloma Annulare: An Updated Review of Epidemiology, Pathogenesis, and Treatment Options Am J Clin Dermatol, 2022.PMID 34495491
2. [2]Giorgio CM, Balato A, Licata G, et al. Successful Treatment of Refractory Generalized Granuloma Annulare with Abrocitinib Dermatol Rep, 2026.PMID 41574570
3. [3]Nordmann TM, Kim JR, Dummer R, et al. A Monocentric, Retrospective Analysis of 61 Patients with Generalized Granuloma Annulare Dermatology, 2020.PMID 32403113
4. [4]Nordmann TM, Kim JR, Dummer R, et al. A Monocentric, Retrospective Analysis of 61 Patients with Generalized Granuloma Annulare Dermatology, 2020.PMID 32403113
5. [5]Nordmann TM, Kim JR, Dummer R, et al. A Monocentric, Retrospective Analysis of 61 Patients with Generalized Granuloma Annulare Dermatology, 2020.PMID 32403113
6. [6]Nordmann TM, Kim JR, Dummer R, et al. A Monocentric, Retrospective Analysis of 61 Patients with Generalized Granuloma Annulare Dermatology, 2020.PMID 32403113
7. [7]Giorgio CM, Balato A, Licata G, et al. Successful Treatment of Refractory Generalized Granuloma Annulare with Abrocitinib Dermatol Rep, 2026.PMID 41574570
8. [8]Nordmann TM, Kim JR, Dummer R, et al. A Monocentric, Retrospective Analysis of 61 Patients with Generalized Granuloma Annulare Dermatology, 2020.PMID 32403113
9. [9]Joshi TP, Duvic M. Granuloma Annulare: An Updated Review of Epidemiology, Pathogenesis, and Treatment Options Am J Clin Dermatol, 2022.PMID 34495491
10. [10]Joshi TP, Duvic M. Granuloma Annulare: An Updated Review of Epidemiology, Pathogenesis, and Treatment Options Am J Clin Dermatol, 2022.PMID 34495491