What is the diagnosis and treatment for non-pruritic, non-painful, ring-like pink plaques with paler centers persisting for 6 months?

Diagnosis: Granuloma Annulare

The clinical presentation of non-pruritic, non-painful, ring-like pink plaques with paler centers persisting for 6 months to 1 year is most consistent with granuloma annulare, a benign inflammatory dermatosis that requires no treatment in most cases but can be managed with topical or intralesional corticosteroids if cosmetically concerning. 1

Clinical Features Supporting This Diagnosis

The key diagnostic features that distinguish this presentation include:

• Annular configuration with central clearing: Ring-like plaques with paler centers are characteristic of granuloma annulare, appearing as pink to red lesions that expand centrifugally 1
• Absence of symptoms: The lack of pruritus and pain effectively excludes tinea corporis (typically pruritic), nummular eczema (intensely pruritic), and inflammatory conditions 1
• Chronic duration: Persistence for 6-12 months without significant change is typical of granuloma annulare, which follows an indolent course 1
• Body distribution: Lesions on the trunk and extremities are common sites for generalized granuloma annulare 1

Differential Diagnosis to Exclude

While granuloma annulare is most likely, consider these alternatives based on specific features:

• Tinea corporis: Would show scale at the advancing border and be pruritic; confirm with potassium hydroxide examination of skin scrapings showing hyphae 1, 2
• Erythema multiforme: Presents with raised lesions (not flat plaques) and typically has acute onset with mucosal involvement 1, 3
• Subacute cutaneous lupus erythematosus: Would show photosensitivity and typically has scale; requires antinuclear antibody testing 1
• Hansen disease (leprosy): Would demonstrate sensory loss within lesions; the patient's reported numbness warrants evaluation but is not typical for granuloma annulare 4, 1

Diagnostic Workup

Obtain a 4-mm punch biopsy from an active lesion edge to confirm the diagnosis histologically, looking for:

• Palisading granulomas with central mucin deposition
• Absence of fungal elements
• Lymphohistiocytic infiltrate in the dermis 4

Laboratory evaluation should include:

• Fasting glucose and hemoglobin A1c (granuloma annulare can be associated with diabetes mellitus in up to 4.1% of cases) 5
• Complete blood count and erythrocyte sedimentation rate to exclude systemic disease 4
• Thyroid function tests if clinically indicated 5

Treatment Algorithm

For Localized Disease (Few Lesions)

First-line: Observation alone is appropriate, as 50% of cases resolve spontaneously within 2 years 1

If treatment desired for cosmetic reasons:

• High-potency topical corticosteroids (clobetasol propionate 0.05%) applied twice daily under occlusion for 4-6 weeks 1
• Intralesional triamcinolone acetonide (5-10 mg/mL) injected into the border of lesions every 4-6 weeks 1

For Generalized Disease (Multiple Body Sites)

First-line systemic options:

• Narrow-band UVB phototherapy 3 times weekly for 12-24 weeks 1
• PUVA therapy if narrow-band UVB fails 6

Second-line for refractory cases:

• Oral dapsone 50-100 mg daily (check G6PD level first) 1
• Hydroxychloroquine 200-400 mg daily 1

Critical Pitfalls to Avoid

Do not misdiagnose as urticaria: The patient's previous diagnosis of chronic urticaria was incorrect—urticaria presents with transient wheals lasting <24 hours with blanched centers, not persistent plaques lasting months 1

Do not treat empirically with antifungals: Unlike tinea corporis, granuloma annulare lacks scale and will not respond to antifungal therapy; confirm with KOH examination before prescribing antifungals 1, 2

Do not overlook associated systemic disease: While granuloma annulare is typically idiopathic, screen for diabetes mellitus, thyroid disease, and hyperlipidemia, particularly in generalized cases 5

Evaluate the reported numbness separately: The patient's numbness in fingers and feet is not explained by granuloma annulare and warrants neurologic evaluation to exclude peripheral neuropathy from diabetes or other causes 4

Follow-Up Recommendations

• Reassess at 3-month intervals if observation is chosen
• Document lesion size, number, and distribution with photography
• Repeat metabolic screening annually if initial workup is normal
• Consider biopsy if lesions change character, become symptomatic, or fail to respond to appropriate therapy 4