Perforating Granuloma Annulare Mimicking Papulonecrotic Tuberculid

Area of Science:

• Dermatology
• Pathology

Background:

• Perforating granuloma annulare (PGA) is a rare variant of granuloma annulare.
• PGA presents clinically as an umbilicated papule with a central crust, often mistaken for papulonecrotic tuberculid (PNT).
• PNT is typically associated with tuberculosis infection and shows wedge-shaped dermal necrosis histologically.

Observation:

• A 43-year-old Korean woman presented with a year-long history of erythematous papules on her limbs.
• The patient had latent tuberculosis and was undergoing antituberculous medication, complicating the initial diagnosis.
• Despite treatment for tuberculosis, her skin lesions persisted, prompting further investigation.

Findings:

• Histopathological examination revealed wedge-shaped dermal necrosis, focal mucin deposition, and palisading granulomatous inflammation.
• These findings, along with clinical presentation, led to a diagnosis of PGA, distinct from PNT.
• The patient responded well to topical corticosteroid treatment.

Implications:

• This case highlights the importance of considering PGA in the differential diagnosis of PNT, especially when clinical and histological features overlap.
• Accurate diagnosis is crucial for appropriate treatment, as PGA and PNT require different management strategies.
• The successful treatment of PGA with topical corticosteroids suggests their efficacy in managing this rare condition.