Makindo Medical Notes

Multiple red-brown nodules with a soft, jelly-like consistency are classically described as “apple-jelly nodules” 🍎, a hallmark of Lupus Vulgaris.

Severe, chronic cutaneous tuberculosis with scarring, atrophy, and disfigurement if untreated.

📖 About

• Represents cutaneous invasion by Mycobacterium tuberculosis.
• Chronic, progressive, and destructive skin disease.
• Occurs in patients with a moderate to high degree of immunity (reactivation TB).
• More common in females than males 👩.

🧬 Aetiology

• Direct extension from underlying TB focus (lymph node, bone, joint, mucosa).
• Haematogenous or lymphatic spread from a primary TB site.
• Exogenous inoculation (rare).

🩺 Clinical Features

• Reddish-brown plaques with peripheral extension and central healing → atrophy and scarring.
• Apple-jelly nodules 🍎 visible on diascopy (pressing glass slide on lesion).
• Most common sites:
  • Head and neck (≈80%).
  • Followed by arms, legs, then trunk.
• Lesions may ulcerate or form disfiguring scars.
• Longstanding disease → risk of malignant transformation (SCC).

🔍 Differentials

• Sarcoidosis (also produces “apple-jelly” appearance).
• Leprosy (especially tuberculoid form).
• Lupus erythematosus (DLE).
• Deep fungal infections (sporotrichosis, chromoblastomycosis).
• Cutaneous leishmaniasis.

🧪 Investigations

• Baseline bloods: FBC, U&E, LFTs.
• Screen for systemic TB: CXR, sputum AFB, HIV test.
• Skin biopsy: granulomatous inflammation with caseating necrosis, Ziehl-Neelsen staining (may show few bacilli).
• Culture for Mycobacterium tuberculosis (gold standard, but slow growth).
• Molecular tests: PCR for TB DNA (faster diagnosis).

💊 Management

• Treat as for tuberculosis using standard anti-TB therapy (RIPE regimen: Rifampicin, Isoniazid, Pyrazinamide, Ethambutol).
• Duration: usually 6 months; longer if extensive or resistant disease.
• Reconstructive surgery may be needed for disfigurement or functional impairment.
• Monitor for secondary bacterial infection and skin malignancy in chronic scars.

📚 References

• Rook’s Textbook of Dermatology – Cutaneous Tuberculosis.
• WHO Guidelines for Tuberculosis Management.
• DermNet NZ – Lupus Vulgaris