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

🧾 Clinical Case – Lupus Vulgaris

A 42-year-old woman presents with a slowly enlarging, reddish-brown plaque with an “apple jelly” appearance on her cheek, present for 2 years. She reports mild itching but no systemic symptoms. Skin biopsy shows granulomatous inflammation with caseating necrosis, and cultures confirm Mycobacterium tuberculosis. Diagnosis: Lupus vulgaris, a cutaneous form of TB. She was started on standard anti-tuberculous therapy with good clinical response.

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Lupus Vulgaris