Lichen scrofulosorum

Hebra 1860.

Tuberculosis cutis lichenoides.

Lichen scrofulosorum is a rare cutaneous manifestation of tuberculosis characterized by a lichenoid papular eruption, reflecting a hypersensitivity reaction to mycobacterial antigens in individuals with a strong immune response.

Primarily affects children and adolescents. It is considered a tuberculid and is rare overall. Often associated with latent or active tuberculosis.

Classified among the tuberculids—hypersensitivity reactions to systemic mycobacterial infection, with no detectable organisms in skin lesions.

Represents a type IV hypersensitivity reaction to disseminated mycobacterial antigens. Typically occurs in the presence of a latent or active tuberculosis focus, often without bacilli detectable in skin lesions.

Multiple, symmetrically distributed, perifollicular, erythematous to yellow-brown papules. Most commonly appear on the lateral trunk. Lesions are non-pruritic and may be asymptomatic. Systemic symptoms such as low-grade fever are infrequent.

Diagnosis is based on clinical findings, supported by:

• Positive tuberculin skin test (Mantoux test)

• Interferon-gamma release assay (e.g., Quantiferon®)

• Skin biopsy

• Imaging: Chest X-ray or CT to exclude pulmonary tuberculosis

• Abdominal and renal ultrasound

• Three consecutive early-morning sputum and urine samples

• Bronchoalveolar lavage if pulmonary TB is suspected. Histopathology: tuberculoid granulomas with Langhans giant cells and focal necrosis.

Predominantly affects the lateral trunk; may also occur on the extremities or buttocks. Lesions are typically multiple and symmetrical.

History of tuberculosis or exposure. In some cases, lichen scrofulosorum may be the first sign of undiagnosed systemic tuberculosis.

Histologically, non-caseating or necrotizing granulomas composed of epithelioid cells and Langhans giant cells in the upper dermis. Acid-fast bacilli are usually absent.

Rare. Possible progression to cutaneous or systemic tuberculosis if underlying infection is untreated. Cosmetic concerns may lead to psychological distress.

Screening and treatment of latent or active tuberculosis. Evaluation of close contacts is recommended.

Generally favorable. Spontaneous resolution may occur within weeks. Recurrence is possible in cases of untreated or inadequately treated systemic TB.

Systemic anti-tuberculosis therapy according to WHO/CDC guidelines:

Intensive phase (2 months)

• Rifampicin 10 mg/kg body weight/day orally

• Isoniazid 5 mg/kg body weight/day orally + Vitamin B6

• Pyrazinamide 35 mg/kg body weight/day orally (consider allopurinol co-medication)

• Ethambutol 15 mg/kg body weight/day orally

Continuation phase (≥ 4 months)

• Rifampicin + Isoniazid

• Ethambutol can be discontinued if no resistance is present

• For HIV-positive patients: duration ≥ 7 months; Ethambutol may be replaced by streptomycin 15–20 mg/kg/day orally (max. 750 mg for patients >60 years)

Total treatment duration should be at least 6 months, ideally continued for 12–24 months after complete resolution of skin lesions.

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