P018 A rare case of adolescent lupus vulgaris secondary to neonatal bacille Calmette-Guérin vaccination

Abstract

Lupus vulgaris (LV) is a paucibacillary form of cutaneous tuberculosis. LV arising as a complication of bacille Calmette–Guérin (BCG) vaccination is extremely uncommon (Jayasekera P, Khirwadkar N, Sharpe G. A young man with expanding atrophic lesions, Clin Exp Dermatol 2015; 40: 94–6), with adolescent-onset presentations being notably rare. We report an immunocompetent 17-year-old with BCG-associated LV developing more than a decade after neonatal vaccination. The patient presented with a 2-year history of two erythematous–violaceous plaques on the extensor surface of the left upper arm. They were tender and discharged clear fluid intermittently but also bled when traumatized. Systemic review was unremarkable. Laboratory investigations were normal, including full blood count and renal and liver profiles. QuantiFERON and HIV screen were negative. Chest radiograph excluded active pulmonary disease. Histology from a skin biopsy demonstrated noncaseating granuloma with a predominance of Langhans-type giant cells. Special stains were negative. Tissue culture grew Mycobacterium tuberculosis complex, while polymerase chain reaction (PCR) confirmed pyrazinamide-resistant mycobacteria consistent with BCG-derived Mycobacterium bovis. History revealed neonatal BCG vaccination administration. The patient initially received 2 months of rifampicin, isoniazid, ethambutol and pyrazinamide with pyridoxine, followed by 7 months of rifampicin and isoniazid. Significant clinical improvement occurred. BCG-associated LV has a reported incidence of approximately 1 per 100 000–175 000 vaccinations and typically appears within 1 year (Attia E. BCG vaccine-induced lupus vulgaris. Eur J Dermatol 2007; 17: 547–8). Adolescent cases are exceptionally rare. Diagnosis can be challenging due to paucibacillary histology and negative acid-fast staining. PCR and culture remain definitive. Early recognition prevents long-term complications such as severe ulceration, site abscesses, granuloma formation, keloid scarring, eczematization, scrofuloderma, suppurative lymphadenitis and osteitis/osteomyelitis. This case highlights the need to consider BCG-induced LV in persistent plaques at prior vaccination sites, despite occurrence several years after immunization.