Oral 6, Cutaneous tuberculosis in an infant

An 8‐month‐old white boy was referred to our department with an 18‐week history of a widespread rash, previously diagnosed as molluscum contagiosum and subsequently as infected Giannotti–Crosti syndrome. His rash started on the arms, and had spread to the forearms, legs and face with lesions coming in crops. Medical history was unremarkable and his vaccinations were up to date, including neonatal bacillus Calmette–Guérin. Treatments including oral erythromycin, topical fusidic acid and a variety of emollients had given no improvement. Both parents were on treatment for pulmonary tuberculosis. On examination, he was thriving (50th centile for height, 75th centile for weight). Lesions consisted of erythematous papules and plaques, with induration and central ulceration. A 3 × 3 cm left submandibular swelling was firm, painless and nonfluctuant. This had been gradually enlarging over a 3‐month period. A Mantoux test (2 TU) showed 17 mm of induration at 48 h. Patchy consolidation was present on chest X‐ray. A 4‐mm punch biopsy showed a mildly dispersed inflammatory infiltrate with Langerhans giant multinucleated cells in the dermis and several distinct granulomas. Two months after starting antituberculous therapy his lymphadenopathy and skin lesions had resolved with some residual scarring. Mycobacterium tuberculosis can induce a variety of cutaneous changes. Papulonecrotic tuberculids due to haematogenous dissemination typically affect the extensor aspects of the extremities and occur in symmetrical crops. A high level of suspicion for tuberculosis should be maintained in otherwise healthy children with a persistent skin rash. Misdiagnosis, neglect or late diagnosis in children may result in extensive disease.