Papulonecrotic tuberculid in an HIV-positive patient.

We present a 33-year-old HIV-positive man who presented with a two-year history of a non-itchy papular eruption, associated with night sweats, headaches, poor memory and weight loss. On examination, he had erythematous papular lesions with necrotic centres on the face, arms and torso with no systemic abnormalities. A skin biopsy eventually led to the diagnosis of papulonecrotic tuberculid, and treatment with quadruple therapy resulted in resolution of his rash and systemic symptoms. Papulonecrotic tuberculid is thought to be a immunological response to Mycobacterium bacillus components in a previously sensitized patient following haematogenous spread from a focus of infection elsewhere. Cultures from the skin are typically negative and there are no acid-fast bacilli seen, but mycobacterial DNA can be detected using polymerase chain reaction. This case is an example of the paradoxical activation of the immune system seen in patients with HIV. It highlights the importance of skin biopsy in patients with unexplained systemic symptoms and a rash, as the differential diagnosis can be wide in HIV.