Papulonecrotic tuberculid: a neglected disease in Western countries.
Papulonecrotic tuberculid was diagnosed in twelve young patients demonstrating symmetric scattered papulopustular necrotic lesions of the extremities. The diagnosis was supported by a strongly positive Mantoux reaction in all cases, evidence of preexisting or past tuberculosis in eight patients, characteristic histologic findings, and a prompt resolution with antituberculosis therapy. Recurrence of the skin lesions in three patients treated only with isoniazid or with para-aminosalicylic acid and isoniazid indicates the necessity for combination treatment with several antituberculosis drugs. A detailed study of twenty biopsies indicates that the primary lesion is a subacute lymphohistiocytic vasculitis that causes thrombosis and destruction of small dermal vessels. These changes lead to an infarctlike lesion with coagulation necrosis of dermal tissue. In eleven instances a well-marked palisaded histiocytic reaction was seen around necrotic areas, calling into question the differential diagnosis of granuloma annulare or Churg-Strauss granulomatosis.