Papulonecrotic tuberculid-like eruptions after Bacille Calmette-Guerin vaccination

One of the specific skin lesions occurring after Bacille Calmette-Guerin (BCG) vaccination is generalized tuberculid-like eruptions, which occur rarely, but have a tendency to heal spontaneously. Their pathogenesis and relationship to "true" tuberculids are poorly understood. This report presents a case of a 6-month-old girl who developed generalized papulonecrotic tuberculid-like eruptions after BCG vaccination. The skin lesions healed spontaneously in 3 months. Culture of blood, gastric juice and reverse transcription polymerase chain reaction (RT-PCR) of papulonecrotic skin biopsies were all negative for Mycobacterium tuberculosis. Histopathology of papulonecrotic eruptions revealed marked epidermal necrosis, perivascular lymphocytic infiltrates and epidermotropic infiltration of lymphocytes showing markers of CD3(+) lymphocytes (90-95% of all infiltrating cells), CD4(+) (40-50%), CD8(+) (40-50%), and CD45RO(+) (70%). In contrast, the BCG vaccination site revealed intradermal granuloma with epithelioid cells, occasional giant cells and infiltration of lymphocytes consisting of CD3(+) (60-70%), CD4(+) (40-50%), CD8(+) (30-40%), CD45RO(+) (40%), CD79a(+) (30-40%), and CD20(+) (20-30%). Our patient did not reveal any signs indicative of tuberculosis. Papulonecrotic lesions were therefore called papulonecrotic tuberculid-like eruptions, rather than tuberculids, that occurred after BCG vaccination and appeared to derive from a hypersensitive reaction mediated by immune lymphocytic infiltration.