A 31-year-old woman who is an intravenous drug abuser developed sternoclavi
cular joint infection with mediastinal and subcutaneous tissue abscesses th
at communicated through an erosion in the manubrium caused by osteomyelitis
. Air entrapment from a subsequent apical pneumothorax formed a localized a
nterior "pneumothoracocele." We referred to this condition as "pneumothorax
necessitans," and we suggest including it in the differential diagnosis of
anterior chest wall masses. (C) 2000 by The Society of Thoracic Surgeons.