A 17-year-old girl was operated for a solitary well-circumscribed pulmonary parenchymal tumor and reoperated ten times for multiple recurrent similar pulmonary tumors during 24 years. Histologic examination revealed the so-called intravascular bronchioloalveolar tumor (IVBAT) in all instances. The patient died from pneumonia superimposed on decreased respiratory function 24 years after the onset of disease. This is the longest survival so far reported in IVBAT. The treatment was surgical in all phases of the disease, and the patient did not receive radiotherapy or cytostatic drug therapy. Mediastinal and pleural tumor nodules were removed 17 years from the first pulmonary operation, and 24 years after the first operation a fibrous tumor was removed from the retroperitoneal space. Immunohistologically, the tumor cells were positive for vimentin-type of intermediate filaments, in line with their mesenchymal nature. Endothelial markers, Factor VIII-related antigen and Ulex europaeus I lectin binding, were not found in convincingly neoplastic cells, and Schwann cell, epithelial cell, muscle cell, and histiocytic markers were absent. Thus, IVBAT appears to be a low-grade malignant mesenchymal neoplasm, composed of poorly differentiated mesenchymal cells, whose exact nature remains undefined with the currently used cell-type markers.