Cysts of the pleura.

In contrast to the now frequently appearing and diagnosed pulmonary and bronchial carcinomata, primary tumors of the pleura are rare. Clinical differentiation of malignant tumors of the pleura from malignant tumors of the lung is essential. The most common malignant tumors of the pleura are the endotheliomata, the course of which resembles the course of an exudative tuberculous pleurisy. Benign tumors of the pleura (fibromata, osteomata, chondromata) seldom produce clinical manifestations and, therefore, are of little clinical importance. In unilateral opacities seen in the chest film, it is often difficult to make a diagnosis of specific pleural tumors. In the differential diagnosis of primary benign and malignant tumors of pleura must be included metastatic tumors, tumor-like tuberculosis, tumors of the chest wall, pleural effusion, echinococcus cysts of the pleura and the group of congenital cysts. it is the purpose of this paper to describe an addition to the group of benign tumors of the pleura, the simple cyst, which has caused some debate in recent years regarding its true nature. Fehr,’ in 1936, described a case in which roentgen inspection of the thorax disclosed a thin, sharply circumscribed shadow in the left lower pulmonary field. This lesion was situated directly above the diaphragm at the ventral side of the thorax. The patient also had a rectal carcinoma. A preliminary diagnosis of “solitary pulmonary metastasis” was abandoned, and it was assumed that some benign tumor, independent of the rectal carcinoma, was present. The patient died from surgery for the carcinoma. Autopsy disclosed a serosal cyst emanating from the diaphragmatic pleura. It was considered to be a “malformation, probably of congenital origin.” Freedman and Simon,2 in the same year, also reported a case of a single large cyst occurring in the lower zone of the left lung field. Similar cases were later reported by Pickhardt3 and Addey.4 In none of these cases was there evidence of connection of the cyst to pericardium.