Mesenchymoma of the lung (so called hamartoma): a review of 154 parenchymal and endobronchial cases.

In a series of 154 patients (116 male and 38 female) with so called pulmonary hamartoma the peak incidence was in the sixth decade, with only three patients less than 20 years of age. Sequential radiographs showed that in 55 patients the tumour first appeared in adult life and that in 53 it progressively increased in size. The age incidence and progressive growth leads to the conclusion that the tumour is a benign neoplasm rather than a hamartoma, consisting of various connective tissues intersected by clefts lined by respiratory epithelium. The epithelial elements are regarded as entrapped non-neoplastic inclusions and the tumour as a purely mesenchymal neoplasm: the name mesenchymoma therefore seems the most appropriate. There were two recurrences after simple enucleation, 10 and 12 years later. A total of 142 tumours were parenchymal, and only 12 were endobronchial. All lobes were affected but there was a slight preponderance in the left upper lobe. Four patients had two (synchronous) mesenchymomas. There was an associated bronchial carcinoma in 11 patients, synchronous in six and metachronous in five.