Chondromyxoid fibroma of rib; report of an unusual benign primary tumor.

Metastatic tumors in ribs are fairly common and if the primary neoplasm is recognized the diagnosis of metastasis is usually not difficult and can be confirmed by aspiration biopsy. Primary tumors in ribs, on the other hand, are much less common and frequently no definite diagnosis can be made until the neoplasm is resected and submitted to a competent pathologist. In reviewing the available literature one is impressed with the relative scarcity of reported primary tumors in ribs. Over a period of 20 years Janess of Toronto encountered only eight primary tumors in ribs. There are two reports in the recent literature which bring the material on primary tumors in ribs to date: in 1942 Sommer and Majorla collected 66 cases of proved primary neoplasms in ribs reported since 1933 and added 15 of their own from the University of Michigan Hospital; and in 1948 Dorner and Marcys collected 47 cases of proved primary tumors and tumor-like lesions in ribs reported since 1942 and added eight of their own which they encountered over a 12-year period a t the University of Iowa Hospital. As indicated in the table, less than half of the lesions in the group of 55 cases reported by Dorner and Marcy were true neoplasms; the remaining lesions were classified as fibrous dysplasia, a term introduced by Lichtenstein6Jo to describe a perfectly benign lesion of the bone which is not a neoplasm but which results from perverted activity of the specific bone-forming mesenchyme. The 24 primary tumors of the rib comprising the group of Dorner and Marcy were represented by the following: chondrosarcoma eight, osteochondroma four, fibrosarcoma, chondroma and hemangioma two of each, osteosarcoma, lymphocytoma, osteoid osteoma, plasmocytoma, osteochondrosarcoma and osteochondromyxosarcoma one each. A case of osteochondroma of the first rib producing Horner's syndrome was reported in 1948." The total number of proved primary tumors in ribs reported since 1933 is only 106. Where no diagnosis is available and primary rib tumor is suspected surgical exploration is preferable to watchful waiting so as not to overlook a frankly malignant tumor or one in the pre-