CT and MRI features of phosphaturic mesenchymal tumor

The aim of the study was to study the characteristic CT and MRI features of phosphaturic mesenchymal tumors. Material and methods. CT and MRI images of 13 patients with phosphaturic mesenchymal tumors were analyzed. The size, localization, shape, contours, structure of the tumor, accumulation of contrast agent, a position relative to the cortical layer, and size of the lymph nodes were assessed. Results . Eight bone tumors (average size 23 ± 9.6 mm) and 5 soft tissue tumors (36.2 ± 47.5 mm) were detected. In patients with soft tissue tumors, the oval shape was predominant. The contours of all tumors were smooth, the tumors were adjacent to the cortical bone layer according to CT data in 75% of cases. According to MRI data, in all cases the tumors were adjacent to the cortical bone layer. In half of cases, calcifications were determined in the tumor structure. The structure of the tumor according to CT data was homogeneous, while in half of the cases, septa were visualized on MRI images. Soft tissue tumors intensively enhanced on CT and MRI. In patients with bone tumor, rounded shapes predominated. In one case, a large sacral tumor (measuring about 40 mm) prolapsed into the spinal canal. The tumors were predominantly osteolytic with sclerotic contours and were located subcortically. Osteoid or chondroid matrix in the form of calcifications was determined in the structure. According to CT data, in 3 cases the tumors intensively enhanced, in 3 cases they did not enhance, and in 1 observation there was a weak enhancement. In MRI, all lesions intensively enhanced. Conclusion . Phosphaturic mesenchymal tumor can occur in bones and soft tissues. CT and MRI allow to identify them and determine the boundaries of surgical resection, but should be used as second-line diagnostic methods after radioisotope methods. The use of a new diagnostic feature: the adjacency of bone and soft tissue formations to the cortical layer, and focusing attention by radiologists on this area may reduce the risk of “missing” the tumor.