Phosphaturic mesenchymal tumor of the occipitocervical region: Report of two rare cases and literature review

Abstract BackgroundTumor-induced osteomalacia (TIO) is regarded as a rare paraneoplastic syndrome mainly caused by phosphaturic mesenchymal tumor (PMT). To our known, only 5 occipitocervical PMTs have been described in the world’s English literature. We reported two rare cases of occipitocervical PMT, and conducted a retrospective analysis of these 7 cases. The purpose of this study is to discuss the clinical characteristics and treatment of occipitocervical PMT.Case PresentationBoth patients were middle-aged females, and had a long-standing bone pain. In case 1, there were no abnormalities in biochemical indicators. The blood phosphorus was normal and alkaline phosphatase (ALP) was elevated in case 2. Magnetic resonance imaging (MRI) suggested that osteolytic bone destruction accompanied by a soft tissue mass in left C1-2 vertebra (case 1). In case 2, the bone destruction was located on the right C1-2 and the clivus. Then both patients underwent complete resection of tumor, and case 2 also received adjuvant radiotherapy, the histopathology revealed a PMT. Case 2 suffered recurrence during 5-year follow-up.ConclusionsOccipitocervical PMT is quite rare, and only 5 cases have been reported in the literature. Currently, complete resection of the tumor is the best option. The surgery is difficult, and requires delicate operation due to the complex anatomy of the occipitocervical region. Postoperative radiotherapy has little effect on local control. And further research is needed to confirm the effectiveness of the newly-emerged therapies.