The second case was a 32-year-old man who was admitted to hospital with generalized pain for more than a year. One year before admission, the man had no obvious inducement of foot pain, which was aggravated after weight-bearing activities and exercise, and then gradually developed upward to both lower limbs, bilateral hip joints, ribs, and shoulder blades. The degree of pain gradually increased, accompanied by walking, turning over and bending difficulties, and morning stiffness. No obvious abnormality was found in physical examination. In addition, serological examination showed that blood phosphorus was 0.59 mmol/L (reference value range: 0.86-1.78 mmol/L), alkaline phosphatase was 471.8 u/L (reference value range: 45.0-125.0 u/L), and blood calcium was in the normal range (Table 1). And PET-CT showed a slightly low-density nodule in the inner muscle of the right middle thigh, about 1.5 cm x 1.8 cm in size, with increased expression of somatostatin receptors: the possibility of phosphaturic mesenchymal tumor (Figure 3). Then, surgical excision of the lesion was performed. The histology of the postoperative specimens showed that the tumor was composed of bland short spindle cells. Smudgy/grungy basophilic matrix, hemangiopericytomatous-like blood vessels, a small number of thick walled vessels, a little adipose tissue, hemorrhage, focal ossification, multinucleated giant cells, and focal myxoid degeneration could be seen (Figure 4).Immunohistochemical staining showed positive for vimentin, SATB2, and CD56, but negative for CD31, CD34, desmin, CD99, Bcl-2, S-100, Syn, CK-pan, and STAT6. And there was some nonspecific staining for SMA. The proliferation index Ki-67 was about 1% (Table 2). Compared with preoperative, the patient's serum phosphorus showed an overall upward trend and completely returned to normal levels on the second postoperative day.