PMC5399206_01
A) Bone scintigraphy with technecium-99m methylene diphosphonate revealed multiple high-uptake lesions in several sites, including the ribs and shoulders. B) PET/CT indicated the uptake of [18F] fluorodeoxyglucose in the left parotid gland with a maximum standardized uptake value (SUV) of 5.1. Contrast enhanced CT (C) and T1-weighted MRI (D) revealed the presence of the tumor in the left parotid gland.
1349-7235-56-0535-g001.jpg
PMC5399206_01_1349-7235-56-0535-g001.jpg
g001
Bone scintigraphy with technecium-99 m methylene diphosphonate showed multiple uptakes in several lesions, including the ribs and shoulders, indicating the presence of osteomalacia (Fig. 1A). Positron emission tomography-computed tomography (PET/CT) indicated the uptake of [18F] fluorodeoxyglucose in the left parotid gland region, with a maximum standardized uptake value (SUV) of 5.1 (Fig. 1B). In addition, contrast-enhanced CT and magnetic resonance imaging (MRI) confirmed the presence of a tumor in the left parotid gland region (Fig. 1C, D).
The findings from the histological and RT-PCR analyses of the tumor. A) The tumor was pathologically diagnosed as a phosphaturic mesenchymal tumor, mixed connective tissue variant (PMTMCT). The tumor and normal parotid gland tissue were continuously adjoined to each other. Small, round, spindle-shaped cells were present in the tumor. B) Distinctive vascular components and some osteoclast-like giant cells were observed. C) Total RNA was extracted using a NucleoSpin RNA (MACHEREY-NAGEL) and analyzed via RT-PCR using primers 5'-GGTGGCCTGATCCACCTGTA and 5'-TGTAATCACCACAAAGCCAGCAT. The expression of FGF23 was confirmed in the tumoral tissue but not in the adjacent normal parotid gland.
1349-7235-56-0535-g002.jpg
PMC5399206_01_1349-7235-56-0535-g002.jpg
g002
Small, round, spindle-shaped cells (Fig. 2A) and prevailing distinctive vascular components (Fig. 2B) were present in the tumor, and few mitotic figures were observed. Some osteoclast-like giant cells (Fig. 2B) were also recognized. The adjacent normal parotid tissue was negative for FGF23 expression (Fig. 2C).
The postoperative course of the patient. The FGF23 level decreased rapidly after resection of the tumor, and the serum phosphate normalized within 4 days without phosphate replacement. POD: postoperative day
1349-7235-56-0535-g003.jpg
PMC5399206_01_1349-7235-56-0535-g003.jpg
g003
After the surgery, the tenderness in the left parotid gland region improved, the FGF23 level dropped sharply to 6.5 pg/mL on postoperative day (POD) 2, and the serum phosphate normalized on POD 4 without replacement of phosphate (Fig. 3).