Successful treatment of tumor-induced osteomalacia causing by phosphaturic mesenchymal tumor of the foot

Abstract

Tumor-induced osteomalacia causing by phosphaturic mesenchymal tumor of the foot is exceedingly rare, thus may bring great challenges to the timely and proper diagnosis and treatment of clinicians. The only definitive management is removal of the phosphaturic mesenchymal tumor completely. The objective of this article is to report 2 unusual cases with tumor-induced osteomalacia causing by phosphaturic mesenchymal tumor of the foot. We describe 2 patients with phosphaturic mesenchymal tumor involving the foot who were successfully treated with tumor resection. On presentation to our institution, the patients both had signs of severe osteomalacia, and the patients’ most outstanding complaints were diffuse bone pain, general weakness, and disabled walking. A 53-year-old female underwent surgical excision of pathogenic tumor on the sole of left foot. A 62-year-old female underwent complete excision of pathogenic tumor of right plantar. The patients showed appropriate destruction of the tumor, adequate pain relief, and the elevated blood phosphorus levels compared with the previous status. Surgical resection is the most effective treatment option for patients with tumor-induced osteomalacia who can undergo appropriate surgical treatment. This represents a safe and reasonable approach to sustainably relieve pain and other symptoms with tumor-induced osteomalacia in the foot.

Renal Phosphate Wasting Due to Tumor-Induced (Oncogenic) Osteomalacia

“…Once this is confirmed, additional lab workup can be done; this includes 1,25-dihydroxyvitamin D, calcium, and PTH levels. The measurement of FGF-23 is now also available and aids in the diagnosis of TIO [ 7 , 9 ]. While circulating FGF-23 levels are elevated in other hypophosphatemic conditions like autosomal dominant hypophosphatemic rickets, X-linked hypophosphatemic rickets, and autosomal recessive hypophosphatemic rickets, TIO can be distinguished from them by the presence of normal serum PTH and calcium levels with low or inappropriately normal 1,25-dihydroxyvitamin D levels [ 3 , 7 ].…”

“…The detection of these tumors, however, is often difficult due to their small size and slow growth, which may not be picked up on physical exam or imaging. This, as well as the rarity of the condition, often results in delayed diagnosis and treatment [ 9 , 11 ]. The average time from the onset of symptoms to a correct diagnosis often exceeds 2.5 years [ 7 ].…”

“…The localization of tumors missed by computer tomography (CT), MRI, or even positron emission tomography (PET)-CT may be enhanced by the use of somatostatin-aided scintigraphy [ 7 ]. Surgical removal of the tumor is the only definitive treatment [ 9 , 11 ]. However, while patients have a good prognosis following surgical resection, recurrence may occur, affecting approximately 7% of patients who undergo surgery [ 7 , 9 ].…”

“…While the prevalence of TIO is currently unknown, since its first description in 1947 by McCance [6], approximately 500 cases have been reported in the literature [7][8][9]. The diagnosis is often challenging due to the rarity of this condition as well as its nonspecific presentations, such as bone pain, muscle weakness, and fractures [7,8,10].…”

Revisiting the WHO classification system of soft tissue tumours: emphasis on advanced magnetic resonance imaging sequences. Part 1

“…PMT, which is classified as a rarely metastasising lesion, is an extremely rare but clinically and histologically distinctive tumour that produces fibroblast growth factor 23, a hormone that blocks the reuptake of phosphate by proximal renal tubule, resulting in phosphaturia [ 33 ]. As such, PMTs produce phosphaturia and result in tumour-induced osteomalacia, which resolves with complete PMT excision [ 34 ]. Clinically, the majority of patients with PMT exhibit elevated serum levels of fibroblast growth factor 23 [ 33 ].…”