Phosphaturie mesenchymal tumour, 'non-phosphaturic' variant: a case report and review of the literature

Reubina Wadee,Abdullah Ismail,Z Linda

doi:10.17159/2309-8309/2021/v20n3a7

Abstract

ABSTRACT BACKGROUND: Phosphaturic mesenchymal tumours are uncommon neoplasms, usually associated with tumour-induced osteomalacia, that occur in middle-aged adults but have been reported at the extremes of age. The 'non-phosphaturic' variant is even rarer METHODS: Herein, we describe the non-phosphaturic variant in a 12-year-old male who presented to the Department of Orthopaedic Surgery with a six-month history of painful progressive swelling of his right forearm in the absence of trauma. He had no other significant symptoms RESULTS: The patient had normal serum calcium and phosphate levels on biochemical analysis. An inci-sional biopsy was performed and a histopathological diagnosis of a phosphaturic mesenchymal tumour, non-phosphaturic variant, was rendered. Six weeks later, he underwent surgical excision of a 15x15 cm soft tissue mass from his right forearm. He had an uneventful postoperative period and was discharged. He has been followed up at the outpatient department and has been free of tumour recurrence for over 18 months since his surgery with no evidence of osteomalacia and no other tumours CONCLUSION: Phosphaturic mesenchymal tumours are rare mesenchymal neoplasms and their microscopically identical counterpart without phosphaturia, known as the 'non-phosphaturic' variant, is even more uncommon and may prove a greater diagnostic challenge. While the diagnosis may be confirmed by hypophosphataemia and phosphaturia secondary to the paraneoplastic phenomenon of tumour-induced osteomalacia, there may be instances, such as with our patient, where tumour-induced osteomalacia is absent. This case underscores the importance of clinicopathological correlation together with a wide differential diagnosis required to arrive at a correct diagnosis to facilitate appropriate patient management Level of evidence: Level 5 Keywords: phosphaturic mesenchymal tumours, non-phosphaturic variant

Highlights

IntroductionPhosphaturic mesenchymal tumours (PMTs) are rare neoplasms that are usually associated with renal phosphate loss and tumourinduced osteomalacia (TIO).[1]
While the diagnosis may be confirmed by hypophosphataemia and phosphaturia secondary to the paraneoplastic phenomenon of tumour-induced osteomalacia, there may be instances, such as with our patient, where tumourinduced osteomalacia is absent
This case underscores the importance of clinicopathological correlation together with a wide differential diagnosis required to arrive at a correct diagnosis to facilitate appropriate patient management

Summary

Introduction

Phosphaturic mesenchymal tumours (PMTs) are rare neoplasms that are usually associated with renal phosphate loss and tumourinduced osteomalacia (TIO).[1]. Cases of PMT may not demonstrate TIO and as such, are referred to as ‘non-phosphaturic’ variants.[5] A histological diagnosis in these circumstances may be confirmed by a comprehensive immunohistochemical panel excluding other tumours and by the detection of FGF23 transcripts using reverse transcription-polymerase chain reaction (RT-PCR) or in-situ hybridisation.[5]. Phosphaturic mesenchymal tumours are uncommon neoplasms, usually associated with tumourinduced osteomalacia, that occur in middle-aged adults but have been reported at the extremes of age.

Results

Discussion

Conclusion