Using 18F-FDG PET/CT to Detect an Occult Mesenchymal Tumor Causing Oncogenic Osteomalacia

Abstract

Oncogenic osteomalacia is a rare paraneoplastic syndrome characterized by renal phosphate excretion, hypophosphatemia, and osteomalacia. This syndrome is often caused by tumors of mesenchymal origin. Patients with oncogenic osteomalacia have abnormal bone mineralization, resulting in a high frequency of fractures. Tumor resection is the treatment of choice, as it will often correct the metabolic imbalance. Although oncogenic osteomalacia is a potentially curable disease, diagnosis is difficult and often delayed because of the small size and sporadic location of the tumor. Bone scintigraphy and radiography best characterize osteomalacia; magnetic resonance imaging findings are nonspecific. Here, we report a case of oncogenic osteomalacia secondary to a phosphaturic mesenchymal tumor that was successfully detected by 18 F-fluorodeoxyglucose positron emission tomography/computed tomography ( 18 F-FDG PET/CT). This case illustrates the advantages of 18 F-FDG PET/CT in detecting the occult mesenchymal tumor that causes oncogenic osteomalacia.

Occult tumour-induced osteomalacia causing lesion detected by FDG-PET/CT scan

“…In literature, cases have been reported for detecting occult mesenchymal lesion using FDG PET-CT scan. [ 8 ] As seen in our case, there was a delay in diagnosis as initial investigations failed to locate the lesions. Whole-body FDG PET-CT scan was useful in diagnosis, thus leading to appropriate treatment.…”

Successful Localization Using 68Ga-DOTATOC PET/CT of a Phosphaturic Mesenchymal Tumor Causing Osteomalacia in a Patient with Concurrent Follicular Lymphoma

“…Because of the limitations of conventional imaging modalities, various combinations of functional and anatomical imaging are often used diagnostically, with many studies recommending 18 F-FDG PET to locate PMTs [25][26][27]. Because PMTs usually express somatostatin receptor type 2A [5,28], somatostatin receptor PET/CT, such as 68 Ga-DOTATATE, 68 Ga-DOTATOC, or 68 Ga-DOTANOC PET/CT, has been used to detect PMTs [29].…”

Glomus tumor as a cause of oncogenic osteomalacia

“…According to the previously reported cases in literature, difficulty in tumor detection, results in a considerable delay in diagnosis and consequently a delay between the onset of symptoms and surgical resection (18). Patients with oncogenic osteomalacia present with nonspecific symptoms including fatigue, bone pain, and musculoskeletal weakness that make some difficulty in diagnosis and often lead to a delay in treatment.…”