Usefulness of 68Ga-DOTATOC PET/CT to localize the culprit tumor inducing osteomalacia

Dong Yun Lee,Jung-Min Koh,Seung Hun Lee,Seung Jun Oh,Wanlim Kim,Beom-Jun Kim,Sang Ju Lee,Pil Whan Yoon,Jin-Sook Ryu

doi:10.1038/s41598-021-81491-2

Dong Yun Lee, Jung-Min Koh + Show 7 more

Open Access

https://doi.org/10.1038/s41598-021-81491-2

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Abstract

Tumor-induced osteomalacia (TIO) is an uncommon paraneoplastic syndrome presenting with sustained hypophosphatemia. Treatment of choice is removal of the tumor causing the TIO, but identification of the culprit tumor by routine imaging is challenging. This study aimed to assess the usefulness of somatostatin receptor imaging, called 68Ga-DOTATOC PET/CT, in the management of patients with TIO. Twelve patients who were suspected of having TIO underwent 68Ga-DOTATOC PET/CT. Lesion detectability and maximum standardized uptake value (SUVmax) were determined and retrospectively compared with the clinical/imaging surveillance and histopathologic diagnosis. The median duration of suspected TIO with hypophosphatemia was 7.8 years (range 2.1–21.0). Conventional radiologic and/or nuclear medicine images failed to identify the culprit tumors. However, 68Ga-DOTATOC PET/CT scans showed that 8 of the 12 patients had positive lesions, suggesting the presence of focal culprit tumors. The SUVmax of positive tumors was 1.9–45.7 (median: 11.5). Six skeletal lesions and two extra-skeletal lesions were identified. Seven of the lesions were pathologically confirmed as potential culprits of TIO. Hypophosphatemia was resolved in five patients who underwent lesion excision. The 68Ga-DOTATOC PET/CT is a useful whole-body imaging modality for the detection of causative tumors in patients with suspected TIO.

Highlights

Tumor-induced osteomalacia (TIO), known as oncogenic hypophosphatemic osteomalacia, is an uncommon paraneoplastic syndrome[1]
Six skeletal lesions were located in the second cervical vertebral body (C2), third lumbar vertebral body, pubic bone, femur, maxilla, and fibula and two extra-skeletal lesions were located in the groin and thigh
We detected the culprit tumors that induced osteomalacia in seven out of nine patients whose calculated tubular reabsorption of phosphate (TRP) was suggestive of renal h ypophosphatemia[26]

Summary

Introduction

Tumor-induced osteomalacia (TIO), known as oncogenic hypophosphatemic osteomalacia, is an uncommon paraneoplastic syndrome[1]. TIO is a very rare disease, the suspicion of TIO and detection of the culprit tumor is essential, given the long-term debilitating morbidity associated with aberrant bone metabolism. The discovery of somatostatin receptor (SSTR) overexpression in mesenchymal tumors[17], especially type 2 SSTR, prompted specific imaging of TIO patients using 111Indium-based octreotide scans, which are classic SSTR targeting scintigraphy[18]. Recent reports demonstrated improved localization of culprit tumors in TIO using these PET radiotracers[13,20,21]. Several reports have demonstrated the performance of 68Ga-DOTATOC PET/CT in these cohorts. In this context, we investigated the usefulness of 68Ga-DOTATOC PET/CT for the management of patients with TIO from a single Korean tertiary hospital

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