Unveiling Hemangiopericytoma: A case demonstrating the utility of somatostatin receptor-positive metastatic hemangiopericytoma on 68Ga-DOTA TOC PET/CT

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A 34-year-old male patient was diagnosed with a left anterior meningeal hemangiopericytoma in 2016 and underwent surgical resection followed by adjuvant radiotherapy. Two years later, he developed a metastatic lesion at the D10 vertebra, which was treated with surgical decompression and postoperative radiotherapy. Recently, he presented with back pain at a tertiary care centre in Muscat, Oman, and underwent ^68^Ga-DOTATOC positron emission tomography/computed tomography (PET/CT) after a prior ^18^F-FDG PET/CT scan demonstrated low metabolic activity in the D10 vertebral lesion.

PET/CT imaging revealed an intensely ^68^Ga-DOTATOC-avid lesion at the D10 vertebra, with a maximum standardized uptake value (SUVmax) of 21.4. The corresponding CT images showed a soft tissue component encasing the prosthesis and extending into the spinal canal [Fig. 1]. Additionally, screw fixation from the D8 to D12 levels has resulted in beam-hardening artefacts at this site. The findings are consistent with tumour recurrence.

1. Comment

Hemangiopericytoma is a rare mesenchymal tumour originating from Zimmermann's pericytes, which surround capillaries and post-capillary venules.^1^ These tumours can arise in various locations, including the central nervous system, soft tissues and bones and have a high incidence of locoregional recurrence as well as distant metastasis, occurring in up to 50% of cases.^2^ Accurate diagnosis and staging are crucial for determining the appropriate treatment strategy and monitoring therapeutic response. Diagnosis and management rely on pathology and imaging modalities such as CT and magnetic resonance imaging (MRI). While MRI is essential for diagnosis and treatment planning, its accuracy may be compromised in patients with metallic implants due to artefacts and signal distortion. Moreover, MRI does not directly assess tumour metabolic activity, a key factor in treatment planning and prognosis. ^3^

Studies and clinical case reports indicate that hemangiopericytoma exhibit variable metabolic activity on ^18^F-FDG PET/CT, ranging from high to low uptake. In cases of low metabolic activity, ^18^F-FDG PET/CT may provide false-negative results, leading to underestimation of tumour burden.^4^ Somatostatin receptor scintigraphy using ^68^Ga-DOTA peptide PET is an established imaging modality for well-differentiated neuroendocrine tumours.^56^ Hemangiopericytomas are known to overexpress somatostatin receptors; however, the utility of ^68^Ga-DOTA peptide PET/CT in these tumours remains underexplored, particularly in cases with low ^18^F-FDG uptake.^7^ There is a paucity of studies, with only a few case reports demonstrating ^68^Ga-DOTA peptide uptake in these tumours.

This case highlights the potential of ^68^Ga-DOTATOC PET/CT in detecting hemangiopericytoma recurrence, especially when MRI accuracy is limited. This modality may aid in diagnosis, staging, treatment planning, and monitoring, potentially improving outcomes for these challenging vascular tumours. Additionally, it may serve as a gateway to potential ^177^Lu-DOTA peptide radionuclide therapy in cases with limited treatment options. Further research and clinical experience are required to fully elucidate the role of ^68^Ga-DOTATOC PET/CT in hemangiopericytoma management.

Authors' Contribution

Sharjeel Usmani: Conceptualization, Visualization, Writing – Original Draft, Writing – Review & Editing. Anjali Jain: Conceptualization, Writing – Review & Editing. Khulood Al Riyami: Investigation, Visualization. Syed Furqan Hashmi: Conceptualization, Writing – Original Draft, Writing – Review & Editing. Sofiullah Abubakar: Conceptualization, Visualization. Asiya Al Busaidi: Conceptualization, Visualization.

Ethics Statement

Written informed consent was obtained from the patient for publication of these images.