Utility of 18F-FDG PET/CT in Hemangiopericytoma

Introduction: Hemangiopericytomas (HPC) are rare tumor (0.060 per 100,000 individuals) involving blood vessels and soft tissues, originating anywhere in the body along the blood capillaries, however the most common locations reported are brain, lower extremities, pelvic area, head, and neck. This entity can either be benign or malignant, with the latter showing metastases primarily to the lungs and bones. They also have high incidence of local recurrence and distant metastases. Currently 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) imaging is the standard of care for staging and restaging for various malignancies but there is very little information about its application in HPC. This study with limited patients is conducted to give an insight into this scenario.

Methods: We retrospectively evaluated clinical and imaging data of 6 HPC patients who underwent 18F-FDG PET/CT for staging and restaging, during the period from January 2017 to December 2021. All the 6 PETCT scans were analysed for primary tumor site and the purpose of visit (staging /restaging). The maximum standardized uptake value (SUV max) of the primary lesion and background was calculated.

Results: Total 6 patients (5 males and 1 female and, M:F=5:1) with median age of 28 years (range- 6 to 46 years) were included in the study. The primary sites of involvement were brain (4/6), pelvis (1/6) and tibia (1/6) in these patients with metastasis noted to lymph node in only 1 patient. The mean SUVmax of the primary tumors was 8.77±3.21 and the background was 3.24±1.25. Three patients underwent scan for baseline staging while the remaining for restaging purpose. There was a significant difference detected between the mean SUV max of primary lesions and the background with a p value of 0.047(<0.05, paired student T test).

Conclusions: 18F-FDG PET/CT can be used for staging and restaging purpose in HPCs thus helping in the management of the disease. Additionally, parameters like SUVmax assessed on 18F-FDG PET/CT can give semiquantitative assessment of the lesions.