Solitary Fibrous Tumor of the Prostate Shown on FAPI PET/CT : Clinical Nuclear Medicine

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Solitary Fibrous Tumor of the Prostate Shown on FAPI PET/CT

Yang, Tianshuo MM; Zhu, Ronghua MM; Guo, Zhongying MD; Niu, Xiaobing MD; Tao, Weijing MD

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Clinical Nuclear Medicine 48(6):p 530-531, June 2023. | DOI: 10.1097/RLU.0000000000004635
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A 57-year-old man was admitted to our hospital because of increased frequency of micturition and urinary urgency. Ultrasonographic examination revealed a cystic solid nodule in the prostate. We then performed MRI to determine whether the nodule was prostatic cancer. T2-weighted imaging showed a cystic solid nodule in the right side of the transition zone of the prostate (A, arrow). The solid nodule had a slightly high signal intensity on diffusion-weighted imaging (B, arrow), a reduced apparent diffusion coefficient value (C, arrow), and abnormal moderate enhancement on an enhanced scan (D, arrow). According to the Prostate Imaging Reporting and Data System (PI-RADS) Version 2.1,1 the lesion had a PI-RADS score of 5. A prostate biopsy revealed diffuse infiltration of small round cells in the prostate tissue (E, hematoxylin-eosin stain, ×200). Combined with the immunohistochemical results of CD34 positivity (F, ×200) and STAT6 positivity (G, ×400), the patient was diagnosed with a solitary fibrous tumor.2,3 The Ki67 expression of the lesion was approximately 1% (H, ×200).
We performed FDG PET/CT to detect any systemic metastases or other primary lesions. Surprisingly, the primary prostatic lesion showed low FDG uptake on the MIP image (A, arrow). Similarly, on the axial PET (B, arrow) and corresponding PET/CT images (C, arrow), the lesion showed mild FDG uptake with an SUVmax of 2.804. The patient was enrolled in an ongoing clinical trial (YX-2021-113-01), which was approved by the institutional review board of our hospital. This clinical trial was a prospective study of FAPI PET/CT in baseline assessment and efficacy evaluation of various tumors, chronic inflammation, and myocardial infarction. After obtaining informed consent from the patient, we performed a FAPI PET/CT examination 2 days later. There was significant uptake of FAPI in the prostate on the MIP image (F, arrow), without other abnormal activity elsewhere. Axial PET (D, arrow) and corresponding PET/CT fusion images (E, arrow) showed high FAPI accumulation with an SUVmax of 24.423 in the prostatic lesion. Solitary fibrous tumors are morphologically diverse fibroblast tumors associated with high risks of metastasis and death.4,5 Solitary fibrous tumors can show aggressive behavior, even in the absence of any morphologic evidence of malignancy at onset.6 Furthermore, solitary fibrous tumors that initially have benign histopathologic features can occasionally metastasize.7,8 FAPI PET/CT might have the potential to be used as a complementary imaging modality to identify solitary fibrous tumors.


1. Turkbey B, Rosenkrantz AB, Haider MA, et al. Prostate Imaging Reporting and Data System Version 2.1: 2019 Update of Prostate Imaging Reporting and Data System Version 2. Eur Urol. 2019;76:340–351.
2. Tanaka K, Kishimoto T, Ohtsuka M, et al. Importance of NAB2-STAT6 fusion in the diagnosis of pancreatic solitary fibrous tumor with hamartoma-like features: a case report and review of the literature. Case Rep Pathol. 2015;2015:149606.
3. Zhang A, Zhang H, Zhou X, et al. Solitary fibrous tumors of the pleura shown on 18F-FDG and 68Ga-DOTA-FAPI-04 PET/CT. Clin Nucl Med. 2021;46:e534–e537.
4. Davanzo B, Emerson RE, Lisy M, et al. Solitary fibrous tumor. Transl Gastroenterol Hepatol. 2018;3:94.
5. Martin-Broto J, Mondaza-Hernandez JL, Moura DS, et al. A comprehensive review on solitary fibrous tumor: new insights for new horizons. Cancers (Basel). 2021;13:2913.
6. Hassani M, Jung S, Garzia L, et al. Aggressive behavior predictors in solitary fibrous tumor: demographic, clinical, and histopathologic characteristics of 81 cases. Ann Surg Oncol. 2021;28:6861–6867.
7. Demicco EG, Park MS, Araujo DM, et al. Solitary fibrous tumor: a clinicopathological study of 110 cases and proposed risk assessment model. Mod Pathol. 2012;25:1298–1306.
8. Goker F, Mazzucato C, Maggioni M, et al. Solitary fibrous tumor of parotid gland: a case report and short review of literature. Eur Rev Med Pharmacol Sci. 2022;26:45–50.

FAPI; FDG; PET/CT; MRI; solitary fibrous tumors

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