68Ga DOTATATE PET/CT Imaging of a Solitary Fibrous Tumor of the Nasopharynx

68Ga-DOTATATE PET/CT Imaging of a Solitary Nasopharyngeal Metastasis of Merkel Cell Carcinoma

ABSTRACT

Merkel cell carcinoma (MCC) is an uncommon highly aggressive cutaneous neuroendocrine neoplasm with high mortality. Rarer still is nasopharyngeal metastasis of MCC. Herein, we report the 68Ga-DOTATATE PET/CT findings of MCC with metastasis to the nasopharynx in a 53-year-old man who underwent surgery for MCC in his thigh 2 years ago.

68 Ga-DOTATOC PET/CT Imaging of a Muscular Solitary Fibrous Tumor

ABSTRACT

A 73-year-old woman was referred for 68 Ga-DOTATOC PET/CT staging of a grade 2 pancreatic neuroendocrine tumor, which showed the primary pancreatic tumor, liver metastases, one left pleural metastasis, and high uptake in a mass of the right triceps brachii muscle. Two years before, she underwent 18 F-FDG PET/CT and 111 In-pentetreotide scan, respectively, with low and high uptake of each radiotracer in the triceps mass. Histopathological analysis revealed a solitary fibrous tumor. Immunohistochemistry showed no staining for SSTR-2 and SSTR-5, suggesting tumor overexpression of another somatostatin receptor. This case highlighted a potential pitfall on 68 Ga-DOTATOC PET/CT.

Abdominopelvic Hemangiopericytoma Mimicking Neuroendocrine Tumor on 68 Ga-DOTANOC PET/CT

ABSTRACT

We present the case of a 60-year-old man who was being evaluated for 2 intra-abdominal masses. The masses were tracer avid on 68 Ga-DOTANOC PET/CT and were suggestive of neuroendocrine tumor. Histopathology, however, confirmed the masses to be hemangiopericytoma. Hemangiopericytoma comes under the umbrella of solitary fibrous tumors, a rare tumor group arising from the mesenchymal cells. Solitary fibrous tumors commonly arise from the pleura but can occur anywhere in the body. Intra-abdominal hemangiopericytoma are extremely rare and should be kept in mind as one of the differential diagnoses for 68 Ga-DOTA peptide-avid tumors.

68 Ga-PSMA-Avid Intranasal Solitary Fibrous Tumor

ABSTRACT

The utility of molecular imaging in solitary fibrous tumors has not been fully established. We present a rare case of recurrent intranasal solitary fibrous tumor incidentally localized on 68 Ga-PSMA PET/CT scan, which turned out to be metabolically inactive on 18 F-FDG PET/CT.

A Rare Case of Metastatic Solitary Fibrous Tumor (Hemangiopericytoma) of the Dura on 18F-FDG PET/CT

ABSTRACT

Solitary fibrous tumor is a rare neoplasm of mesenchymal origin. It can arise in various locations, most commonly in the pleura. It encompasses a heterogeneous group of histological patterns with different biological behavior. In some cases, metastases occur, sometimes years after the initial diagnosis. We report a case of metastatic meningeal hemangiopericytoma, also called solitary fibrous tumor of the dura, exhibiting liver metastases and muscle metastases 5 years after resection and adjuvant radiotherapy of the primary tumor.

68Ga-DOTATOC PET/CT in Pleural Solitary Fibrous Tumors

ABSTRACT

Solitary fibrous tumor of the pleura (SFTP) is a rare mesenchymal neoplasm. Preoperative diagnosis is usually difficult and based on radiological findings only. We report the imaging results observed in 5 patients with SFTP (2 malignant) obtained by 68Ga-DOTATOC PET/CT. At qualitative analysis, all tumors showed uptake of 68Ga-DOTATOC. Mean tumor SUVmax was 9.9 ± 5.7. The expression of SST2 (somatostatin receptors subtype 2) was confirmed by immunohistochemistry in 2 tumor samples, and by gene amplification of SST2 mRNA in all cases. These data suggest a diagnostic role of radioreceptor PET/CT in SFTP, and open novel potential treatment options in unresectable/metastatic disease.

Giant Cell-Rich Solitary Fibrous Tumor in the Nasopharynx: Case Report and Literature Review

Solitary fibrous tumors (SFTs) can occur in several locations outside the pleura, but rarely in the sinonasal tract, and particularly not in the nasopharynx. Herein, we describe an unusual case of giant cell-rich SFT (GCRSFT) occurring in the nasopharynx. A 64-year-old man experienced dizziness and headache for more than 10 years with no obvious cause. Computed tomography (CT) scan showed a 3.9 cm × 2 cm tumor on the posterior lateral wall of the left nasopharynx, and angiography revealed a hypervascular tumor fed by branches of the left carotid artery. Hence, preoperative embolization was performed, and then the tumor was endoscopically resected. The symptoms were relieved after the resection, and postoperative head CT and video laryngoscopy showed that the tumor was completely resected. We next characterized the specific pathological characteristics of the resected tumor. Histologically, the tumor was characterized by varying cellular proliferation of cytologically bland spindle cells within a collagenous stroma, with prominent interspersed branching vessels. Mitotic activity was low (2/50HPF), and there was no evidence of pleomorphism or tumor necrosis. Moreover, multinucleated giant cells with deep nuclear staining and distributed in pseudovascular spaces were found within the tumor. We ruled out the possibility that our case was giant cell fibroblastoma (GCF) by immunohistochemical analysis, showing that the tumor cells were positive for CD34, CD99, STAT6, and BCL-2, and that the Ki-67 labeling index was 3%, indicating that our case was SFT and not GCF. The patient's condition is generally good after a 14-month follow-up. This report serves to broaden the morphologic spectrum of GCRSFT and will help clinicians and pathologists better understand this entity to prevent misdiagnosis.