Paola López, MD, Victor Torres, MD Hospital Damas, Ponce, Puerto Rico
Introduction: Solitary fibrous tumors and hemangiopericytomas (SFT/HPC) are rare mesenchymal neoplasms that were thought to be different identities but during recent years it was found that both share the same etiology. SFT/HPC’s tumors are uncommon and less than 30% of cases develop metastatic disease. In this report we describe a case of brain SFT/HPC with metastases to pancreas diagnosed using endoscopic ultrasound guided fine needle aspiration (EUS-FNA).
Case Description/Methods: 61 year old Female diagnosed in 2001 with CNS SFT/HPC tumor WHO grade 3. She underwent four brain surgeries for removal of tumors with last excision taking place in 2016. Also received gamma knife therapy to control tumor growth but in 2017 she was found with recurrence,and was then started on bevacizumab therapy.One year later, she started to complain of abdominal pain.Physical examination was unrevealing.Her laboratory work up including cell blood count, complete metabolic panel, pancreatic enzymes and CA 19-9 level were unremarkable. She did not have any history of pancreatic disorders. Abdominal enhanced CT scan showed large heterogeneously enhancing mass in the pancreatic body with low density areas suggestive of necrosis measuring 7.8 cm x 6.7 cm.For further assessment, patient underwent EUS- guided FNA using a 22 gauge Expect™ needle.Pathology description showed a paucicellular sample with pattern less pattern of cells separated by thick collagenous material. Immunohistochemistry (IHC) revealed a positive result for CD34 and STAT6.These results were consistent with previous brain histological and IHC results confirming metastatic disease to pancreas. After diagnosis, a PET/CT scan demonstrated an area of 7.3 x 7.0 x 7.1cm moderately hypermetabolic mass of pancreatic body with SUV max of 7.91. There was no evidence of other organ involvement. Since the disease was limited to the pancreas, she underwent distal pancreatectomy. The margins of resection were negative for neoplasia.She made an uneventful recovery and currently continues with imaging and clinical surveillance.
Discussion: SFT/HPC are tumors caused by a fusion genes between NGF1-A binding protein 2 and signal transducer and activator of transcription 6 (STAT6) that causes expression and accumulation of STAT6 protein in the cell nuclei. These neoplasms typically metastatize in the liver, pleura and bone.Malignancy depends on mitiotic activity and other markers.However, the majority has unpredictable behavior and recurrency is common,even those with benign features.
Figure: A and B. EUS findings show a heterogeneous well-defined lesion abutting the pancreas body without vessel involvement or peripancreatic lymphadenopathy. C. Hematoxylin and eosin stain of pancreatic mass showing paucicellular sample with patternless pattern of cells separated by thick collagenous material, (D) CD34 immunohistochemical stain and (F) nuclear expression of STAT6 on immunohistochemical stain of cell block specimens. PET-CT scan images in coronal (G) and sagittal view (H) showing a 7.3 x 7.0 x 7.1 cm moderately hypermetabolic mass in the body of the pancreas, abutting the greater curvature of the stomach, with SUV max of 7.91. The rest of the abdomen and pelvis show physiologic FDG metabolism.
Paola López indicated no relevant financial relationships.
Victor Torres indicated no relevant financial relationships.
Paola López, MD, Victor Torres, MD. P2150 - Solitary Fibrous Tumor: A Rare Cause of Pancreatic Mass Diagnosed by Endoscopic Ultrasound, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.