Background
Solitary fibrous tumors (SFTs) are rare tumors, mostly derived from connective tissue mesenchymal cells that arise from the pleura. There are very few reports of primary pancreatic SFT. Preoperative diagnosis is difficult owing to the lack of distinctive radiological findings. We report a case of pancreatic SFT with particularly rare malignant findings.
Case presentation
A 60-year-old man was referred to the hospital because of a right upper quadrant mass and abnormal liver function test results. Contrast-enhanced computed tomography (CT) showed a well-defined enhanced tumor measuring approximately 8 cm in the pancreatic head. Magnetic resonance imaging (MRI) showed T1WI hypointensity, T2WI hyperintensity, and DWI hyperintensity. The main pancreatic duct and common bile duct were dilated owing to obstruction by the tumor. The following tumor markers were mildly elevated: carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA19-9), SPan-1, and DUPAN-2. The histological diagnosis obtained by endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) was negative for pancreatic ductal carcinoma, malignant lymphoma and neuroendocrine tumor, suggesting the possibility of mesenchymal tumor, but the diagnosis was not confirmed. The patient was judged suitable for surgery and underwent subtotal stomach-preserving pancreatoduodenectomy with D2 lymph node dissection. On histopathological examination of the resected specimen, infiltrating spindle-shaped cells had proliferated, containing numerous mitotic figures, with necrotic findings inside the tumor. Immunostaining was positive for cluster of differentiation-34 (CD34), B cell CLL/lymphoma-2 (Bcl-2), and signal transducer and activator of transcription (STAT6). On the basis of these findings, a diagnosis of malignant pancreatic SFT was made. The patient remains free of recurrent disease after 12 months of follow-up without adjuvant therapy and he is being carefully followed up as an outpatient.
Conclusions
We experienced a case of malignant pancreatic head SFT. Immunohistochemical staining of the extracted specimens was useful for diagnosis.
Beckwith-Wiedemann syndrome (BWS) is the most common congenital overgrowth syndrome involving tumor predisposition. BWS is caused by various epigenetic or genetic alterations that disrupt the imprinted genes on chromosome 11p15.5 and the clinical findings of BWS are highly variable. Hyperinsulinemic hypoglycemia is reported in about half of all babies with BWS. We identified an infant with diazoxide-unresponsive congenital hyperinsulinism (HI) without any apparent clinical features suggestive of BWS, but diagnosed BWS by molecular testing. The patient developed severe hyperinsulinemic hypoglycemia within a few hours after birth, with macrosomia and mild hydronephrosis. We excluded mutations in the K(ATP) channel genes on chromosome 11p15.1, but found a rare homozygous single nucleotide polymorphism (SNP) of ABCC8. Parental SNP pattern suggested paternal uniparetal disomy in this region. By microsatellite marker analysis on chromosome 11p15, we could diagnose BWS due to the mosaic of paternal uniparental disomy. Our case suggests that some HI of unknown genetic etiology could involve undiagnosed BWS with no apparent clinical features, which might be diagnosed only by molecular testing.
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