RESUMO
BACKGROUND: Primary pancreatic paraganglioma is exceedingly rare. Most patients with pancreatic paraganglioma lack a typical clinical presentation, and the tumor is difficult to accurately differentiate from other pancreatic neuroendocrine tumors, making the misdiagnosis rate extremely high. Surgical excision is the primary treatment modality but is considered high risk. Because of its rich vascularity, the tumor easily bleeds during surgery, especially malignant paragangliomas invading large blood vessels. Thus, a thorough preoperative evaluation of the tumor is necessary. Here, we report a primary malignant pancreatic paraganglioma, the second such case in a young patient that was successfully resected surgically. CASE SUMMARY: A 26-year-old female patient was admitted to the hospital with unexplained abdominal pain. Dual-layer spectral-detector computed tomography (DLCT) revealed a mixed density mass in the pancreatic body and tail. The patient was transferred to our hospital after previous failed surgical resection at other hospitals. The patient and her family strongly desired surgery. After a thorough preoperative evaluation and adequate preparation, a large mass with the greatest dimension of 8.0 cm was successfully resected. The final pathological diagnosis was malignant paraganglioma. The patient was discharged in good condition 2 wk postoperatively. CONCLUSION: The rare malignant pancreatic paraganglioma reported here was difficult to diagnose preoperatively. Early filling of the draining vein may be a crucial diagnostic imaging feature. DLCT can provide more precise information for surgical resection through dual-energy imaging.
RESUMO
The polarization characteristics of Whispering-Gallery-Mode (WGM) fiber lasers based on evanescent-wave-coupled gain are investigated. For the laser gain is excited by side-pumping scheme, it is found that the polarization property of lasing emission is simply dependent on the polarized states of the pump beams. The polarization property of lasing emission depends on the propagating situation of the pump beams in an optical fiber if the laser gain is excited by evanescent-wave pumping scheme, that is, if the pump beams within the fiber are meridional beams, the lasing emission is a transverse electric (TE) wave that forms a special radial polarization emission. However, if the pump beams within the fiber are skew beams, both transverse magnetic (TM) and TE waves exist simultaneously in lasing emission that forms a special axially and radially mixed polarization emission. Pumped by skew beams, the wave-number differences between TE and TM waves are also investigated quantitatively, the results demonstrate that the wave-number difference decreases with the increase of the fiber diameter and the refractive index (RI) of the cladding solution. The observed polarization characteristics have been well explained based on lasing radiation mechanism of WGM fiber laser of gain coupled by evanescent wave.
