Extraosseous Ewing's sarcoma/primitive neuroectodermal tumor (ES/PNET) is an uncommon, aggressive, and malignant tumor with a poor patient outcome. Its occurrence in the lesser sac is a rare event and to the best of our knowledge, has not been previously described. The present case was clinically and radiologically misdiagnosed as a pancreatic tumor/gastrointestinal stromal tumor. Histopathology revealed a tumor with "small round cells" that were positive for CD99, confirming the diagnosis of ES/PNET. This report highlights the importance of considering Ewing's sarcoma in the differential diagnosis of intraabdominal, extraintestinal masses.
Antigens, CD/analysis ; Biopsy ; Cell Adhesion Molecules/analysis ; *Diagnostic Errors ; Female ; Humans ; Immunohistochemistry ; Middle Aged ; Neuroectodermal Tumors, Primitive, Peripheral/*diagnosis/immunology/pathology/therapy ; Pancreatic Neoplasms/*diagnosis ; Peritoneal Neoplasms/*diagnosis/immunology/pathology/therapy ; Predictive Value of Tests ; Sarcoma, Ewing/*diagnosis/immunology/pathology/therapy ; Tomography, X-Ray Computed ; Tumor Markers, Biological/analysis

Pancreatic endocrine tumours (PETs) are uncommon tumours with typical morphology characterised by relatively uniform cuboidal cells arranged in nests and festoons, with distinctive nuclear salt-and-pepper chromatin. A lipid-rich variant poses diagnostic difficulties in the midst of other pancreatic tumours and metastatic goblet cell carcinoid. A 22-year-old man presented with symptoms of abdominal pain and jaundice. His liver function test and blood glucose level were normal, but computed tomography of the abdomen suggested the presence of a tumour in the head of the pancreas. Specimen obtained by pancreaticoduodenectomy revealed an infiltrating yellow-tan tumour composed of nests and a cribriform arrangement of polygonal vacuolated cells with pyknotic nuclei, along with focal classical areas of PET. Two foci of early serous microcystic adenoma were seen. Immunohistochemistry contributed to the arrival of a conclusive diagnosis. Von Hippel-Lindau disease was excluded in our patient, as other supportive classical features of the syndrome were absent.
Adenoma ; Blood Glucose ; metabolism ; Carcinoid Tumor ; diagnosis ; pathology ; Humans ; Immunohistochemistry ; Lipids ; chemistry ; Male ; Neoplasm Metastasis ; Neuroendocrine Tumors ; diagnosis ; pathology ; Pancreatic Neoplasms ; diagnosis ; pathology ; Pancreaticoduodenectomy ; Young Adult

Introduction: This study provides a description of development of various components of the human ureter at different gestational ages. Methods:Measurements of the length of the ureter from pelvi-ureteric junction to vesico-ureteric junction, length of its intravesicular portion and angle made by the ureter at the entry into the bladder with respect to the internal ureteric orifice were taken. Transverse sections of the ureter were taken at the upper end, close to the pelvi-ureteric junction, and at the midpoint between the pelvis of the kidney and the vesico-ureteric junction. These were subjected for processing and stained with Haematoxylin Eosin and Masson’s Trichrome. They were then studied under the light microscope. Results: The length of the ureter from the pelvi-ureteric junction to the vesico-ureteric junction showed a highly positive correlation with the gestational age (GA). The angle of entry of the ureter to the bladder decreased as the GA increased. The microstructure of the ureter in both the sections showed development of transitional epithelium with an increase in layers by 33 weeks. At 18 weeks, the smooth muscle layer was in a single layer with an abundance of interspersed collagen fibers. By 33 weeks, the thickness of the wall increased significantly with a decrease in collagen. There was no trace of longitudinal muscle fibers even upto 33 weeks. Conclusion: Epithelial, muscular and connective tissue components displayed significant changes during intra uterine development.