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Ewing's sarcoma of the lesser sac masquerading as a pancreatic tumor.

Rao L, Monappa V, Rodrigues G, Suresh BP - Korean J. Intern. Med. (2012)

Bottom Line: 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.This report highlights the importance of considering Ewing's sarcoma in the differential diagnosis of intraabdominal, extraintestinal masses.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Kasturba Medical College, Karnataka, India.

ABSTRACT
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.

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Section shows sheets of small round tumor cells with a rim of clear cytoplasm (H&E, × 400).
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Figure 4: Section shows sheets of small round tumor cells with a rim of clear cytoplasm (H&E, × 400).

Mentions: Microscopy revealed a fairly well-circumscribed tumor with a fibrous pseudocapsule composed of sheets of small round cells with enlarged round to oval nuclei, fine stippled chromatin, and moderately clear to amphophilic cytoplasm, which was periodic acid-Schiff stain positive. Geographic areas of necrosis with focal peritheliomatous proliferation of tumor cells around the blood vessels, increased mitosis, prominent apoptosis, and nuclear moulding were noted. In some areas, tumor islands were surrounded by desmoplastic stroma. Peripherally compressed pancreatic tissue was seen and no tumor infiltration was discerned (Figs. 3 and 4). The tumor cells were CD99 positive, while cytokeratin (CK), desmin, synaptophysin (SYP), and chromogranin (CHR) were negative (Fig. 5). Based on morphology and immunohistochemistry findings, a final diagnosis of extraosseous Ewing's sarcoma/primitive neuroectodermal tumor (ES/PNET) of the lesser sac was made.


Ewing's sarcoma of the lesser sac masquerading as a pancreatic tumor.

Rao L, Monappa V, Rodrigues G, Suresh BP - Korean J. Intern. Med. (2012)

Section shows sheets of small round tumor cells with a rim of clear cytoplasm (H&E, × 400).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3295994&req=5

Figure 4: Section shows sheets of small round tumor cells with a rim of clear cytoplasm (H&E, × 400).
Mentions: Microscopy revealed a fairly well-circumscribed tumor with a fibrous pseudocapsule composed of sheets of small round cells with enlarged round to oval nuclei, fine stippled chromatin, and moderately clear to amphophilic cytoplasm, which was periodic acid-Schiff stain positive. Geographic areas of necrosis with focal peritheliomatous proliferation of tumor cells around the blood vessels, increased mitosis, prominent apoptosis, and nuclear moulding were noted. In some areas, tumor islands were surrounded by desmoplastic stroma. Peripherally compressed pancreatic tissue was seen and no tumor infiltration was discerned (Figs. 3 and 4). The tumor cells were CD99 positive, while cytokeratin (CK), desmin, synaptophysin (SYP), and chromogranin (CHR) were negative (Fig. 5). Based on morphology and immunohistochemistry findings, a final diagnosis of extraosseous Ewing's sarcoma/primitive neuroectodermal tumor (ES/PNET) of the lesser sac was made.

Bottom Line: 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.This report highlights the importance of considering Ewing's sarcoma in the differential diagnosis of intraabdominal, extraintestinal masses.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Kasturba Medical College, Karnataka, India.

ABSTRACT
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.

Show MeSH
Related in: MedlinePlus