Table of ContentsDefinition / general | Essential features | Epidemiology | Sites | Clinical features | Laboratory | Prognostic factors | Gross description | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Electron microscopy description | Molecular / cytogenetics description | Molecular / cytogenetics images | Sample pathology report | Differential diagnosis | Board review style question #1 | Board review style answer #1 | Board review style question #2 | Board review style answer #2
Cite this page: Yavas A, Basturk O. Sclerosing epithelioid mesenchymal neoplasm. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/pancreassclerosingepit.html. Accessed August 2nd, 2021.
Definition / general
- Well circumscribed tumor with a geographic pattern of epithelioid cell nests alternating with spindle cell fascicles
- Vimentin (diffuse), CD99 (diffuse) and cytokeratin (AE1 / AE3 and CK18, dot-like) expression
- Lack of abnormalities in any of key genetic drivers
- Mesenchymal transcriptomic features and distinct methylation signature
- Mostly occurs in head and neck of the pancreas (Mod Pathol 2020;33:456)
- Nonspecific symptoms
- Serum tumor markers (CA19.9 and CEA) within normal limits
- None known; exhibits indolent behavior (Mod Pathol 2020;33:456)
- Well circumscribed and solid, usually confined to the pancreatic parenchyma
- White-tan and firm cut surface
- Median tumor size: 1.8 cm (Mod Pathol 2020;33:456)
Microscopic (histologic) description
- Solid neoplasms associated with extensive fibrosis and dense lymphoid aggregates at the periphery (Mod Pathol 2020;33:456)
- Entrapped pancreatic parenchyma may be seen at the periphery or within the tumor
- Density of tumor cells varies significantly, not only among tumors but also throughout each tumor, creating a geographic appearance of hypercellular and hypocellular areas with collagenous stroma
- No true epithelial structures such as glands, papillae or pseudopapillae (Mod Pathol 2020;33:456)
- Most cells are epithelioid to spindled with scant cytoplasm and round to oval nuclei with open chromatin
- Others display more irregular, hyperchromatic nuclei
- Occasional mitotic figures may be seen
Microscopic (histologic) images
Contributed by Olca Basturk, M.D.
Electron microscopy description
- Nonspecific findings; occasional desmosomes, perinuclear tonofilaments and abundant rough endoplasmic reticulum (Mod Pathol 2020;33:456)
Molecular / cytogenetics description
- No recurrent somatic mutations, amplifications or deletions in any known oncogenes or suppressor genes (Mod Pathol 2020;33:456)
- Activation or enrichment of pathways related to the extracellular matrix, tight junctions, adherens junctions and TGFβ signaling by Gene Set Enrichment Analysis (Mod Pathol 2020;33:456)
- A unique cluster by unsupervised analysis of the methylation profiles (Mod Pathol 2020;33:456)
Molecular / cytogenetics images
Sample pathology report
- Pancreas and duodenum, pancreaticoduodenectomy:
- Sclerosing epithelioid mesenchymal neoplasm (see comment)
- Comment: The tumor is confined to the pancreatic parenchyma and measures 2.2 cm in greatest dimension. Adjacent pancreas reveals atrophy. Surgical margins are free of tumor. 16 benign lymph nodes are identified (0/16).
- Solid pseudopapillary neoplasm:
- Sarcomatoid carcinoma:
- Larger infiltrative tumors with considerable pleomorphism, necrosis and proliferative activity
- Glandular component may be present
- KRAS, TP53, SMAD4, CDKN2A mutations
- Sclerosing epithelioid fibrosarcoma:
- MUC4 expression
- EWSR1-CREB3L1, FUS-CREB3L21 or FUS-CREB3L2 fusions
- Solitary fibrous tumor:
- Inflammatory myofibroblastic tumor:
- Perivascular epithelioid cell neoplasm (PEComa):
- Gastrointestinal stromal tumor:
Board review style question #1
Board review style answer #1
Board review style question #2
Which one of the following microscopic features is seen in sclerosing epithelioid mesenchymal neoplasms of the pancreas?
- No entrapped pancreatic parenchyma is seen within the tumors.
- They are composed of epithelioid cells only.
- They are predominantly hypocellular tumors.
- They have well circumscribed borders.
- True epithelial structures such as glands, papillae and pseudopapillae are common.