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Digestive PEComas: a solution when the diagnosis fails to "fit"
Muriel Genevay1, Thomas Mc Kee, George Zimmer
1Institut Universitaire de Pathologie, Lausanne, Switzerland. muriel.genevay@hcuge.ch
Annals of Diagnostic Pathology
|December 23, 2004
Summary
This study presents two rare cases of perivascular epithelioid cell tumors (PEComas) in the digestive tract. Diagnosis was confirmed through morphology and immunohistochemistry, highlighting key differential diagnoses for these intra-abdominal tumors.
Area of Science:
- Gastroenterology
- Oncology
- Pathology
Background:
- Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal neoplasms.
- Digestive and intra-abdominal PEComas are exceptionally uncommon, posing diagnostic challenges.
Observation:
- Two cases of intra-abdominal PEComas are described: one in the caecum of a 36-year-old woman and another in the pararectal region of a 35-year-old woman.
- Histological examination revealed distinct cellular morphologies, with one tumor composed of spindle cells and the other of epithelioid cells.
- Immunohistochemical analysis showed tumor cell expression of smooth muscle actin and melanocyte markers (HMB45), with negative staining for S-100 protein and CD117.
Findings:
- The morphological and immunohistochemical features supported the diagnosis of PEComa in both cases.
- Key differential diagnoses in the gastrointestinal tract include gastrointestinal stromal tumors (GISTs), particularly epithelioid subtypes, and metastatic carcinomas or melanomas.
- Other considerations include rhabdomyosarcoma, paraganglioma, leiomyosarcoma, and clear cell sarcoma.
Implications:
- Accurate diagnosis of digestive PEComas relies on a combination of histomorphology and specific immunohistochemical markers.
- Distinguishing PEComas from other intra-abdominal tumors like GISTs and metastases is crucial for appropriate patient management.
- Further research into the pathogenesis and optimal treatment strategies for digestive PEComas is warranted.