Malignant gastrointestinal neuroectodermal tumor: a case report and review of the literature.
BACKGROUND
Malignant gastrointestinal neuroectodermal tumor (GNET) is an extremely rare entity that was first described by Zambrano et al. in 2003 as "Clear cell sarcoma-like tumor of the gastrointestinal tract". It shares some of the histological features of clear cell sarcoma (CCS) but lacks the immunohistochemical reactivity for melanocytic markers. We report a case of GNET that was initially misdiagnosed as gastrointestinal stromal tumor (GIST). Recognizing this entity is important to avoid misdiagnosis.


METHODS
A case of an 18-year-old male presented with a small intestinal tumor. Histologically it was characterized by polygonal cells arranged in pseudoalveolar pattern and situated in the muscularis propria. Scattered osteoclast-like multinucleated giant cells were also noted. The neoplastic cells were positive for S-100 protein and negative for HMB-45, Melan A, smooth muscle actin, desmin and CD117. EWSR1 gene rearrangement was detected by fluorescence in situ hybridization (FISH) analysis. The patient returned with recurrence after 36 months' management by surgical resection and died one year later.


CONCLUSIONS
GNET can be mistaken histologically for other non-epithelial gastrointestinal tumors. Awareness of its existence and diagnostic criteria by the pathologist is necessary to avoid misdiagnosis, particularly as GIST, CCS or malignant peripheral nerve sheath tumor (MPNST).
Department of Pathology and Laboratory Medicine, King Fahd Hospital of University, College of Medicine, University of Dammam, Dammam, Saudi Arabia. malyousef@uod.edu.sa.
Mohammed J
MJ
Alyousef
Department of Pathology and Laboratory Medicine, King Fahd Hospital of University, College of Medicine, University of Dammam, Dammam, Saudi Arabia.
Jumana A
JA
Alratroot
Department of Pathology and Laboratory Medicine, King Fahd Hospital of University, College of Medicine, University of Dammam, Dammam, Saudi Arabia.
Tarek
T
ElSharkawy
Department of Pathology and Laboratory Medicine, King Fahd Hospital of University, College of Medicine, University of Dammam, Dammam, Saudi Arabia.
Mohamed A
MA
Shawarby
Department of Pathology and Laboratory Medicine, King Fahd Hospital of University, College of Medicine, University of Dammam, Dammam, Saudi Arabia.
Mohammad A
MA
Al Hamad
Department of Pathology and Laboratory Medicine, King Fahd Hospital of University, College of Medicine, University of Dammam, Dammam, Saudi Arabia.
Tarek M
TM
Hashem
Department of Pathology and Laboratory Medicine, King Fahd Hospital of University, College of Medicine, University of Dammam, Dammam, Saudi Arabia.
Ahmed
A
Alsayyah
D000293:Adolescent; D014408:Biomarkers, Tumor / Q000032:analysis / Q000235:genetics; D001706:Biopsy; D002148:Calmodulin-Binding Proteins / Q000235:genetics; D003951:Diagnostic Errors; D017809:Fatal Outcome; D046152:Gastrointestinal Stromal Tumors / Q000737:chemistry / Q000235:genetics / Q000473:pathology*; D015321:Gene Rearrangement; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D007580:Jejunal Neoplasms / Q000737:chemistry / Q000235:genetics / Q000473:pathology* / Q000601:surgery; D008297:Male; D009364:Neoplasm Recurrence, Local; D017599:Neuroectodermal Tumors / Q000737:chemistry / Q000235:genetics / Q000473:pathology* / Q000601:surgery; D011237:Predictive Value of Tests; D034802:RNA-Binding Protein EWS; D016601:RNA-Binding Proteins / Q000235:genetics; D013997:Time Factors; D016896:Treatment Outcome
D014408:Biomarkers, Tumor; D002148:Calmodulin-Binding Proteins; C500986:EWSR1 protein, human; D034802:RNA-Binding Protein EWS; D016601:RNA-Binding Proteins
Clear cell sarcoma-like tumor of gastrointestinal tract; EWSR1; Malignant gastrointestinal neuroectodermal tumor