Definition
Biphasic epithelial-mesenchymal tumor of the stomach
Diagnostic Criteria
One report of three cases to date (Miettinen)
One additional case report (Shin)
Two components: mesenchymal and epithelial
May be sharply or indistinctly demarcated
Diffuse sheets of uniform oval to spindled cells
Clusters and cords of epithelioid cells
Occasional small gland formation by epithelioid cells in a field of spindled cells
Mitotic rates observed: 0, 0, 4, 30 / 50 hpf
All cases to date in young adults and one 9 year old Robert V Rouse MD
Original posting/updates: 2/4/10, 11/27/11
Supplemental studies
Immunohistology
Epithelioid cells
Positive for keratins AE1/3, CK18, focally for CK7
Negative for CK5/6, CK20, EMA
Spindle cells CD10 strong positive
Both populations negative for: CD34, CD99, ER, CKIT, Smooth muscle actin, Desmin, S100, p63, Calretinin, Chromogranin, Synaptophpysin, CDx2 and TTF1
(One case report of CD56 and CKIT positive epithelioid cells with only focal CD10 staining of stroma)
Genetic Studies
FISH negative for SS18 (marker of synovial sarcoma)
Differential Diagnosis
Gastroblastoma Carcinosarcoma
Young adults
Generally older patients
Cytologically bland
Malignant epithelial and stromal elements
Gastroblastoma Gastric Synovial Sarcoma
Components may be indistinct
Components generally distinct
FISH negative for SS18 abnormalities
FISH shows evidence of SS18 rearrangement
Gastroblastoma Gastric Teratoma
Young adults
Generally infants
Only two components
Multiple tissue types
Gastroblastoma Mesothelioma
Negative for CK5/6 and calretinin
CK5/6 and calretinin positive
Not serosal based
Based in serosa
Clinical
All cases ≤30 to date
All alive without disease
Bibliography
Miettinen M, Dow N, Lasota J, Sobin LH. A distinctive novel epitheliomesenchymal biphasic tumor of the stomach in young adults ("gastroblastoma"): a series of 3 cases. Am J Surg Pathol. 2009 Sep;33(9):1370-7.
Shin DH, Lee JH, Kang HJ, Choi KU, Kim JY, Park do Y, Lee CH, Sol MY, Park JH, Kim HY, Montgomery E. Novel epitheliomesenchymal biphasic stomach tumour (gastroblastoma) in a 9-year-old: morphological, ultrastructural and immunohistochemical findings. J Clin Pathol. 2010 Mar;63(3):270-4.
