Gastroblastoma

Definition

A proposed rare epithelio-mesenchymal biphasic neoplasms of the stomach.

Epidemiology

This is a tumour of young adults.

Macroscopic appearances

The tumour is multinodular or lobulated and may be polypoidal.  

Histopathology

There is a dominant spindle cell component.  The cells have pale to clear cytoplasm and blunt-ended nuclei, showing mild pleomorphism.  There are focal epithelioid clusters within which there may be formation of lumina .  The two components blend.   The mitotic rate is variable.

Immunohistochemistry

FISH

None of three cases demonstrated SS18 gene rearrangement by FISH.

Differential diagnosis

• Carcinosarcoma / sarcomatoid carcinoma: occurs in older patients; shows marked atypia and necrosis; often has a squamous component
• Synovial sarcoma: shows sharp demarcation of the two components; these is a SS18 gene rearrangement.
• Teratoma: occurs in infants; shows multiple lines of differentiation
• Myoepithelioma of skin/salivary gland type has not been reported in the stomach: dominated by the epithelial component and cytokeratin positivity in both components; positive for SMA and S100.
• ‘‘adenoleiomyosarcoma,’’, a biphasic tumour with carcinomatous and leiomyosarcomatous elements

Prognosis

On limited experience, the prognosis is good.

References

1 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.

This page last revised 2.10.2009

©SMUHT/PW Bishop