Gastroblastoma in old age

Gastroblastoma is a rare, distinctive gastric biphasic tumour affecting both sexes, with metastatic potential. To the best of our knowledge, 11 cases have been published so far, solidly supported by morphology, immunophenotype, and, in four instances, by identification of a characteristic MALAT–GLI1 fusion gene.1-6 A twelfth ‘gastroblastoma’, questionable because of the presence of cellular atypia significantly deviating from previous canonical examples, has been reported.7 A gastroblastoma‐like duodenal neoplasm has also been described.8 Finally, a series of six extragastric tumours harbouring GLI1 rearrangements has been published, showing focal cytokeratin positivity and scattered tubular structures in one case (bearing an ACTB–GLI1 fusion), leading to the proposal of an entity defined as ‘malignant epithelioid neoplasm with GLI1 fusions’.9 All reported canonical gastroblastomas occurred within the third decade of life, except for one in a patient aged 56 years. Grossly, gastroblastomas form multinodular/lobulated, often partly cystic/haemorrhagic, masses involving the gastric wall layers. Histologically, these tumours are biphasic, featuring spindle‐cell and epithelioid components, immature but non‐pleomorphic, with low mitotic activity. On immunohistochemistry, gastroblastoma variously expresses CD10, vimentin and cytokeratins, the former two prevailing in the spindle cells, and the latter prevailing in the epithelioid cells. The recently reported consistent finding of a MALAT1–GLI1 fusion gene in gastroblastoma allows a solid differential diagnosis with other biphasic neoplasms such as synovial sarcoma, carcinosarcoma, and teratoma. Intriguingly, the same genetic defect has been detected in some plexiform fibromyxomas, which are gastric mesenchymal tumours that are definitely benign, lack biphasic morphology and are most likely unrelated to gastroblastoma.6, 9 Table 1 summarises the features of the gastroblastomas published so far. Herein, we report a gastric antral tumour with morphological, immunophenotypic and genotypic features consistent with gastroblastoma in a 79‐year‐old male.