One finding and two surprises

Correct answer: e.

Discussion

This is a somewhat peculiar looking gastric lesion that is composed of a pale part and more erythematous, indurated part. The lesion is clearly malignant and has an ominous-looking nodularity in the centre and a more infiltrative edge.

The pale part of the lesion corresponded to the poorly differentiated part of this gastric cancer, whilst the moderately differentiated part of the cancer corresponded to the more erythematous part.

The photographs below show the histological findings for the lesion and reveal something unexpected.

Correct answer: d.

Discussion

The dark purple, angular cell clusters indicate the poorly differentiated adenocarcinoma. In the bottom images several more round and purple deposits are seen that are composed of large dark cells. These cells are neuroendocrine cells. Mixed adenoneuroendocrine carcinoma (MANEC) is a rare gastrointestinal tumour that consists of both an adenocarcinomatous component and a neuroendocrine component that comprises at least 30% of the tumour.  Prior to the introduction of the term mixed adenoneuroendocrine carcinoma in 2010, these lesions were reported as a mixed or composite tumour.¹

This kind of neoplasm is aggressive and usually has a poor prognosis, presumably because both components are malignant.² Typically, the neuroendocrine portion of the neoplasm is grade 3 with >20 mitoses per 10 high-powered fields (HPF) and/or a Ki-67 proliferative index of >20%.  The only hope of cure is offered by gastrectomy. In patients who have advanced disease platinum-based chemotherapy, such as a combination of cisplatin and etoposide, has been recommended.