*2.1.6.1. Adenocarcinoma with lymphoid stroma (lymphoepithelioma-like or medullary carcinoma)*

Typically, poorly cohesive or vague tubular-forming tumour cells are associated with prominent lymphoid stroma. Often small lymphocytes are scattered between tumour cells. Poorly cohesive tumour cells can be misinterpreted as lymphatic blasts. Typically, this subtype is EBV-related and it is easy to detect EBV-RNA using *in-situ*-test like EBER. Furthermore, carcinoma cells are often immunohistochemically strong PD-L1 positive. Nevertheless, not all EBV-related adenocarcinomas show the typical medullary morphological features. Some carcinomas of this subtype are microsatellite-instable easy and cost-effective detectable using immunohistochemistry for MLH1 (MSH2, MLH6 and PMS2). The loss of one (or more) of these DNA-repair proteins in tumour cell nuclei is in keeping with microsatellite-instability.

#### *2.1.6.2. Squamous cell carcinoma*

A pure gastric squamous cell carcinoma is very rare and is suspicious for a metastasis. Sometimes a mixed adeno-squamous cell carcinoma can be seen.
