Table 1 .
Paris staging system for primary gastrointestinal lymphomas*†
| TX | Lymphoma extent not specified |
| TO | No evidence of lymphoma |
| T1 | Lymphoma confined to the mucosa/submucosa |
| T1m | Lymphoma confined to mucosa |
| T1sm | Lymphoma confined to submucosa |
| T2 | Lymphoma infiltrates muscularis propria or subserosa |
| T3 | Lymphoma penetrates serosa (visceral peritoneum) without invasion of adjacent structures |
| T4 | Lymphoma invades adjacent structures or organs |
| NX | Involvement of lymph nodes not assessed |
| NO | No evidence of lymph node involvement |
| N1‡ | Involvement of regional lymph nodes |
| N2 | Involvement of intra-abdominal lymph nodes beyond the regional area |
| N3 | Spread to extra-abdominal lymph nodes |
| MX | Dissemination of lymphoma not assessed |
| MO | No evidence of extranodal dissemination |
| M1 | Non-continuous involvement of separate site in gastrointestinal tract (eg, stomach and rectum) |
| M2 | Non-continuous involvement of other tissues (eg, peritoneum, pleura) or organs (eg, tonsils, parotid gland, ocular adnexa, lung, liver, spleen, kidney, breast etc.) |
| BX | Involvement of bone marrow not assessed |
| B0 | No evidence of bone marrow involvement |
| B1 | Lymphomatous infiltration of bone marrow |
| TNM | Clinical staging: status of tumour, node, metastasis, bone marrow |
| pTNMB | Histopathological staging: status of tumor, node, metastasis, bone marrow |
| pN | The histological examination will ordinarily include 6 or more lymph nodes |
*Valid for lymphomas originating from the gastro-oesophageal junction to the anus (as defined by identical histomorphological structure).
†In case of more than one visible lesion synchronously originating in the gastrointestinal tract, give the characteristics of the more advanced lesion.
‡Anatomical designation of lymph nodes as “regional” according to site: (a) stomach: perigastric nodes and those located along the ramifications of the coeliac artery (that is, left gastric artery, common hepatic artery, splenic artery) in accordance with compartments I and II of the Japanese Research Society for Gastric Cancer (1995); (b) duodenum: pancreaticoduodenal, pyloric, hepatic, and superior mesenteric nodes; (c) jejunum/ileum: mesenteric nodes and, for the terminal ileum only, the ileocolic as well as the posterior caecal nodes; (d) colorectum: pericolic and perirectal nodes and those located along the ileocolic, right, middle, and left colic, inferior mesenteric, superior rectal, and internal iliac arteries.