Intra‐pancreatic, Extra‐tumoral Perineural Invasion ( nex )

A histopathologic study of 65 resected malignant lesions of the pancreas was done to search for a histologic predictor for the presence of extra‐pancreatic neural plexus involvement by carcinoma cells. Extra‐pancreatic neural plexus invasion by pancreas carcinoma cells, p/x(+), was detected in 28 of 65 cases (43%). plx ( + ) was not significantly associated with tumor location, tumor size, histologic type, or lymph vessel invasion (ly) by carcinoma cells but was significantly associated with rpe. P/x(+) was also significantly associated with mixed moderate and severe degrees of intra‐pancreatic neural invasion (ne 2 /ne 3 group), but not with mixed no and slight degrees (ne 0 /ne, group). However, fourteen p/x(+) cases were excluded in the ne 2 / ne 3 group; they were found in the ne, group. Therefore, ne factors appear to have a certain but limited usefulness for the prediction of plx ( + ). When a perineural invasion by tumor cells was found within the pancreas but outside of the major mass of cancer, it was designated “intra‐pancreatic, extra‐tumoral perineural invasion (nex)”. The presence of nex(+) was found in 37 cases, in which 24 out of the 28 p/x (+) cases (85.7%) were included. A statistically significant association was found between p/x (+) and nex(+). In particular, 12 out of the 14 p/x ‐ positive ne, cases were nex (+). In ne, cases, 33.3% (14/42) were p/x (+), whereas in ne 1 and nex (+) cases, 60% (12/20) were p/x (+). There was a statistical significance between these two figures (p < 0.05). Thus, nex(+) appears to be a useful indicator for p/x (+), particularly in ne , cases.