Intramucosal colorectal carcinoma with lymphovascular invasion: clinicopathological characteristics of nine cases

Aims Recent studies have provided the concept of invasive intramucosal colorectal carcinoma ( CRC ), and a case of intramucosal CRC with lymphatic invasion has been reported; however, the characteristics of such cases and the risk of lymph node metastasis have never been investigated. Therefore, we aimed to assess the pathological characteristics of intramucosal CRC s with lymphovascular invasion as well as the possibility of lymph node metastasis as an indication for additional surgery. Methods and results To delineate the histological features of intramucosal CRC s with lymphovascular invasion, we analysed several histological features and compared their incidence among nine such cases, as well as 20 other cases of intramucosal CRC s without lymphovascular invasion. High‐grade tumour budding and a pattern of ‘eosinophilic cytoplasm and round nuclei with inflammatory reaction ( ERI )’ were morphological characteristics of intramucosal CRC s with lymphovascular invasion, compared with those without lymphovascular invasion (both P < 0.05). Among the seven lymph node‐dissected cases of intramucosal CRC s with lymphovascular invasion, none showed lymph node metastasis. Conclusions In intramucosal CRC s with lymphovascular invasion, high‐grade tumour budding and the ‘ ERI ’ pattern are morphological characteristics that are distinct from those of non‐invasive CRC , which is synonymous with high‐grade dysplasia. Further studies using a larger number of cases by focusing on the above‐mentioned histological pattern are expected to clarify the potential of lymph node metastasis of such cases.