A 67-year-old woman with Sjogren syndrome presented with hematochezia. Colonoscopy showed a 2-cm–diameter pedunculated lesion with a slightly depressed crest in the sigmoid colon (Figure A). Hematoxylin-eosin staining of the endoscopic mucosal resection specimen showed moderately differentiated adenocarcinoma with stalk invasion (Figure B). Elastica-van Gieson staining showed vascular invasion. Laparoscopic sigmoidectomy with lymphadenectomy was performed. The surgical specimen demonstrated a single metastatic lymph node (LN) and extramural tumor deposits (ETDs) in the mesocolon (Figure C and Figure D). We diagnosed pT1N1M0, stage IIIA, with adjuvant fluorouracil and without recurrence 5 years after surgery.
ETDs in colorectal carcinoma (CRC) are associated with tumor progression and poor prognoses and observed in 16.9%–18.2%. The eighth edition of the American Joint Committee on Cancer Tumor-Node-Metastasis staging considers discrete tumor foci in the pericolorectal fat with specific sizes following the contour rule without residual LN as peritumoral tumor deposits. ETDs are observed in pT2-4 CRCs, except the pathologically diagnosed cases of mucosal or submucosal invasion (pT1). This is the first practical description of ETDs in pT1 CRC. Historically, ETDs have been surmised as discontinuous tumor spread, venous invasion with extravascular spread, or replaced LN. The ETDs in pT1 CRC may imply they would rather be replaced LN essentially.
Footnotes
Conflicts of Interest: The authors disclose no conflicts.
Funding: The authors report no funding.
Ethical Statement: The corresponding author, on behalf of all authors, jointly and severally, certifies that their institution has approved the protocol for any investigation involving humans or animals and that all experimentation was conducted in conformity with ethical and humane principles of research.
Reporting Guidelines: Helsinki Declaration.