PMC9800599_01
Preoperative endoscopic and imaging examination results. (A) Colonoscopy revealed the tumor was 2.4 cm x 2.0 cm in diameter in the lower rectum with a wide stratum. (B) CT revealed no LLNs enlargement in the mesorectum and on both sides of the lateral pelvic space. (C) The EUS reveals the lesion invades the submucosal layer and no LLNM. (D)
99Tcm-octreotide SPECT revealed high uptake in the rectal cavity and no uptake in either side of the lateral pelvic space.
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Colonoscopy revealed the mass is 2.4 cm x 2.0 cm in size, with a wide stratum, poor mobility, and a rough but intact surface mucosa ( Figure 1A ). A CT examination revealed the tumor is significantly enhanced and the fat gap around the tumor is blurred ( Figure 1B ). The endoscopic ultrasound (EUS) reveals the lesion invades the submucosal layer, and some levels are suspected of invading the innate muscular layer ( Figure 1C ). But, neither CT nor EUS reveals pelvic, abdominal, or retroperitoneal enlarged LNs. 99Tcm-octreotide SPECT images revealed high uptake in the rectal cavity which is consistent with neuroendocrine tumor manifestations ( Figure 1D ).
4K fluorescence laparoscopic surgical procedure. (A) Expose the region of the left iliac vessel. (B) Expose the region of the right iliac vessel. (C) Positive ICG-fluorescent staining of the left LLNs. (D) Negative fluorescent staining of the right LLNs. (E) Dissect the left LLNs. (F) Specimen of the left LLNs.
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After opening the peritoneum, the internal iliac vessels were subsequently cleared from the lymphatic tissue at a safe distance from the lateral side of the pelvic plexus ( Figures 2A, B ). In the obturator space, fluorescence staining of the left LLNs is visible ( Figure 2C ). In contrast, LLNs on the right side are not visible with fluorescence staining ( Figure 2D ). Figures 2E, F ). Following completion of the left LLND, only external vessels, internal iliac vessels and their branches, the obturator nerves, and the pelvic plexus remained.
Histopathological findings of the resected specimen (primary tumor and left LLNs). (A) Macroscopic findings of the resected specimen. (B, C) HE staining showed that the primary tumor cells spread in the organ-like features, trabecular, glandular, and gyri-like (B magnification, x20, C magnification, x400). (D, E) HE staining showed that left LLNs have similar findings to those of the primary tumor (D magnification, x20, E magnification, x100).
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The resected specimen indicated that the primary tumor was 20mm in diameter and invaded peri-intestinal adipose tissue ( Figure 3A ). Hematoxylin and eosin (HE) staining of the primary tumor and LLNs showed that the tumor cells spread in the organ-like features, trabecular, glandular, gyri-like ( Figures 3B-E ).
Immunohistochemical staining (magnification, x100) of the resected specimen (primary tumor and left LLNs). (A) The Ki-67 index was 1-2%. (B) The CD56 was 3+. (C) The synaptophysin was 3+. (D) The CgA was 3+. (E) The SSTR2 was 2+. (F) The Rb-1 was 2+.
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A pathological diagnosis of NET G1(pT3N1) was confirmed according to a Ki-67 index of 1-2% ( Figure 4A ).