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case_images: The tumor was 6 mm x 8 mm in the lower rectum about 5 cm from the anal verge.
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case_images: During a routine physical examination, a small rectal tumor measuring approximately 6 mm x 8 mm (Fig. 1) was accidentally discovered by colonoscopy in a 47-year-old man who was previously in good health, who had no any other diseases and no operation history before.
case_images: Histopathological and Immunohistochemical staining of the resected specimen (primary tumor) indicated that the tumor was neuroendocrine tumor, tumor tissue invaded the muscularis mucosae and fibrovascular tissue of submucosa, the Ki-67 index was 6 %. (Fig. A: Histopathological staining; Fig. B: Immunohistochemical staining).
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case_images: The pathological diagnosis revealed a NET G2, with a Ki-67 index of 6 % (Fig. 2) and a nuclear division count of 2/10HPF (high power field).
case_images: CT(Fig. A) and MRI(Fig. B) indicated many enlarged lymph nodes in the mesorectum and on the both sides of the lateral pelvic space(red circle). PET-CT(Fig. C) showed that the lymph nodes in the mesorectum was positive. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
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case_images: However, approximately one month later, abdominal contrast-enhanced CT and T2-weighted MRI revealed enlarged lymph nodes (Fig. 3), raising suspicion of mesorectal lymph nodes and lateral lymph nodes metastasis on the left side.
case_images: TME and lateral lymph node dissection were performed under laparoscopy. The figure showed that both sides of the lateral lymph nodes were removed. (A: the common iliac artery; B: the common iliac vein. C: the left obturator nerve; D: the right obturator nerve).
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case_images: Prior to the second operation, we conducted a case discussion and consider that the patient had NET with lymph nodes in the mesorectum and lateral lymph nodes metastasis and recommended treating with TME and bilateral lymph node dissection (Fig. 4).