A Case Report of a Grade G2 Rectal Neuroendocrine Neoplasm with Perineural Invasion and Lymph Node Metastasis

Rectal neuroendocrine tumors (R-NETs) are a common type of gastrointestinal neuroendocrine tumor, with an incidence that has increased due to advancements in endoscopic technology. Most are small, low-grade, and have a favorable prognosis, but their clinical presentation is nonspecific and easily confused with benign lesions, posing challenges in differential diagnosis, especially for medium-sized lesions.

This article reports a case of a 50-year-old male patient who presented with nonspecific lower abdominal pain. Postoperative pathology confirmed a G2-grade, pT2N1 stage R-NET with perineural invasion, lymph node metastasis, and tumor nodule formation. The uniqueness of this case lies in its aggressive biological behavior. Preoperative biopsy indicated G2 grade, while postoperative pathology revealed more extensive infiltration and metastasis. Additionally, the tumor coexisted with tubular adenoma, increasing diagnostic complexity. The patient underwent laparoscopic radical surgery combined with postoperative systemic therapy using octreotide and surufatinib.

The significance of this case highlights the need for clinical vigilance regarding the potential aggressiveness of G2-grade R-NETs, emphasizing the critical role of multidisciplinary collaboration, comprehensive pathological evaluation, and individualized stage-based treatment in optimizing diagnosis and prognosis.