Introduction: Pseudomyxoma peritonei (PMP) is a rare clinical entity (1 case per million inhabitants), characterized by the accumulation of mucinous material within the abdominal cavity due to the rupture of a mucin-producing neoplasm, most commonly of appendiceal origin. The treatment of this condition is surgical, based on complete cytoreduction of all visible mucinous lesions (including the primary tumor, implants, as well as affected peritoneum and/or organs), combined with hyperthermic intraperitoneal chemotherapy (HIPEC). The extent of cytoreduction is the most significant prognostic factor, with overall survival reaching up to 80% at 5 years in some series. Therefore, careful surgical planning and management in specialized centers are essential.

Case report: We present the case of a 48-year-old female patient with no relevant medical history, who underwent surgery for acute appendicitis at another institution. Histopathological analysis revealed a mucinous adenocarcinoma of the appendix, staged as T4aG2, with lymphatic invasion but negative surgical margins. Colonoscopy, liver MRI, and PET-CT showed no pathological findings, and a laparoscopic right hemicolectomy with HIPEC was planned based on intraoperative findings. Surgical procedure: the patient was positioned in the Lloyd-Davis lithotomy position, and five laparoscopic ports were placed. An initial exploratory laparoscopy was performed to determine the Peritoneal Cancer Index (PCI). Implants were identified in the lower left quadrant (1), lower right quadrant (3), cecal serosa (1), and greater omentum (1). A right hemicolectomy with D3 lymphadenectomy was performed, along with bilateral parietopelvic peritonectomy and bilateral adnexectomy. An omentectomy was also carried out. An extracorporeal double-layer ileocolic anastomosis was constructed manually, following the standardized technique of the unit, via an extended umbilical trocar site. Subsequently, HIPEC was administered using mitomycin C at a dose of 30 mg/m² at 42^o C for 60 minutes. The patient was discharged on postoperative day seven without complications. She is currently receiving adjuvant chemotherapy following the XELOX regimen.

Discussion: Exploratory laparoscopy to assess the PCI must be thorough and meticulous; thus, it is essential to train oncologic surgeons in performing this procedure. Moreover, in patients with pseudomyxoma peritonei and low disease burden, cytoreduction and HIPEC via a laparoscopic approach is both feasible and safe.