Abstract
BACKGROUND: Pseudomyxoma peritonei (PMP) is a rare neoplastic disease that can occasionally present with pulmonary metastases as an even rarer manifestation. Although cytoreductive surgery represents the primary treatment option for PMP, surgical management of pulmonary metastases presents unique challenges owing to their mucinous nature. The aim of this case series was to present key considerations for the surgical management of PMP lung metastases, particularly regarding solid-appearing nodules that are impalpable during surgical resection, requiring more extensive resection owing to the risk of recurrence. CASE PRESENTATION: Between November 2013 and May 2023, we performed a total of 13 surgical procedures for pulmonary metastases in seven patients with PMP at our institution. During these procedures, 18 pulmonary lesions were resected. Some patients underwent multiple surgeries; multiple lesions were resected in a single procedure in certain cases. Notable characteristics of PMP pulmonary metastases, attributed to their mucinous dissemination pattern, included cases wherein subpleural solid nodules that would typically be palpable in patients with conventional solid tumour metastases were non-palpable and cases requiring right upper lobectomy following repeated surgical margin recurrence. Median follow-up results showed a progression-free survival of 20.0 months and overall survival of 40.3 months. Three of the seven patients experienced postoperative recurrence, with two patients having intrapulmonary metastatic recurrence involving low-grade tumours. CONCLUSIONS: Surgical resection can be an effective treatment option for PMP pulmonary metastases; however, careful patient selection and appropriate surgical planning are essential. The unique characteristics of PMP metastases necessitate specific surgical strategies. Since computed tomography-apparent solid nodules may be non-palpable intraoperatively and surgical margin recurrence should be avoided, selecting surgical approaches that minimise unnecessary lung palpation, such as preoperative marking or anatomical lung resection, is crucial. The mechanisms of PMP pulmonary metastasis development and progression remain unclear, warranting further research into blood-borne dissemination patterns and optimal surgical techniques for non-palpable lesions.