Pseudomyxoma peritonei originating from transverse colon mucinous adenocarcinoma: CT and MRI insights from a rare case.

Pseudomyxoma peritonei (PMP) is a rare clinical condition, most commonly arising from appendiceal or ovarian mucinous neoplasms. This case report describes an exceptionally rare origin of PMP from a mucinous adenocarcinoma of the transverse colon, highlighting unique diagnostic and therapeutic challenges. Multimodality imaging played a crucial role in the diagnostic process, with computed tomography (CT) providing initial identification of low-attenuation peritoneal lesions with characteristic scalloping of visceral surfaces. Magnetic resonance imaging (MRI), less frequently reported in the literature for PMP, offered superior lesion characterization through high-resolution T2-weighted sequences, revealing hyperintense mucinous deposits. The combination of CT and MRI findings facilitated accurate diagnosis and staging, guiding surgical planning. Management involved cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC), which remains the standard approach for PMP, improving survival in selected patients. This case underscores the critical role of comprehensive radiological assessment, particularly the added value of MRI, in enhancing diagnostic accuracy and optimizing patient outcomes in rare presentations of PMP.