Great peritoneal pretenders: imaging mimickers of peritoneal carcinomatosis

Peritoneal pathology is commonly encountered in clinical practice yet remains diagnostically challenging due to substantial overlap in imaging appearances. Findings such as ascites, peritoneal thickening, and nodularity are often attributed to peritoneal carcinomatosis (PC), a metastatic condition associated with a worse prognosis than metastatic disease without peritoneal involvement. Accurate diagnosis is therefore essential for staging, treatment planning, and prognostication. However, a variety of benign and malignant conditions can produce similar findings. These "peritoneal pretenders" include inflammatory, infectious, traumatic, iatrogenic, and non-carcinomatous malignant processes. This imaging similarity can lead to diagnostic uncertainty, unnecessary investigations, or delays in appropriate management. Understanding peritoneal anatomy, fluid dynamics, and predictable patterns of disease spread is critical for accurate localization and interpretation. This review presents a practical pattern-based multimodality imaging approach to peritoneal pathology, integrating clinical context, disease acuity, imaging morphology and distribution, and targeted advanced imaging to distinguish PC from its benign and malignant mimics.