Definition of Carcinomatosis
Carcinomatosis is the widespread dissemination of cancer cells throughout a serous membrane-lined body cavity, most commonly referring to peritoneal carcinomatosis (spread throughout the peritoneal cavity) or leptomeningeal carcinomatosis (spread throughout the leptomeninges and subarachnoid space). 1, 2
Anatomic Variants
Peritoneal carcinomatosis represents the dissemination of malignant cells throughout the lining of the abdominal cavity, appearing as the second most common presentation of distant metastasis in colon cancer 3
Leptomeningeal carcinomatosis (also termed neoplastic meningitis) defines the spread of tumor cells within the leptomeninges and subarachnoid space, and can be further specified by primary tumor type as leptomeningeal carcinomatosis, gliomatosis, or lymphomatosis 1
The term can be modified by the primary tumor origin—for example, "leptomeningeal carcinomatosis" specifically indicates spread from epithelial carcinomas 1
Pathophysiology
Carcinomatosis develops when cancer cells breach the basement membrane of their tissue of origin and gain access to body cavities, where they implant and proliferate along serous surfaces 4
In peritoneal carcinomatosis, the pattern and extent of dissemination varies based on the primary tumor site, histologic grade, and biologic aggressiveness of the malignancy 2
The condition represents an advanced stage of disease that historically carried terminal prognosis, though modern treatment approaches have challenged this paradigm in selected patients 5, 2
Clinical Significance
Peritoneal carcinomatosis commonly occurs with digestive tract cancers (particularly gastric and colorectal), ovarian cancer, and appendiceal malignancies 1, 3
Leptomeningeal carcinomatosis occurs in approximately 10% of patients with metastatic solid tumors, most frequently from breast cancer, lung cancer, and melanoma 1
The presence of carcinomatosis indicates widespread disease but does not automatically preclude curative-intent treatment in carefully selected patients with limited disease burden 1, 5
Diagnostic Features
Peritoneal carcinomatosis presents with tumor nodules studding the peritoneal surfaces, often accompanied by malignant ascites that causes significant patient discomfort 2
Leptomeningeal carcinomatosis is definitively diagnosed by identification of malignant cells on cerebrospinal fluid cytology, with imaging abnormalities visible in 70-80% of cases on gadolinium-enhanced T1-weighted MRI 1
The extent of peritoneal disease can be quantified using the Peritoneal Cancer Index (PCI), with scores <20 generally indicating more favorable prognosis for cytoreductive approaches 1