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Findings: A single axial section from a CT scan of the abdomen, performed with oral contrast demonstrates thickening of the greater omentum. The structure may be found to lie just anterior to the transverse colon and casts a characteristic heterogeneous attenuation pattern.
Diagnosis: Omental caking.
Discussion: The peritoneum, mesentery, and greater omentum are frequent sites of metastatic seeding from primary malignancies. Ovarian carcinoma is the primary neoplasm that most often metastasizes to the omentum, followed in frequency, to a lesser degree, by carcinomas of the stomach, colon, pancreas, and others.
The classic finding of "omental caking" arises secondary to tumor-cell implantation on the omental surface, followed by serosal invasion and proliferation in the omental fat. Eventually, the omental fat becomes entirely replaced by tumor, resulting in a thick, confluent, soft-tissue mass.
The greater omentum has been dubbed "the policeman of the abdomen", because of its tendency to move toward and surround inflammatory processes in the abdomen, thus preventing their diffuse spread. It is amusingly coincidental that the handy mnemonic issued to help remember those primary malignancies which are metastatic to the greater omentum is "C.O.P.S."! That is:
Colon Ovary Pancreas StomachReferences:
Cooper C, Jeffrey RB, Silverman PM, Federle MP, and Chun GH. Computed Tomography
of Omental Pathology. J Comput Assist Tomog. 1886; 10(1):62-66.
Haaga JR. The Peritoneum and Mesentery. In: Computed Tomography and Magnetic
Resonance Imaging of the Whole Body, 3rd edition. Haaga JR, Lanzieri CF, Sartoris DJ
and Zerhouni EA, eds. Mosby-Year Book, Inc., 1994.
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