How are ovarian tumors of low malignant potential (LMP) diagnosed?

Updated: Aug 10, 2020
  • Author: Andrew E Green, MD; Chief Editor: Yukio Sonoda, MD  more...
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Answer

All histologic subtypes of endothelial ovarian cancer have serous, mucinous, endometrioid, clear cell, and Brenner low malignant potential (LMP) variants, with the essential feature being that no invasion occurs. Mucinous and serous types are most common (see the image below). Invasion is difficult to interpret in mucinous tumors, and the requisite microscopic feature is epithelial stratification exceeding 3 cell layers with associated nuclear atypia. Ovarian tumors require very careful pathologic examination, with sufficient numbers of sections taken to ensure adequate assessment. Particular care must be taken with frozen section interpretation of large mucinous tumors at the time of surgery.

Inside of a large, smooth-surfaced tumor replacing Inside of a large, smooth-surfaced tumor replacing the ovary. Final histologic studies indicated the tumor was a mucinous carcinoma of low malignant potential. Note the multiple cysts with thick septa between. This tumor was extensively sectioned and was a mucinous carcinoma of low malignant potential.

Serous LMP tumors usually are unilocular, more often bilateral than mucinous LMP tumors, and filled with clear serous fluid. The external surface normally is smooth, but excrescences on the outside surface and papillary projections on the inside may be observed. Mucinous LMP tumors are multicystic with a smooth outer surface. Both types may be large.

LMP tumors can metastasize throughout the abdominal cavity and elsewhere. Metastases can be differentiated microscopically as those without invasion and those with invasion.


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