One of the epithelial-stromal tumors containing mucoid material

Most mucinous cystadenomas are benign tumors, although 20% can be borderline (low malignant potential) or malignant. Benign mucinous cystadenomas represent 20% to 25% of all benign ovarian tumors and occur mostly during the third to fifth decades. These mucinous tumors are comprised most often of the mucin-producing cell type similar to a cell type that lines the intestinal tract, although a minority of the tumors have endocervical-like mucin-producing cells. Some tumors may contain both cell types.

Mucinous cystadenomas are multilocular in 50% of cases, with solid components or papillary projections in 40% of borderline and malignant cases. The fluid inside the cystic area typically contains low-level echoes much like an endometrioma; however, when interrogated with Doppler, the echoes stream compared with those in endometriomas, which usually do not. The different compartments of the cystic mass may differ as to the texture of the echoes within, likely secondary to different cell types within a single tumor. When internal nodules with blood flow are present, the possibility of a borderline or invasive malignancy must be considered. Typically, borderline malignancies have fewer nodules and less blood flow within them compared with invasive tumors, although this is a very subjective finding.