Mucinous epithelial neoplasm, which can be benign (mucinous cystadenoma), borderline (low malignant potential), or malignant (mucinous cystadenocarcinoma)

Multilocular cystic mass with low-level echoes

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  Mucin creates low-level echoes within loculi

  
  
  
  
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    Echogenicity can be variable depending on concentration of mucin

  
  
  
  
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  Papillary projections much less common than in serous tumors

  
  
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  Solid components increase suspicion for malignancy

Variable in size but often large; may fill entire pelvis and extend into upper abdomen

Pseudomyxoma peritonei is potential form of peritoneal spread

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  More echogenic than simple ascites

  
  
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  Amorphous, mucoid material insinuating itself around mesentery, bowel, and solid organs

  
  
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  Has mass effect with scalloping along solid organs (especially liver) and bowel matted posteriorly (rather than free-floating)

Endometrioma

Serous cystadenoma/carcinoma

Method of spread

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  Intraperitoneal dissemination most common (pseudomyxoma peritonei)

  
  
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  Direct extension to surrounding organs

  
  
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  Lymphatic spread to paraaortic and pelvic nodes

Massive tumors can cause weight gain and distended abdomen

CA-125 not useful for mucinous tumors: False-negative in 30%

Mucinous tumors 2nd most common epithelial neoplasm

Gelatinous, insinuating nature of pseudomyxoma peritonei makes complete resection difficult

Mucinous tumors are less commonly malignant than serous tumors