Diagnostic Ultrasound - Abdomen and Pelvis

Mucinous Ovarian Cystadenoma/Carcinoma
TERMINOLOGY
Abbreviations
• Benign or malignant mucinous tumor
Definitions
• Mucinous epithelial neoplasm, which can be benign
(mucinous cystadenoma), borderline (low malignant
potential), or malignant (mucinous cystadenocarcinoma)
IMAGING
General Features
• Best diagnostic clue
○ Multilocular cystic mass with low-level internal echoes
• Location
○ Bilateral in 5% of benign and 20% of malignant tumors
• Size
○ Variable in size, but often large, filling entire pelvis and
extending into upper abdomen
○ Some of the largest tumors ever reported are mucinous
cystadenomas
– Massive size alone can suggest mucinous etiology
Ultrasonographic Findings
• Grayscale ultrasound
○ Typically multiloculated with thin septations
○ Papillary projections much less common than in serous
tumors
○ Mucin creates low-level echoes within loculi
– Typically have multiple loculi of varying echogenicity
– Echogenicity variable depending on concentration of
mucin
○ Solid components increase suspicion for malignancy
○ Pseudomyxoma peritonei: Potential form of peritoneal
spread with amorphous, mucoid material insinuating
itself around mesentery, bowel, and solid organs
– More echogenic than simple ascites
– Has mass effect with scalloping along solid organs
(especially liver) and bowel matted posteriorly (rather
than free floating)
– May have subtle septations
• Color Doppler
○ Vascularity seen within solid components
CT Findings
• Variable attenuation of loculi, depending on concentration
of mucin
• Peritoneal metastases often low attenuation
○ May be difficult to differentiate from fluid-filled bowel
• Enhancement of solid portions with contrast
MR Findings
• Signal intensity varies depending on concentration of mucin
• Loculi with high concentration of mucin will be higher signal
on T1WI and lower signal on T2WI
○ Creates a stained glass appearance
DIFFERENTIAL DIAGNOSIS
Endometriomas
• Also contain low-level echoes
• MRI helpful: Blood high signal on T1WI with T2 shading
Serous Cystadenoma/Carcinoma
• More often unilocular
• Cyst contents not as echogenic
• Papillary projections common
Germ Cell Tumors
• Can have low-level echoes similar to mucin
• Typically more complicated with calcifications, fluid-fluid
levels, etc.
Hemorrhagic Cyst
• Smaller and unilocular
• Resolves on follow-up scan
Mucocele
• Dilated appendix filled with mucinous material
PATHOLOGY
General Features
• Etiology
○ Not completely understood
○ 1 theory is "incessant ovulation": Repeated microtrauma
with cellular repair to surface epithelium
– Increased risk: Nulliparity, early menarche, late
menopause (more ovulatory cycles)
– Reduced risk: Multiparity, late menarche, early
menopause, oral contraceptive use (fewer ovulatory
cycles)
• Genetics
○ Hereditary causes in 5-10% of ovarian cancers (mutations
in BRCA1 and BRCA2 tumor suppressor genes)
• Associated abnormalities
○ May occasionally be hormonally active, producing
estrogen
• Ovarian neoplasms
○ Epithelial tumors: 60-70% of all tumors; 85-90% of
malignancies
○ Germ cell tumors: 15-20% of all tumors; 3-5% of
malignancies
○ Sex cord-stromal tumors: 5-10% of all tumors; 2-3% of
malignancies
○ Metastases and lymphoma: 5-10% of all tumors; 5-10%
of malignancies
• Benign epithelial tumors
○ Serous cystadenoma: 20-25%
○ Mucinous cystadenoma: 20-25%
• Malignant epithelial tumors
○ Serous cystadenocarcinoma: 40-50%
○ Endometrioid carcinoma: 20-25%
○ Mucinous cystadenocarcinoma: 5-10%
○ Clear cell carcinoma: 5-10%
○ Brenner tumor: 1-2%
○ Undifferentiated carcinoma: 4-5%
• Method of spread
○ Intraperitoneal dissemination most common
– Greater omentum, right subphrenic region, and pouch
of Douglas most common sites found at surgery
○ Direct extension to surrounding organs
○ Lymphatic spread to paraaortic and pelvic nodes
○ Hematogenous spread least common
Diagnoses: Female Pelvis
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