Ovarian serous cystadenocarcinoma, the most common malignant epithelial ovarian tumour, may show psammoma bodies and presents with complex cystic and solid components with enhancing septations and nodules on imaging.
Description
Ovarian serous cystadenocarcinoma is a malignant neoplasm of the ovary, originating from the ovarian surface epithelium. It is the most common malignant epithelial ovarian tumour, characterised by complex cystic and solid growth pattern.
Pathogenesis
The exact pathogenesis is not fully understood, but it is thought to arise from the ovarian surface epithelium or from invaginated epithelium forming cortical inclusion cysts. Some theories also suggest it might arise from fallopian tube epithelium that implants on the ovarian surface.
Subtypes
- Low-grade serous cystadenocarcinoma (Type 1, LGSC): Characterised by indolent growth and relative chemoresistance. Less common than HGSC (10% of cases). Stable genome and without TP53 mutations
- High-grade serous cystadenocarcinoma (Type II, HGSC): More aggressive and chemosensitive, more common of the two subtypes (90% of cases). Associated with BRCA1 and BRCA2. Genetically highly unstable; majority have TP53 mutations.
Epidemiology, Risk Factors & Associations
- Most common in postmenopausal women.
- Associated risk factors include nulliparity, early menarche, late menopause, and family history of ovarian or breast cancer (BRCA1 and BRCA2 mutations).
- Associated with TP53 mutations.
Clinical Features
- Often asymptomatic in early stages.
- Advanced disease can present with abdominal distension, pain, or ascites.
- May be associated with the Meigs syndrome (ascites and pleural effusion).
Complications
- Common sites of metastasis include the peritoneum, lymph nodes, and liver.
Pathological Features
Histopathology
- Macroscopic: Large, unilateral, multilocular cystic tumour with solid areas.
- Microscopic: Epithelium of tumour resembles the lining of fallopian tube. Stromal invasion, complex architecture, confluent cellular growth and nuclear atypia. One of the hallmarks of serous cystadenocarcinoma (especially low-grade serous carcinoma) is the formation of psammoma bodies (microscopic calcifications).
Serology
- Ca-125 increased (>35 U/mL) in majority of cases (80%), greater in advanced staged disease.
Radiological Features
General Features
- Characteristically demonstrates a large complex cystic mass with solid/papillary components arising from ovary
- Peripheral or irregular calcifications may be seen (20-30% of cases).
- Bilateral in majority of cases
- Low-grade serous carcinoma (LGSC) tend to be cystic masses with septations and papillary solid components
- High-grade serous carcinoma (HGSC) tend to be complex cystic mass with large solid components
- May also appear entirely solid
- Associated findings include ascites, lymphadenopathy, peritoneal disease.
CT
- Non-contrast: Complex cystic and solid mass, may show calcifications.
- Contrast-enhanced: Enhancing septations and solid components.
MRI
- T1WI: Low to intermediate signal intensity cystic mass with intermediate solid components
- T2WI: High signal intensity in cystic parts, low signal intensity in solid components.
- T1 C+ (post-contrast): Enhancing septations and solid components.
US
- B-mode: Large, complex, multilocular cystic mass with solid components and possible calcifications. Thick walls, septations, nodules, or papillary projections.
- Colour Doppler: May show vascularity within the solid components or septations.
NM
- PET FDG: Can demonstrate increased uptake in the solid components or any metastatic sites.
Grading and Staging
The FIGO (International Federation of Gynecology and Obstetrics) system is used for staging ovarian carcinomas.
Diagnosis
Diagnosis is typically made based on clinical findings, imaging, and confirmed with histopathological examination of surgical specimens.
Differential Diagnosis
- Benign cystadenoma (serous or mucinous): Usually smaller (<4 cm), with thinner walls (<3 mm) and no solid components. No ascites, peritoneal disease or lymphadenopathy.
- Mucinous cystadenocarcinoma: Typically larger and multiloculated with multiple thin septations. The presence of a mucin-debris level may be seen. These tumours often have higher attenuation on CT and do not enhance as much as serous cystadenocarcinoma. More likely to be unilateral compared to serous cystadenocarcinoma.
- Endometrioma: These are T1 hyperintense lesions due to haemorrhagic content, unlike the mixed signal intensity of serous cystadenocarcinoma. They are typically smaller, bilateral, and associated with endometriosis, helping to differentiate from serous cystadenocarcinoma.
- Metastases to the ovary (Krukenberg tumour): Often bilateral and typically solid or with complex cystic-solid appearance. The presence of signet ring cells on histopathology is a distinguishing feature. History of a known primary malignancy can be helpful.
- Brenner tumour: These are usually small, solid, and can demonstrate calcification. They are mostly benign and tend to have a more homogeneous appearance than the complex cystic-solid architecture of serous cystadenocarcinoma.
- Mature cystic teratoma: Also known as dermoid cyst have a characteristic appearance of fat, calcification, and teeth, which are not typically seen in serous cystadenocarcinoma. May demonstrate a non-enhancing dermoid plug, a.k.a. Rokitansky nodule.
Management
The initial management involves surgical debulking and staging, followed by platinum-based chemotherapy. The role of the radiologist is crucial in preoperative assessment, determining the extent of disease, and guiding biopsy if needed.