Ovarian Malignancy is the Most Likely Primary Site
The combination of pleural effusion, ascites, and an adnexal mass in an elderly female is most consistent with ovarian malignancy (Answer A). This clinical triad represents classic features of advanced ovarian cancer with peritoneal and pleural dissemination.
Clinical Reasoning Based on Imaging Features
The ACR Appropriateness Criteria specifically identify ascites and pleural effusions as important imaging features in the evaluation of malignant adnexal masses 1. According to the IOTA Simple Rules for predicting malignancy in adnexal masses, ascites is one of the five key malignant features (M features) that strongly suggest ovarian cancer 1.
Why Ovarian Cancer is Most Likely:
- Ovarian cancer is the most common gynecologic malignancy to present with this triad of findings 2
- Pleural effusion occurs in ovarian cancer through peritoneal-pleural communication and lymphatic obstruction, with the right hemithorax being most commonly affected 1, 2
- High-grade serous ovarian carcinoma frequently presents with both ascites and pleural effusion as initial manifestations 2
- The adnexal mass location (right ovary/fallopian tube) directly correlates with the primary tumor site in ovarian malignancy 1
Differential Considerations
Meigs Syndrome (Benign Mimicker):
While Meigs syndrome presents with an identical triad of ovarian mass, ascites, and pleural effusion, it is caused by benign ovarian tumors (fibromas, fibrothecomas, thecomas) and is considerably rarer than malignant disease 3, 4, 5, 6. However, in an elderly postmenopausal woman, malignancy must be presumed until proven otherwise 4, 5.
Why Not the Other Options:
- Cervical cancer (Option B): Does not typically present with adnexal masses or pleural effusion as initial manifestations 1
- Endometrial cancer (Option C): Rarely causes pleural effusion or significant ascites, and would not present with an adnexal mass as the primary finding 1
- "Uterine" cancer (Option D): This is too vague, but if referring to uterine sarcomas or other uterine malignancies, these do not typically present with adnexal masses 1
Critical Diagnostic Approach
The ACR guidelines emphasize that US imaging features including ascites, pleural effusions, and peritoneal/omental metastases are crucial for evaluating extent of disease in suspected ovarian malignancy 1. The presence of both ascites and pleural effusion with an adnexal mass creates a very high pretest probability for ovarian cancer in this demographic 2, 4, 5.
Important Caveat:
Even with elevated CA-125 and this classic presentation, definitive diagnosis requires histopathologic confirmation 3, 4, 5, 6. Benign conditions like Meigs syndrome can mimic ovarian cancer completely, including elevated tumor markers, but surgical resection with pathology is necessary to distinguish benign from malignant disease 4, 5, 6.