What is the likely diagnosis for a 52-year-old female with a golf ball-sized, firm, slightly movable lump on the lateral side of her right abdomen near the liver, no weight loss, normal bowel and urinary habits, and a family history of ovarian (cancer of the ovaries) and prostate (gland) cancer?

Differential Diagnosis and Immediate Management

This golf ball-sized, firm, slightly movable lateral abdominal mass in a 52-year-old woman with a family history of ovarian cancer requires urgent imaging with ultrasound followed by contrast-enhanced MRI or CT, and referral to a gynecologic oncologist if an adnexal mass is confirmed. The location near the liver on the lateral right abdomen could represent an ovarian/adnexal mass, hepatic lesion, or soft tissue tumor, and given her age, family history, and mass characteristics, malignancy must be excluded promptly.

Most Likely Diagnostic Considerations

Adnexal/Ovarian Mass (Primary Concern)

• A pelvic/adnexal mass can extend into the lateral abdomen and present as a palpable mass in this location, particularly if it is large or pedunculated 1
• The firm, slightly movable characteristics are consistent with either benign or malignant ovarian pathology 1
• Her age (52 years, perimenopausal/postmenopausal) and family history of ovarian cancer place her at elevated risk for ovarian malignancy 1
• Ovarian cancer is most prevalent in women in their sixth and seventh decades, with median age at diagnosis of 63 years 1

Hepatic Lesion

• The proximity to the liver raises consideration of a hepatic mass, though these are typically less mobile 1
• Hepatic adenomas, hemangiomas, or metastatic lesions could present in this location 1

Soft Tissue Mass

• A soft tissue tumor (lipoma, fibroma, or sarcoma) arising from the abdominal wall or retroperitoneum could present with these characteristics 2
• The slightly movable nature and firm consistency are consistent with various soft tissue pathologies 2

Immediate Diagnostic Workup

Initial Imaging

• Obtain pelvic and abdominal ultrasound immediately as the first-line imaging modality 1
• Ultrasound should include both transabdominal and transvaginal approaches to fully evaluate for adnexal pathology 1
• Color or power Doppler should be included to assess vascularity and differentiate solid from cystic components 1

Advanced Imaging

• If the mass is indeterminate on ultrasound, proceed with contrast-enhanced MRI of the pelvis and abdomen, which has superior soft-tissue discrimination and 91% accuracy for distinguishing benign from malignant masses 1
• CT with contrast is an alternative if MRI is not feasible, though it has lower specificity than MRI for adnexal mass characterization 1
• Chest imaging should be obtained to evaluate for metastatic disease if malignancy is suspected 1

Laboratory Evaluation

• Measure CA-125 immediately, as it is elevated in approximately 85% of advanced ovarian cancers 1, 3, 4
• Obtain complete blood count (CBC) and comprehensive metabolic panel including liver function tests 1, 3
• Consider additional tumor markers based on imaging findings: CEA (if mucinous histology suspected), LDH (for germ cell tumors), inhibin (for granulosa cell tumors) 3
• A CA-125/CEA ratio >25 favors ovarian origin over gastrointestinal origin 4

Critical Referral Criteria

Gynecologic Oncology Referral

• Refer immediately to a gynecologic oncologist if imaging reveals an adnexal mass with any concerning features 1, 5
• Referral is mandatory for O-RADS 4 (intermediate risk) or O-RADS 5 (high risk) lesions 5
• Elevated CA-125 in a postmenopausal woman with a pelvic mass, or CA-125 >200 units/mL in a premenopausal woman, warrants gynecologic oncology referral 5
• Published data demonstrate that primary assessment and surgical debulking by a gynecologic oncologist result in a survival advantage 1

Features Suggesting Malignancy on Imaging

• Solid components with enhancement 1
• Enhancing mural nodules or papillary projections 1
• Presence of ascites 1
• Bilateral masses 1
• Irregular borders or surface involvement 1

Common Pitfalls to Avoid

• Do not rely solely on CA-125 for diagnosis, as it can be elevated in many benign conditions (endometriosis, fibroids, pelvic inflammatory disease) and may not be elevated in early-stage ovarian cancer 3
• Do not assume a lateral abdominal mass is necessarily hepatic or abdominal wall in origin without excluding adnexal pathology, as large ovarian masses can extend superiorly 1
• Do not delay imaging or referral based on the absence of constitutional symptoms, as early ovarian cancer often presents without weight loss or systemic symptoms 1
• Avoid performing only transabdominal ultrasound without transvaginal imaging, as this may miss important adnexal pathology 1

Timeline for Action

• Imaging should be obtained within 1-2 weeks given the family history and mass characteristics 1, 5
• If imaging reveals concerning features, referral to gynecologic oncology should occur within 2 weeks 5
• The 2-day duration of awareness is reassuring that this is not an acute process requiring emergency intervention, but the evaluation should not be delayed 1