Can you explain the non‑contrast CT findings, particularly the 8.4 cm ovoid right pelvic lesion, and advise the appropriate next diagnostic or management steps?

CT Findings Explanation and Next Steps

Understanding the Key Finding

The 8.4 cm ovoid right pelvic lesion that has grown from 7.4 cm requires urgent contrast-enhanced imaging for definitive characterization, as non-contrast CT cannot adequately distinguish between benign and malignant etiologies. 1

The non-contrast study severely limits diagnostic accuracy because:

• Intravenous contrast is essential for detecting and characterizing pelvic masses, assessing enhancement patterns, and identifying malignant features 1
• Non-contrast CT cannot evaluate tissue vascularity, which is critical for distinguishing ovarian neoplasms from other pelvic pathology 1
• The documented size increase (from 7.4 cm to 8.4 cm) raises concern for a growing mass that requires immediate characterization 1

What the Current CT Shows

Normal Findings:

• No hydronephrosis or ureteral obstruction – this effectively rules out urinary tract pathology as the cause of the pelvic mass 2, 3
• No retroperitoneal lymphadenopathy (though evaluation is limited without contrast) 4
• No bowel obstruction or pericolonic inflammation 1

Concerning Finding:

• 8.4 cm right pelvic mass with documented growth – this size and growth pattern cannot be dismissed as physiologic 1
• The ovoid morphology suggests possible ovarian origin, but differential includes ovarian neoplasm, pedunculated fibroid, or other adnexal pathology 1, 5

Critical Next Steps

Immediate Imaging Required:

Order contrast-enhanced pelvic MRI without and with IV contrast as the next study. 1 This is superior to CT for several reasons:

• MRI provides 93% accuracy for distinguishing benign from malignant adnexal masses with gadolinium enhancement 1
• Diffusion-weighted imaging and gadolinium enhancement offer superior tissue characterization compared to CT 1
• MRI is specifically recommended for characterizing indeterminate pelvic findings when CT is inconclusive 1
• Avoids additional radiation exposure in a patient who may need serial imaging 1

Alternative if MRI Contraindicated:

CT pelvis with IV contrast (ideally CT abdomen and pelvis with IV contrast) if MRI cannot be performed 1

• Oral contrast should also be administered to optimize evaluation of bowel and peritoneum 1
• This allows assessment of enhancement patterns, peritoneal implants, and lymphadenopathy 1

Complementary Evaluation:

Transvaginal ultrasound with Doppler should be performed urgently 5

• Provides detailed characterization of ovarian masses with high accuracy 5
• Assesses vascularity patterns that help distinguish benign from malignant lesions 5
• Can identify specific features like dermoid cysts, endometriomas, or hemorrhagic cysts that MRI may further clarify 1, 5

Differential Diagnosis Considerations

Most Likely Etiologies (in order of concern):

1. Ovarian neoplasm (benign or malignant) – size >8 cm and documented growth mandate exclusion of malignancy 1
2. Pedunculated fibroid – can present as pelvic mass but typically shows characteristic MRI features 1
3. Ovarian torsion – less likely given lack of acute symptoms mentioned, but the size increases torsion risk 5
4. Endometrioma – possible but typically has characteristic imaging features on ultrasound/MRI 1

Red Flags Requiring Urgent Evaluation:

• Any acute pelvic pain warrants immediate ultrasound to exclude torsion, as masses >5 cm have increased torsion risk 5
• Fever or systemic symptoms would suggest infection/abscess requiring urgent intervention 1
• Hemodynamic instability would indicate possible rupture requiring emergency surgical consultation 5

Common Pitfalls to Avoid

• Do not assume a "probable" diagnosis from a prior study is correct – the documented growth changes the clinical picture and requires definitive characterization 1
• Do not delay imaging – an 8.4 cm pelvic mass with growth requires prompt evaluation regardless of symptoms 1
• Do not rely on non-contrast CT alone – this modality has severe limitations for pelvic mass characterization 1
• Do not forget tumor markers – serum CA-125 should be obtained if ovarian malignancy is in the differential, though imaging takes priority 1

Clinical Context Integration

The absence of hydronephrosis is reassuring that the mass is not causing urinary tract obstruction currently 2, 3, but the size and growth pattern demand urgent characterization to guide definitive management, which may include surgical resection depending on imaging findings and clinical context 1.