Can unroofing of a hepatic cyst in a middle-aged to older adult woman with a Mucinous Cystic Neoplasm (MCN) of the liver cause peritoneal carcinomatosis?

Risk of Peritoneal Carcinomatosis from Unroofing of Hepatic Mucinous Cystic Neoplasm

Yes, unroofing (fenestration) of a hepatic mucinous cystic neoplasm carries a significant risk of recurrence and potential malignant transformation, though direct peritoneal carcinomatosis from the initial unroofing procedure itself is not well-documented in the literature. The primary concern is that incomplete excision leaves residual neoplastic tissue with ongoing malignant potential rather than immediate peritoneal seeding.

Why Unroofing is Inadequate and Dangerous

Fenestration or unroofing is associated with high recurrence rates and is considered inadequate treatment for MCNs of the liver 1, 2. The fundamental problem is that unroofing leaves behind the cyst wall containing the mucin-producing epithelium and ovarian-like stroma—the very tissue with malignant potential 1.

Evidence of Poor Outcomes After Incomplete Resection

• Recurrence rates after incomplete resection are high (0-26% in reported series), though this may overestimate true rates due to reporting bias 1
• Two documented cases in the research literature showed early recurrence after unroofing, with one patient developing volumetric enlargement and new satellite cysts requiring subsequent left hepatectomy 3
• Another series documented three patients who had percutaneous drainage or operative deroofing before referral, all requiring definitive surgical resection 4

The Malignant Transformation Risk

The critical issue is ongoing malignant potential rather than immediate peritoneal spread:

• MCNs carry a 3-6% risk of invasive carcinoma, typically found in older patients 1, 5
• Approximately one-third of reported MCNs are associated with invasive adenocarcinoma in pancreatic series, though hepatic MCNs may have lower rates 1
• Malignancy is most commonly found within mural nodules >1 cm 1
• When invasive carcinoma is present, 5-year survival drops to 50-60% compared to nearly 100% for completely resected non-invasive MCNs 1

Current Standard of Care

Complete surgical resection with free margins is mandatory for suspected MCNs—either by formal hepatic resection or enucleation 2. The 2022 EASL guidelines provide the most authoritative recommendation:

• Surgical resection is the gold standard for suspected MCNs of the liver, and complete resection should be aimed for (Level of Evidence 3, strong recommendation, 100% consensus) 1
• Acceptable surgical options include formal hepatic resection and enucleation with free margins 2
• After complete resection with free margins, recurrence rates are very low, and malignant transformation in initially benign lesions is rare 1, 2

Clinical Management After Prior Unroofing

For a patient who has already undergone unroofing:

Immediate Assessment Required

• Obtain high-quality MRI to assess for residual or recurrent disease, as MRI has 94-98% specificity when multiple worrisome features are present 6, 5
• Look specifically for thick septations, nodularity, upstream biliary dilatation, and mural nodules >1 cm 1
• Check tumor markers (CEA and CA 19-9), which may be elevated particularly if invasive carcinoma has developed 1, 6

Definitive Management Strategy

• If any residual cystic tissue is present, proceed to complete surgical resection with formal hepatic resection or enucleation with free margins 2
• Intraoperative frozen section has a high false-negative rate (4/6 in one series), so do not rely on it to rule out MCN 7
• Even if imaging appears clear, close surveillance is mandatory with periodic imaging and tumor markers 2

Surveillance Protocol

• Regular imaging surveillance is prudent with clinical evaluation, periodic imaging, and tumor markers (CA19-9, CEA) 2
• The presence of malignancy at initial resection is the most significant factor associated with poorer outcomes 1, 2

Critical Pitfalls to Avoid

• Do not assume a "simple cyst" diagnosis without MRI characterization, as MCNs occur predominantly in middle-aged women (80-85% female) and can be mistaken for benign cysts 2, 6
• Do not perform percutaneous drainage or aspiration, as this is inadequate treatment and delays definitive management 4
• Do not rely on the absence of symptoms, as 86% of MCNs are symptomatic but 14% are incidentally discovered 1
• Avoid mistaking hemorrhagic septations for malignancy, but recognize that true thick septations and nodularity indicate MCN requiring resection 5

Bottom Line

While direct peritoneal carcinomatosis from the unroofing procedure itself is not the primary documented complication, the real danger is leaving behind neoplastic tissue with ongoing malignant potential that can progress to invasive carcinoma over time. The patient requires immediate MRI assessment and strong consideration for completion resection if any residual cystic tissue remains, as this is the only way to eliminate the risk of malignant transformation and achieve cure.