Discovery of diffuse biliary microhamartomas during liver procurement

Authors


Donor availability limits the application of liver transplantation. As the demand for transplantation has increased, strategies to increase donor utilization have gained popularity.1, 2 Extended criteria donor (ECD) liver allografts are outside traditional donor criteria for liver transplantation. Although these organs offer immediate expansion of the donor pool, transplantation of ECD liver allografts may increase potential short-term and long-term risk to the recipient. Herein we report utilization of an ECD liver with an unusual finding

Abbreviation

ECD, extended criteria donor.

The donor was a 43-year-old deceased male with a history of hepatitis C and intravenous drug abuse who progressed to brain death after a cardiac arrest due to presumed drug overdose. The patient had a past medical history of tuberculosis 15 years earlier, but further details were unavailable. Laboratory studies were normal except for a mild elevation in serum aminotransferases (aspartate aminotransferase, 81; alanine aminotransferase, 142). The patient's next of kin consented to organ donation.

Abdominal exploration during organ procurement revealed multiple diffuse, small, white-yellow nodules, which were more numerous in the right lobe (Fig. 1A). The lesions were subcapsular and measured approximately 0.5 cm in diameter. There were also several small cystic lesions. No other masses were found in the liver. We performed a complete exploration of the thorax and abdomen to rule out sources of malignancy or evidence of extrahepatic tuberculosis. No other abnormalities were found. Frozen section histology of the lesions identified them as biliary hamartomas (von Meyenburg complexes; Fig. 2).

Figure 1.

Liver allograft after procurement. Multiple small, white-yellow nodular lesions.

Figure 2.

Hematoxylin-eosin (×10). Bile duct microhamartoma (von Meyenburg complex) consisting of circumscribed fibrous areas containing irregularly dilated duct structures.

The liver was procured and transplanted into a 53-year-old man with hepatitis C and high-grade, poorly differentiated hepatocellular carcinoma that had recurred after resection. The patient's operative course and postoperative course were unremarkable. The patient is alive and well with normal liver function and no evidence of recurrence at 1 year post transplant.

Bile duct hamartomas or von Meyenburg complexes are rare benign tumors of the liver and are generally found incidentally at autopsy in 0.69% to 5.6% of cases.3–5 They are thought to be congenital bile duct malformations due to the failure of embryonic involution.3 They appear as gray-white, sometimes black, nodular lesions measuring up to 1 cm in diameter and are disseminated at the surface of both lobes of the liver.4, 6 They are easily confused with metastatic disease of the liver.6 Some imaging signs may differentiate these lesions from metastatic disease. On ultrasound, they appear as small hypoechoic or hyperechoic lesions with comet-tail echoes.5 On a computed tomography scan, they remain hypodense after contrast enhancement. Magnetic resonance imaging findings are hypointensity on T1-weighted images and hyperintensity on T2-weighted images.5–8 Magnetic resonance cholangiopancreatography images have been suggested to be more sensitive than computed tomography or magnetic resonance imaging, showing irregularly delineated hyperintense nodules. Although biliary microhamartomas are in continuity with the biliary, this is not apparent on imaging studies. If the diagnosis is still unclear, a biopsy should be performed that will identify these lesions histologically as well-defined, irregular, round, dilated, tortuous branching bile ducts. If this entity is encountered during organ donation, frozen section evaluation should be performed to verify the diagnosis.

Although the history of tuberculosis and the gross appearance of these lesions concerned us during the procurement, the literature shows that hepatic tuberculosis is extremely rare in the absence of disseminated abdominal tuberculosis.9

The rarity of diffuse biliary microhamartomas makes them difficult to study in a systematic fashion. Although they are usually benign entities, there have been several case reports of cholangiocarcinoma in association with multiple biliary microhamartomas.10, 11 Oncologic surveillance will include regularly obtained carbohydrate antigen 19-9 antigen assays because of the rare association of cholangiocarcinoma with biliary microhamartomas. Additionally, there may be a theoretical risk for future development of symptomatic polycystic disease as diffuse biliary microhamartomas may be considered part of the spectrum of adult polycystic liver disease.12 These lesions may be at risk to undergo gradual cystic dilation. It is likely that this process is facilitated by estrogen because most polycystic patients that require liver transplantation are female. In this particular case, the risk appears to be negligible as both donor and recipient were male.

To date, there has been no literature on the use of donor livers with this finding. We suspect that the natural history of these lesions in the transplant recipient will be benign as it usually is in the host. We believe these small additional risks are warranted, especially when the indication for transplantation is hepatocellular carcinoma.

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