Biliary hamartomata or metastatic cancer: A diagnostic challenge

October 22, 2007
Surgical Rounds®, October 2007, Volume 0, Issue 0

Reza F. Saidi,Sumet Silapaswan, Stephen G. ReMine, Michael J. Jacobs,

Reza F. Saidi, MD

Chief Resident

Department of Surgery

Providence Hospital and

Medical Centers

Southfield, MI

Sumet Silapaswan, MD

Consultant Surgeon

Department of Surgery

Providence Hospital and

Medical Centers

Southfield, MI

Stephen G. ReMine, MD

Consultant Surgeon

Department of Surgery

Providence Hospital and

Medical Centers

Southfield, MI

Michael J. Jacobs, MD

Consultant Surgeon

Department of Surgery

Providence Hospital and

Medical Centers

Southfield, MI

Clinical Associate

Professor

Wayne State University

School of Medicine

Detroit, MI

Introduction: Biliary hamartomata are benign hepatic lesions that can mimic metastases on imaging studies and during intraoperative exploration. As a result, these obscure lesions may cause diagnostic confusion and subsequent alterations in planned management, particularly with regard to synchronous metastatic liver disease.

Results and discussion: The authors report four cases of biliary hamartomata, highlighting their experience with these lesions, and describe the spectrum of findings that may be encountered in patients with this condition.

Conclusion: Although uncertainty may remain, biliary hamartomata that have been identified as clinically or histologically suspicious or indeterminate should be treated as malignant neoplasms, whereas asymptomatic biliary hamartomata can be observed.

Biliary hamartomata are rare benign lesions that were first described in 1918 by von Meyenburg.1 Typically, these biliary malformations form cystic structures of various sizes within an array of architectural distortion.1,2 These lesions have been shown to mimic malignant tumors, making them difficult to diagnose, particularly in the presence of concomitant metastatic disease.1-4 We report our experience with biliary hamartomata and coexistent malignant lesions and describe an array of clinical scenarios that can confound surgical management.

Case reports

Case 1—

A diagnosis of metachronous metastatic colon cancer to the liver was made in an 89-year-old woman following a previous partial colectomy. A preoperative computed tomography (CT) scan showed multiple cystic and nodular lesions within the liver that were thought to represent colorectal metastases. A laparotomy was performed, and the liver was found to contain numerous nodular lesions suggestive of metastatic involvement. Wedge resections were performed on two lesions, and pathology evaluations were consistent with biliary hamartomata (Figure 1). The patient was disease-free 2 years postoperatively, and the additional liver lesions have remained stable.

Case 2—

A 62-year-old man was scheduled to undergo pancreaticoduodenectomy for carcinoma of the head of the pancreas subsequent to neoadjuvant therapy. A preoperative CT scan confirmed tumor response and showed no evidence of metastasis. Upon abdominal exploration, multiple superficial nodules within the liver were identified and biopsied. The operation was terminated because of indeterminate frozen-section pathology and the high probability of metastatic disease. The final pathology was consistent with biliary hamartomata (Figure 2), and the patient subsequently underwent a curative pancreatic resection.

Case 3—

A 64-year-old woman presented with painless obstructive jaundice. The preoperative workup included a CT scan of the abdomen and pelvis and endoscopic ultrasonography. Each test confirmed the presence of a 2.5-cm mass in the head of the pancreas without evidence of metastases or locally advanced disease. Upon abdominal exploration, multiple superficial white nodules were identified within the liver (Figure 3). Frozen-section pathology demonstrated biliary hamartomata. The patient was deemed inoperable because of vascular invasion and was referred for adjuvant therapy.

Case 4—

A 44-year-old man presented to his primary care physician for the evaluation of mild generalized lymphadenopathy. An infectious process was suspected, and the patient was started on antibiotics. A CT scan of the patient's abdomen revealed multiple, ill-defined, solid lesions within the hepatic parenchyma (Figure 4). A laparoscopic liver biopsy to look for concomitant intra-abdominal pathology targeted the most prominent lesions. The final histopathology revealed biliary hamartomata. The patient was observed, and the lymphadenopathy subsequently resolved without additional therapy.

Discussion

Biliary hamartomata are rare benign tumors of the liver that exhibit abnormal histological features, such as ductules that contain a single layer of cuboidal epithelium surrounded by a fibrous stroma. The pathogenesis of these lesions is the result of arrested development and remodeling of the small, peripheral intrahepatic biliary ducts.2 Biliary hamartomata are thought to reside on the spectrum of congenital hepatic fibrosis and may be associated with other congenital diseases, including hepatic fibrosis, polycystic kidney disease, and Caroli's disease.2 Grossly, these lesions are usually multiple (von Meyenburg complex) and may be dispersed throughout the liver. A biliary hamartoma may also appear as a single subcapsular or parenchymal nodule that measures less than 5 mm. Macroscopically, biliary hamartomata are whitish-gray and range from 5 to 10 mm in diameter.1,2 The bile ducts within these lesions are also variable, ranging from narrow to very dilated.1,2 Although the risk of malignant conversion is low, malignant transformation into cholangiocarcinoma has been reported.5

In our experience, biliary hamartomata can create diagnostic confusion and uncertainty. In the cases we reported, the surgical care and prognosis of patients was altered considerably after the condition was properly diagnosed. The variable reported incidence of these macroscopic lesions adds to the diagnostic confusion. The reported incidence in autopsy series ranges from 0.69% in cases of macroscopic examination to 2.8% in microscopic surveys.1,2 The true incidence of biliary hamartomata, particularly in the presence of concomitant intra-abdominal malignancy, is unknown. Since most of these lesions are asymptomatic and do not produce laboratory abnormalities, many may go undetected.

While histologic analysis provides the most accurate diagnosis, ultrasonography, CT scanning, and magnetic resonance imaging (MRI) also may show these lesions. Biliary hamartomata may appear hypoechoic, hyperechoic, or as a mixed echotexture on ultrasonography. On CT scanning, the lesions look like hypodense nodules of variable enhancement and size. Biliary hamartomata often uniformly measure less than 1 cm, compared with the sporadic sizes observed with metastatic disease. Based on CT scanning alone, the radiographic differential diagnosis could include metastases, simple hepatic cysts, parasitic or nonparasitic cysts, Caroli's disease, cystadenoma, or liver abscess.4 MRI is not helpful in determining the diagnosis, because biliary hamartomata are hypodense on T1-weighted images and hyperdense on T2-weighted images.3 Based on our experience and that of others, ultrasonography, CT scanning, and MRI studies are unreliable and may further complicate reaching the correct diagnosis.3,4 The definitive diagnosis of biliary hamartomata should be based solely on tissue sampling.

Conclusion

The diagnostic confusion that biliary hamartomata cause may result in the need to alter treatment for patients who are being operated on for intra-abdominal pathology that appears malignant. Although improved imaging techniques and innovative diagnostic modalities are inevitable, we think that these seemingly harmless lesions will continue to present a diagnostic challenge and require modification of patient therapy. We advocate tissue confirmation of any hepatic lesions that appear suspicious. Any indeterminate pathology should be treated as a malignant process until proven otherwise. Asymptomatic biliary hamartomata may be observed due to the well-known benign nature of these lesions.

Disclosure

The authors have no relationship with any commercial entity that might represent a conflict of interest with the content of this article and attest that the data meet the requirements for informed consent and for the Institutional Review Boards.

References

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  2. Principe A, Lugaresi ML, Lords RC, et al. Bile duct hamartomas: diagnostic problems and treatment. Hepatogastroenterology. 1997;44(16):994-997.
  3. Cheung YC, Tan CF, Wan YL, et al. MRI of multiple biliary hamartomas. Br J Radiol. 1997;70(833):527-529.
  4. Lev-Toaff AS, Bach AM, Wechsler RJ, et al. The radiologic and pathologic spectrum of biliary hamartomas. AJR Am J Roentgenol. 1995;165(2):309-313.
  5. Orii T, Ohkohchi N, Sasaki K, et al. Cholangiocarcinoma arising from preexisting biliary hamartoma of liver—report of a case. Hepatogastroenterology. 2003;50(50):333-336.