Wilson Tsui

Hepatic angiomyolipoma - A clinicopathologic study of 30 cases and delineation of unusual morphologic variants

Hepatic angiomyolipoma (AML) is frequently misdiagnosed. HMB-45 is a promising immunomarker for this tumor that leads to recognition of some AMLs with unusual morphology. The purpose of this collaborative study is to better define the morphologic variations of AML. Thirty AMLs were examined, including four biopsy specimens and two fine-needle aspirates. The diagnosis was confirmed by the presence of HMB-45-positive myoid cells. Almost half the cases were originally misdiagnosed as carcinomas or sarcomas. There was marked female predominance (25:5), and the mean age was 48.7 years (range 29-68). Three patients (10%) had evidence of tuberous sclerosis and all had renal AML. According to the line of differentiation and predominance of tissue components, the tumors was subcategorized into mixed, lipomatous (> or = 70% fat), myomatous (< or = 10% fat), and angiomatous type. The mixed type was the most common (11 resected cases), comprising sheets of epithelioid muscle cells admixed with islands of adipocytes, abnormal vessels, and frequently, hematopoietic cells. Six tumors (including three from biopsy specimens) were heavily fatty and showed predominantly adipocytes with epithelioid and short spindle myoid cells webbed between fat cells. Of 10 myomatous AMLs, five tumors showed a pure sinusoidal trabecular pattern and comprised mainly epithelioid cells. Typically, mature adipocytes were absent or scanty, but fat was seen as fine droplets within cytoplasm or as occasional large globules in sinusoids. Pelioid and inflammatory pseudotumor-like patterns were identified focally. Regarding cellular features of the myoid cells, most of the epithelioid cells were either eosinophilic or clear with spiderweb cell morphology. Three AMLs showed an almost purely oncocytic appearance with scanty fat. Large pleomorphic epithelioid cells existed as small foci. Spindle cells arranged in long fascicles were uncommon. D-PAS-positive globules were common around pelioid areas. Brown pigments with staining characteristics of hemosiderin and/or melanin were noted. In conclusion, we propose HMB-45-positive myoid cells as the defining criterion of hepatic AML, which is a tumor capable of dual myomatous and lipomatous differentiation and melanogenesis. Because of its protean morphologic appearance, recognition of the various variant patterns and cell types is important for a correct diagnosis, assisted by immunohistochemical confirmation with HMB-45. Trabecular and oncocytic cell tumors appear to stand out as distinctive subtypes.

Hepatic ‘stem cell’ malignancies in adults: four cases

Aims:  Combined hepatocellular/cholangiocarcinomas have been explained by some investigators as bidirectional differentiation of neoplastic progenitor cell populations. The presence of hepatic progenitor cells has now been confirmed in humans, though whether they can give rise to malignant tumours has not been confirmed. We report four cases of small tumours identified in livers with features of chronic hepatitis which may suggest a role for malignant transformation of hepatic stem cells in hepatic malignancies.

Biliary intraepithelial neoplasia: an international interobserver agreement study and proposal for diagnostic criteria

Cholangiocarcinoma of the intrahepatic and extrahepatic bile ducts develops through a multistep histopathologic sequence. Premalignant or non-invasive neoplastic lesions of bile ducts have been historically called biliary dysplasia or atypical biliary epithelium. To this date, no standard terminology or classification system has been offered for these lesions. In 2005, a conceptual framework and diagnostic criteria for biliary intraepithelial neoplasia (BilIN) were proposed using the livers of patients with hepatolithiasis. We report herein an international interobserver agreement study on the diagnosis of biliary non-invasive neoplastic lesions with the goal to obtain a consensus on the terminology and grading. Seventeen pathologists from the United States, Europe and Asia participated in this study. They shared a digital file containing histological pictures of 30 foci of non-invasive neoplastic lesions selected from the biliary system of patients suffering from primary sclerosing cholangitis, choledochal cyst or hepatolithiasis. In the criteria, we proposed in 2005, BilIN was classified into three categories based on the degree of atypia: BilIN-1, BilIN-2 and BilIN-3. In this study, consensus was reached for the terminology of BilIN and the three-grade classification system. Interobserver agreement on the diagnosis was moderate (κ-value=0.45). On the basis of the suggestions and opinions obtained from the 17 participants, the original criteria for BilIN were revised. We now propose a new consensus classification of BilIN that may assist in allowing a more uniform terminology for the diagnosis of biliary non-invasive neoplastic lesions. This classification should help to advance clinical and research applications.

Hep Par 1 and selected antibodies in the immunohistological distinction of hepatocellular carcinoma from cholangiocarcinoma, combined tumours and metastatic carcinoma.

To examine the usefulness of Hep Par 1 together with selected antibodies in the separation of hepatocellular carcinoma (HCC) from cholangiocarcinoma (CC), combined tumours (HCC‐CC) and metastatic carcinoma.

Application of a new histological staging and grading system for primary biliary cirrhosis to liver biopsy specimens: Interobserver agreement

Recently the authors proposed a new staging and grading system for primary biliary cirrhosis (PBC) that takes into account necroinflammatory activity and histological heterogeneity. Herein is proposed a convenient version of this system. Scores for fibrosis, bile duct loss, and chronic cholestasis were combined for staging: stage 1, total score of 0; stage 2, score 1–3; stage 3, score 4–6; and stage 4, score 7–9. Cholangitis activity (CA) and hepatitis activity (HA) were graded as CA0–3, and HA0–3, respectively. Analysis of interobserver agreement was then conducted. Digital images of 62 needle liver biopsy specimens of PBC were recorded as virtual slides on DVDs that were sent to 28 pathologists, including five located overseas. All participants were able to apply this version in all 62 cases. For staging, kappa was 0.385 (fair agreement) and the concordance rate was 63.9%. For necroinflammatory activity, the kappa and concordance rate were 0.110 (slight agreement) and 36.9% for CA, and 0.197 (slight agreement) and 47% for HA, respectively. In conclusion, this new staging and grading system for PBC seems to be more convenient and practical than those used at present, but more instruction and guidance are recommended for the grading of necroinflammatory activity in practice.

Biliary adenofibroma. A heretofore unrecognized benign biliary tumor of the liver

Benign biliary tumors of the liver are uncommon. In this report, we describe a distinctive biliary tumor of 7-cm diameter occurring in the right lobe of the liver of a 74-year-old Chinese woman. The lesion, characterized by a complex tubulocystic nonmucin secreting biliary epithelial and an abundant fibroblastic stromal components, is distinct from other well-recognized biliary lesions. A number of unusual features are focally present, namely, intraluminal bile concretions, apocrine-like epithelial change, acute inflammation, and granuloma. The tumor shows a striking resemblance to Meyenburgs complex (MC), but the large size of the lesion and the absence of any typical MC in the background liver are exceptional for the latter. Its expansile growth, possession of mitoses, and foci of epithelial tufting and cellular atypia favor a neoplastic process. Previous reported cases of adenomatous neoplastic transformation of MC are dissimilar. We therefore conclude that this is a hitherto unrecognized biliary tumor that may be yet another neoplastic form of MC and propose the designation biliary adenofibroma. The course appears benign, but malignant epithelial transformation may supervene if the lesion is left untreated.

Hepatolithiasis and the Syndrome of Recurrent Pyogenic Cholangitis: Clinical, Radiologic, and Pathologic Features

Primary hepatothiasis (HL) and recurrent pyogenic cholangitis (RPC) are two terms describing the different aspects of the same disease, with HL emphasizing the pathologic changes and RPC emphasizing the clinical presentation and suppurative inflammation. It is predominantly a disease of the Far East. In the 1960s, it was the third most common cause of emergency abdominal surgery at a university hospital in Hong Kong. Thereafter, its incidence has decreased considerably, possibly due to improved standards of living and Westernized diet. Clinically, patients may present acutely with recurrent bacterial cholangitis and its possible complications, such as liver abscess and septicemic shock, or with chronic complications, such as cholangiocarcinoma. Pathologically, it is characterized by pigmented calcium bilirubinate stones within dilated intrahepatic bile ducts featuring chronic inflammation, mural fibrosis, and proliferation of peribiliary glands, without extrahepatic biliary obstruction. Episodes of suppurative inflammation cumulate in sclerosing cholangitis of peripheral ducts and parenchymal fibrosis resulting from collapse and scarring. Mass-forming inflammatory pseudotumor and neoplasms like intraductal papillary neoplasms and cholangiocarcinoma are increasingly recognized complications. Modern imaging techniques allow definitive diagnosis, accurate assessment for treatment planning, and detection of complications. A multidisciplinary team approach (interventional endoscopist, interventional radiologist, hepatobiliary surgeon, and intensivists) is important for optimal patient outcome.

Expression of MUC1 and MUC2 and carbohydrate antigen Tn change during malignant transformation of biliary papillomatosis

Expression of MUC1 and MUC2 and carbohydrate antigen Tn change during malignant transformation of biliary papillomatosis

Primary hepatolithiasis, recurrent pyogenic cholangitis, and oriental cholangiohepatitis: a tale of 3 countries.

Primary hepatolithiasis (HL), recurrent pyogenic cholangitis, and oriental cholangiohepatitis are terms commonly used in Japan, Hong Kong, and Korea respectively, and describing the different aspects of the same disease, with “HL” indicating the pathologic changes, “recurrent pyogenic cholangitis” emphasizing the clinical presentation and suppurative inflammation, and “oriental cholangiohepatitis” highlighting its ethnic preference and mysterious nature. HL is predominantly a disease of the far east and shows great regional differences in the incidence and the type of intrahepatic stones. Pathologically, it is characterized by pigmented calcium bilirubinate stones within dilated intrahepatic bile ducts featuring chronic inflammation, mural fibrosis, and proliferation of peribiliary glands, without extrahepatic biliary obstruction. Episodes of suppurative inflammation cumulate in sclerosing cholangitis in peripheral ducts and parenchymal fibrosis from scarring and collapse. Mass-forming inflammatory pseudotumor and neoplasms-like intraductal papillary neoplasms and cholangiocarcinoma are increasingly recognized complications. Bacterial infection and dietary factors are believed to be important in the formation of pigment stones within intrahepatic bile ducts, whereas parasitic infestation is likely coincidental. With improvement of environmental conditions and westernization of diet, the incidence of pigment stones has decreased. At the same time, cholesterol stones with milder clinical manifestations and pathologic changes are increasingly recognized, and for which stone dissolution therapy can be considered. Understanding the underlying pathology avoids confusion with other diseases more prevalent in the western world, and allows correct selection of the appropriate treatment.

Hepatic cavernous hemangioma: underrecognized associated histologic features

Abstract: Background/Aims: Cavernous hemangiomas (CH) are typically described as solitary, well‐circumscribed lesions and are reported to have a distinct fibrous interface. This study describes underrecognized histological changes of large hepatic hemangiomas that contradict this long‐standing view.