Clear cell papillary carcinoma of the liver: an unusual variant of peripheral cholangiocarcinoma

Recent Advances in Pathology of Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICCA) is a malignant epithelial neoplasm characterized by biliary differentiation within the liver. ICCA is molecularly heterogeneous and exhibits a broad spectrum of histopathological features. It is a highly aggressive carcinoma with high mortality and poor survival rates. ICCAs are classified into two main subtypes: the small-duct type and large-duct types. These two tumor types have different cell origins and clinicopathological features. ICCAs are characterized by numerous molecular alterations, including mutations in KRAS, TP53, IDH1/2, ARID1A, BAP1, BRAF, SAMD4, and EGFR, and FGFR2 fusion. Two main molecular subtypes-inflammation and proliferation-have been proposed. Recent advances in high-throughput assays using next-generation sequencing have improved our understanding of ICCA pathogenesis and molecular genetics. The diagnosis of ICCA poses a significant challenge for pathologists because of its varied morphologies and phenotypes. Accurate diagnosis of ICCA is essential for effective patient management and prognostic determination. This article provides an updated overview of ICCA pathology, focusing particularly on molecular features, histological subtypes, and diagnostic approaches.

Pathological, molecular, and clinical characteristics of cholangiocarcinoma: A comprehensive review

Cholangiocarcinomas are a heterogeneous group of highly aggressive cancers that may arise anywhere within the biliary tree. There is a wide geographical variation with regards to its incidence, and risk-factor associations which may include liver fluke infection, primary sclerosing cholangitis, and hepatolithiasis amongst others. These tumours are classified into intrahepatic, perihilar and distal based on their anatomical location. Morphologically, intrahepatic cholangiocarcinomas are further sub-classified into small and large duct variants. Perihilar and distal cholangiocarcinomas are usually mucin-producing tubular adenocarcinomas. Cholangiocarcinomas develop through a multistep carcinogenesis and are preceded by dysplastic and in situ lesions. While clinical characteristics and management of these tumours have been extensively elucidated in literature, their ultra-structure and tumour biology remain relatively unknown. This review focuses on the current knowledge of pathological characteristics, molecular alterations of cholangiocarcinoma, and its precursor lesions (including biliary intraepithelial neoplasia, intraductal papillary neoplasms of the bile duct, intraductal tubulopapillary neoplasms and mucinous cystic neoplasm).

Intrahepatic cholangiocarcinoma with clear cell type following laparoscopic curative surgery

Background

Intrahepatic cholangiocarcinoma (ICC) is the second most common malignancy of primary liver cancer. Among the several pathological types of ICC, only five cases of the clear cell type have been reported, including the one presented below. Here we report a unique case of clear cell type ICC following laparoscopic hepatectomy.

Case presentation

A 67-year-old woman had a history of hepatitis B virus. Computed tomography revealed a ring-like enhanced mass 35 mm in diameter at segment 7 in the early phase. The enhancement was prolonged to the late phase through the portal phase, while the shape was irregular. Ethoxybenzy magnetic resonance imaging revealed that the tumor had a low signal intensity on T1-weighted imaging and a high signal intensity on T2-weighted imaging. Diffusion-weighted images identified that the tumor had remarkably high signal intensity. Tumor enhancement was not detected throughout the tumor in the hepatocyte phase. Upon ICC diagnosis, a laparoscopic S7 subsegmentectomy was performed. The patient’s postoperative course was uneventful. An immunohistochemical examination revealed that the cells tested positive for cytokeratin 7 (CK7), CK19, and CD56 and negative for CK20, CD10, α-fetoprotein, thyroid transcription factor-1. At 2 years after surgery, the patient remains alive without recurrence.

Conclusions

Here we presented a case of clear cell ICC that was treated by laparoscopic hepatectomy. Immunological analysis, especially by CD56 and several CK markers, is helpful for diagnosing this disease.

Pathology of liver disease: advances in the last 50 years

Liver disease has been recognized in various forms for centuries. Incredible advances, however, have been made especially in the last 50 years, driven by improvements in histology, the development of immunostains, the development of high resolution imaging methods, improved biopsy and resection methods, and the emergence of the molecular era. With these tools, pathologists and their clinical and basic science colleagues moved from classifying liver disease using an observational, pattern-based approach to a refined classification of disease, one based on etiology for medical disease and tumor classification for neoplastic disease. Examples of liver specific diseases are used to illustrate these exciting advances. These impressive advances of the past provide the foundation for hope in the future, as liver pathology continues to play an important role in improving patient care through disease identification and classification and emerging roles in guiding therapy for cures.

Intrahepatic clear cell cholangiocarcinoma - An uncommon histologic subtype: case report and literature review

Clear-cell cholangiocarcinoma is a very uncommon variant of cholangiocarcinoma with a largely unknown natural history and prognosis. We report a case of a 51-year-old previously healthy woman presenting with a large liver nodule found on routine imaging. Needle biopsy of the lesion suggested a non-hepatocellular carcinoma. After extensive workup for other primary neoplasms, the patient underwent a partial hepatectomy. Histopathology was compatible with a moderately differentiated clear-cell cholangiocarcinoma. There was no evidence of liver disease in the remaining tissue. The patient underwent chemotherapy and remains in clinical remission after two years.

Clear cell hepatocellular carcinoma: origin, metabolic traits and fate of glycogenotic clear and ground glass cells

Clear cell hepatocellular carcinoma (CCHCC) has hitherto been considered an uncommon, highly differentiated variant of hepatocellular carcinoma (HCC) with a relatively favorable prognosis. CCHCC is composed of mixtures of clear and/or acidophilic ground glass hepatocytes with excessive glycogen and/or fat and shares histology, clinical features and etiology with common HCCs. Studies in animal models of chemical, hormonal and viral hepatocarcinogenesis and observations in patients with chronic liver diseases prone to develop HCC have shown that the majority of HCCs are preceded by, or associated with, focal or diffuse excessive storage of glycogen (glycogenosis) which later may be replaced by fat (lipidosis/steatosis). In ground glass cells, the glycogenosis is accompanied by proliferation of the smooth endoplasmic reticulum, which is closely related to glycogen particles and frequently harbors the hepatitis B surface antigen (HBsAg). From the findings in animal models a sequence of changes has been established, commencing with preneoplastic glycogenotic liver lesions, often containing ground glass cells, and progressing to glycogen-poor neoplasms via various intermediate stages, including glycogenotic/lipidotic clear cell foci, clear cell hepatocellular adenomas (CCHCA) rich in glycogen and/or fat, and CCHCC. A similar process seems to take place in humans, with clear cells frequently persisting in CCHCC and steatohepatitic HCC, which presumably represent intermediate stages in the development rather than particular variants of HCC. During the progression of the preneoplastic lesions, the clear and ground glass cells transform into cells characteristic of common HCC. The sequential cellular changes are associated with metabolic aberrations, which start with an activation of the insulin signaling cascade resulting in pre-neoplastic hepatic glycogenosis. The molecular and metabolic changes underlying the glycogenosis/lipidosis are apparently responsible for the dramatic metabolic shift from gluconeogenesis to the pentose phosphate pathway and Warburg-type glycolysis, which provide precursors and energy for an ever increasing cell proliferation during progression.

Cytopathologic, histopathologic, and immunohistochemical features of intrahepatic clear cell bile duct adenoma: a case report and review of the literature

Intrahepatic clear cell bile duct adenoma is extremely rare, with only 3 previous cases reported in the literature. The cause of cytoplasmic clearing in clear cell bile duct adenoma has not been previously investigated. Distinguishing clear cell bile duct adenoma from other clear cell tumors, particularly clear cell cholangiocarcinoma, can be challenging. Previous studies have shown loss of CD10 expression and focal CD56 expression in cholangiocarcinoma. Expressions of CD10 and CD56 have not been previously studied in clear cell bile duct adenoma. A 37-year-old morbidly obese woman was diagnosed with a 2.8 cm intrahepatic clear cell bile duct adenoma following segmental hepatic resection. Histochemical analysis of the tumor suggested the cause of cytoplasmic clearing in the neoplastic cells to be mucin and not glycogen or lipid. On immunohistochemical staining, the neoplastic cells demonstrated staining for CK7, CA 19-9, polyclonal CEA, CD10 (apical), CD56 (focal), and vimentin. Ki-67 highlighted less than 2% of tumor cell nuclei. This is the first report to study the etiology of cell clearing in clear cell bile duct adenoma. Expression of CD10 in clear cell bile duct adenoma may help distinguish clear cell bile duct adenoma from clear cell cholangiocarcinoma.

A case of intrahepatic clear cell cholangiocarcinoma

Intrahepatic clear cell cholangiocarcinoma is very rare - only 8 cases have been reported. A 56-year-old Japanese man with chronic hepatitis B infection was diagnosed with a 2.2 cm hepatocellular carcinoma on imaging, and hepatic segmentectomy was performed. Histopathologically, the tumor cells had copious clear cytoplasm and formed glandular structures or solid nests. These pathological findings suggested the tumor was a clear cell variant of intrahepatic cholangiocarcinoma. Particular stains and radiological images suggested that the cause of the clear cell change had been glycogen, not mucin nor lipid. On immunohistochemical staining, cytokeratin (CK) 7 and CK19 were positive, whereas CK20 was negative. Vimentin was detected on the cell membranes, and CD56 was focally positive. The patient was given adjuvant chemotherapy and is currently free from the tumor 7 mo postoperatively. Careful follow-up with adequate postoperative supplementary chemotherapy is necessary because the characteristics of this type of tumor are unknown.

Intrahepatic Clear Cell Cholangiocarcinoma

Clear cell cholangiocarcinoma is a very unusual variant of peripheral bile duct carcinoma. We present 3 cases on which we performed a broad spectrum of immunohistochemical analysis. The tumors showed a glandular and trabecular growth pattern with abundant desmoplastic stroma and clear cell change of about 80% of the tumor cells. Positive expression of CK7 indicated a cholangiocellular origin. A primary hepatocellular carcinoma and metastatic clear cell tumors of the kidney, gastrointestinal tract, and the thyroid gland were excluded by absence of CK20, CD10, HepPar1, and TTF1. No mucin could be detected within the cytoplasm of the clear cells. Electronmicroscopy revealed only a few glycogen granula, but numerous cytoplasmic lipoid vacuoles as a possible explanation for the clear cell phenotype. All 3 tumors exhibited positive expression of CD56 (NCAM) in a significant amount of the clear cells. Beside the clear cell component, one tumor also showed an adenocarcinomalike and a well-differentiated tubular component. CD56 expression was detected in all 3 tumor areas. This report of 3 cases demonstrates that clear cell cholangiocarcinomas are not only of unusual histomorphology. They also show CD56 expression which is a very uncommon finding for intrahepatic cholangiocarcinomas. As CD56 expression is also found in reactive bile ducts and bile duct adenomas, one may speculate that these rare neoplasms may originate from reactive bile ducts or cholangiomatous lesions.

CD56 expression aids in the differential diagnosis of cholangiocarcinomas and benign cholangiocellular lesions

CD56 (neuronal cell adhesion molecule, N-CAM) has been reported in neuroendocrine tumours and as a marker of reactive biliary epithelial cells. However, up to date, it is not used to distinguish malignant from non-malignant biliary lesions. In this study, we systematically examined CD56 expression on 98 tumours arising from the biliary tree as well as intrahepatic conditions with reactive neoductules. When neuroendocrine carcinomas are excluded, only 4 of 32 (12.5%) cholangiocarcinomas expressed CD56, 2 of which showed clear cell morphology. Reactive bile ductules adjacent to cirrhotic nodules as well as in focal nodular hyperplasia were CD56 positive. Twelve of 17 (70.5%) bile duct adenomas were CD56 positive, whereas von Meyenburg complexes expressed CD56 only very focally in less than 5% of lesional cells. Bile duct cysts were negative for CD56 with the exception of focally interspersed neuroendocrine cells, similar to that seen in segmental bile ducts. Thus, if van Meyenburg complexes are excluded, CD56 can be used to differentiate intrahepatic non-neoplastic from neoplastic proliferations, which is a helpful diagnostic tool in small liver biopsies.

Atypical bile duct adenoma, clear cell type: a previously undescribed tumor of the liver

A variable proportion of bile duct adenomas of the liver are still confused with metastatic well-differentiated adenocarcinoma by surgeons and pathologists. We present here three examples of previously undescribed primary hepatic bile duct tumors that were composed almost entirely of clear cells that closely mimicked metastatic renal cell carcinoma. They were interpreted as atypical bile duct adenomas and occurred in two males and one female whose ages ranged from 25 to 64 years. All three tumors were incidental findings and measured from 0.8 to 1.1 cm. The clear neoplastic cells showed mild nuclear atypia and no mitotic activity. They were arranged in tubules and nests that focally infiltrated the hepatic parenchyma. For comparison, a case of clear cell cholangiocarcinoma and 13 conventional bile duct adenomas were examined. The clear cell cholangiocarcinoma was larger (6.0 cm) and had the tubular pattern of conventional cholangiocarcinoma and an abundant desmoplastic stroma. The clear cells of this tumor exhibited greater nuclear atypia and increased mitotic activity. All three atypical bile duct adenomas expressed cytokeratin (CK) 7, p53 protein, epithelial membrane antigen (EMA), and carcinoembryonic antigen (CEA); they were negative for CK20, vimentin, Hep Par 1, chromogranin, and prostatic specific antigen (PSA) and exhibited less than 10% of Ki-67-positive nuclei. One atypical bile duct adenoma displayed luminal immunoreactivity for villin. With the exception of Ki-67 reactivity, the 13 conventional bile duct adenomas and the clear cell cholangiocarcinoma had essentially a similar immunohistochemical profile as that of the atypical clear cell bile duct adenomas. The absence of an extrahepatic primary tumor, the histologic features, the immunohistochemical profile, and the fact that all patients are symptom-free 2 months to 18 years after wedge liver biopsy support the interpretation of atypical clear cell bile duct adenoma. The differential diagnosis with clear cell hepatocellular carcinoma and metastatic clear cell carcinomas is discussed.

Clear cell carcinoma of the liver: a comparative immunohistochemical study with renal clear cell carcinoma

Morphologic differentiation of clear cell hepatocellular carcinoma (HCC-CC) from clear cell renal carcinoma (RCC-CC) may not be possible without the aid of immunohistochemical stains. We performed a battery of immunohistochemical stains on 10 previously diagnosed HCC-CCs, and 10 RCC-CCs, in order to determine which single or combination of immunostains would be most useful in diagnosis. We concluded that a positive Hepatocyte immunostain (DAKO) is sufficient for a diagnosis of HCC-CC if enough tissue is available. This immunostain distinguishes HCC-CC from other clear cell malignancies with sensitivity of 90% and specificity of 100%, when biopsy material is adequate. Other tests were much less sensitive, although several had specificity of 100%. A negative immunostain does not exclude the diagnosis of HCC-CC (negative predictive value 91%, especially in small biopsy material) and should be followed by additional immunostains such as pCEA for demonstration of tumor canaliculi, ubiquitin for Mallory bodies, and several epithelial cell markers that are typically positive in RCC-CC (epithelial membrane antigen, Leu M-1, pancytokeratin) and negative in HCC-CC.

Peripheral Clear Cell Cholangiocarcinoma: A Rare Histologic Variant

We present the case of a 50-year-old diabetic male who underwent open cholecystectomy for acute gangrenous cholecystitis. At the time of exploration, a 1.5-cm mass was found peripherally in the right lobe of his liver, and an incisional biopsy was performed. Microscopic examination revealed a distinct overgrowth of clear cells in an acinar pattern, with tumor cells emerging directly from bile ducts. The tumor cells were periodic acid-Schiff reactive and diastase resistant, indicating the presence of mucin. No bile canaliculi were demonstrated by immunostaining with carcinoembryonic antigen. CT scans of the chest and abdomen were otherwise normal. Based on these microscopic, immunohistochemical, and clinical data, a diagnosis of clear cell cholangiocarcinoma was established. The patient later underwent reexploration and generous hepatic wedge resection. He did well postoperatively and is free of disease after 12 months.