Jia-Huei Tsai

Morphological subclassification of intrahepatic cholangiocarcinoma: etiological, clinicopathological, and molecular features

On the basis of morphological features, we subclassified 189 intrahepatic cholangiocarcinomas into two subtypes: bile duct and cholangiolar. The cholangiolar type is composed of cuboidal to low columnar tumor cells that contain scanty cytoplasm. The bile duct type is composed of tall columnar tumor cells arranged in a large glandular pattern. In this study, 77 (41%) tumors were classified as the cholangiolar type and 112 (59%) tumors were classified as the bile duct type. The cholangiolar-type intrahepatic cholangiocarcinoma was more frequently associated with viral hepatitis, whereas all but one intrahepatic cholangiocarcinoma associated with intrahepatic lithiasis were classified as the bile duct type. Biliary intraepithelial neoplasm or intraductal papillary neoplasm of the bile duct could be identified in 50 bile duct-type intrahepatic cholangiocarcinomas (45%), but in only 3 cholangiolar-type intrahepatic cholangiocarcinomas (4%). Cholangiolar-type intrahepatic cholangiocarcinomas frequently expressed N-cadherin, whereas bile duct intrahepatic cholangiocarcinomas were more likely to express S100P, Trefoil factor 1, and anterior gradient 2. KRAS is mutated in 23 of 98 (23%) bile duct-type intrahepatic cholangiocarcinomas and in only 1 of 76 (1%) cholangiolar-type intrahepatic cholangiocarcinomas. Cholangiolar-type intrahepatic cholangiocarcinomas had a higher frequency of IDH1 or 2 mutations than did the bile duct-type intrahepatic cholangiocarcinomas. The molecular features of the bile duct-type intrahepatic cholangiocarcinoma were similar to those of hilar cholangiocarcinoma. Patients with the cholangiolar-type intrahepatic cholangiocarcinoma had higher 5-year survival rates than those of patients with the bile duct-type intrahepatic cholangiocarcinoma. Our results indicated that intrahepatic cholangiocarcinoma was a heterogeneous tumor. Subclassification of intrahepatic cholangiocarcinomas based on cholangiocytic differentiation divides them into two groups with different etiologies, clinical manifestations, and molecular pathogeneses.

Traditional serrated adenoma has two pathways of neoplastic progression that are distinct from the sessile serrated pathway of colorectal carcinogenesis

Traditional serrated adenoma is one type of colorectal serrated neoplasm and a precursor of colorectal cancer. We evaluated the pathologic and molecular features of 60 traditional serrated adenomas with cytologic dysplasia and/or invasive carcinoma. On the basis of morphological features, 16 cases (27%) were categorized as traditional serrated adenoma with serrated dysplasia and 25 cases (42%) as traditional serrated adenoma with conventional adenomatous dysplasia. In addition, 19 cases (31%) showed an overall tubulovillous adenomatous structure but with focal serrated feature. Traditional serrated adenoma with serrated dysplasia had a significantly higher frequency of BRAF mutation than traditional serrated adenoma with conventional adenomatous dysplasia and tubulovillous adenoma with serrated feature (P=0.006), whereas traditional serrated adenoma with conventional adenomatous dysplasia and tubulovillous adenoma with serrated feature had higher frequencies of KRAS mutation than traditional serrated adenoma with serrated dysplasia (P<0.0001). Only traditional serrated adenoma with serrated dysplasia showed sessile serrated adenoma-like lesions at the periphery (n=3) and developed invasive carcinomas when the lesions were <15 mm in size. Abnormal nuclear accumulation of β-catenin was detected in traditional serrated adenoma with conventional adenomatous dysplasia and tubulovillous adenoma with serrated feature but not in traditional serrated adenoma with serrated dysplasia. The frequency of the positive CpG island methylator phenotype was similar among the three dysplastic subtypes, and immunostaining of four mismatch repair proteins in the nucleus was retained in all traditional serrated adenomas and associated invasive malignancies. Traditional serrated adenoma-associated adenocarcinomas (n=28) displayed distinctive morphological features: oval cell nuclei, serrated glands, infiltrating borders, rare occurrences of necrosis and mucinous differentiation. Overexpression of p53 was detected only in high-grade dysplasia and invasive adenocarcinoma. Our findings indicate that traditional serrated adenoma is a heterogeneous neoplasm with two pathways of neoplastic progression, which are distinct from the sessile serrated pathway of colorectal carcinogenesis.

Leiomyosarcoma With Alternative Lengthening of Telomeres Is Associated With Aggressive Histologic Features, Loss of ATRX Expression, and Poor Clinical Outcome

Leiomyosarcoma is an aggressive soft tissue sarcoma with poor patient survival. Recently, it was shown that 53% to 62% of leiomyosarcomas use the alternative lengthening of telomeres (ALT) as their telomere maintenance mechanism. The molecular basis of this mechanism has not been elucidated. Studies of pancreatic neuroendocrine tumor have suggested that the inactivation of either &agr;-thalassemia/mental retardation syndrome X-linked (ATRX) or death domain–associated (DAXX) protein is associated with the ALT phenotype. In this study, we sought to determine the clinicopathologic features of leiomyosarcoma with the ALT phenotype and the possible relationship between this phenotype and ATRX/DAXX expression. Telomerase reverse transcriptase gene (TERT) promoter mutation analysis was also performed. Ninety-two leiomyosarcomas derived from the uterus, retroperitoneum/intra-abdomen, and various other sites were analyzed. Telomere-specific fluorescence in situ hybridization revealed that 59% (51/86) of leiomyosarcomas had the ALT phenotype. Loss of ATRX expression was observed in 33% of the tumors (30/92), and all but 2 ATRX-deficient tumors were ALT positive. Both the ALT phenotype and loss of ATRX expression were associated with epithelioid/pleomorphic cell morphology, tumor necrosis, and poor differentiation. None of the 92 cases lost DAXX expression. No TERT promoter mutation was detected (n=39). For survival analysis, poor differentiation, high FNCLCC grade, tumor size, and ALT phenotype were correlated with poor overall survival in univariate analysis. Tumor size and ALT phenotype remained independent prognostic factors in multivariate analysis. We concluded that the ALT phenotype in the leiomyosarcoma is associated with aggressive histologic features, loss of ATRX expression, and poor clinical outcome.

TERT promoter mutation is uncommon in acral lentiginous melanoma.

Melanoma is a heterogeneous group of diseases with distinct sets of genetic changes. Recurrent and mutually exclusive C>T or CC>TT transition mutations were identified in the promoter region of the reverse transcriptase catalytic subunit of the telomerase gene (TERT) in melanoma recently, and it was suggested that they enhanced the expression of TERT gene and played important roles in the melanoma pathogenesis. These mono or di‐nucleotide transitions were ultraviolet (UV)‐signature mutations.

The presence of clusters of plasmacytoid dendritic cells is a helpful feature for differentiating lupus panniculitis from subcutaneous panniculitis-like T-cell lymphoma.

Both lupus panniculitis (LP) and subcutaneous panniculitis‐like T‐cell lymphoma (SPTCL) are characterized by subcutaneous lobular lymphocytic infiltrates, and they are sometimes difficult to differentiate. Recently, plasmacytoid dendritic cells (PDCs) were found to be present in various types of cutaneous lupus erythematosus lesions, including LP, and are supposed to play important pathogenetic roles. The aim of this study was to investigate whether PDCs are differentially present in these two diseases and can be utilized to differentiate them. Conventional histopathological features were also compared.

GNAS Is frequently mutated in a specific subgroup of intraductal papillary neoplasms of the bile duct.

Intraductal papillary neoplasms of the bile duct (IPN-Bs) share clinicopathologic features with intraductal papillary mucinous neoplasms (IPMNs) of the pancreas. Approximately two thirds of IPMNs have activating point mutations of GNAS at codon 201. The role of GNAS mutation is unclear in IPN-B. In this study, we evaluated 41 patients diagnosed with IPN-B for clinicopathologic characteristics and follow-up information. Mutation analyses of GNAS and KRAS were performed. Twenty-three cases (56.1%) of IPN-B were categorized as the intestinal subtype, and 18 (43.9%) were considered the gastric/pancreatobiliary subtype. IPN-Bs showing intestinal differentiation demonstrated high immunohistochemical expressions of CK20, CDX2, and MUC2, as well as a significant association with macroscopic and microscopic mucin hypersecretions and villous architecture. GNAS and KRAS mutations were detected in 29% and 32% of IPN-Bs, respectively. All IPN-Bs with GNAS mutation showed intestinal differentiation. GNAS-mutated IPN-B was highly significantly associated with certain pathologic characteristics, including macroscopic and microscopic mucin hypersecretion and villous architecture. IPN-B with GNAS mutation tended to more frequently harbor KRAS mutation than those without GNAS mutation. IPN-Bs with intestinal differentiation, villous architecture, and mucin hypersecretion constitute a distinct subgroup of IPN-B, which frequently has GNAS mutation. This subtype shares common genetic alterations with IPMN of the pancreas.

S100P immunostaining identifies a subset of peripheral-type intrahepatic cholangiocarcinomas with morphological and molecular features similar to those of perihilar and extrahepatic cholangiocarcinomas.

Tsai J‐H, Huang W‐C, Kuo K‐T, Yuan R‐H, Chen Y‐L & Jeng Y‐M 
(2012) Histopathology
S100P immunostaining identifies a subset of peripheral‐type intrahepatic cholangiocarcinomas with morphological and molecular features similar to those of perihilar and extrahepatic cholangiocarcinomas

Alternative lengthening of telomeres and loss of ATRX are frequent events in pleomorphic and dedifferentiated liposarcomas

Telomerase activation and alternative lengthening of telomeres are two major mechanisms of telomere length maintenance. Soft tissue sarcomas appear to use the alternative lengthening of telomeres more frequently. Loss of α-thalassemia/mental retardation syndrome X-linked (ATRX) or death domain-associated protein 6 (DAXX) expression has been implicated in the pathogenesis of alternative telomere lengthening in pancreatic endocrine neoplasm and glioma. The mechanism leading to the alternative lengthening of telomeres in liposarcoma remains unknown. Whereas alternative telomere lengthening was determined to be an indicator of poor prognosis in liposarcomas as a whole, its prognostic power has not been verified in any subtype of liposarcoma. In this study, we characterized the status of alternative telomere lengthening and expression of ATRX and DAXX in 111 liposarcomas (28 well-differentiated, 52 dedifferentiated, 20 myxoid or round cell, and 11 pleomorphic liposarcomas) by telomere fluorescence in situ hybridization and immunohistochemistry, respectively. Alternative lengthening of telomere was observed in 0% (0/16) of well-differentiated, 30% (14/46) of dedifferentiated, 5% (1/19) of myxoid or round cell, and 80% (8/10) of pleomorphic liposarcomas. Eighteen (16%) and one (1%) tumors were negative for ATRX and DAXX immunostaining, respectively. Remarkably, all cases with loss of either ATRX or DAXX expression had alternative lengthening of telomeres, and 83% (19/23) of tumors that had alternative lengthening of telomeres showed loss of either protein. The correlation between loss of either ATRX or DAXX and alternative telomere lengthening was 100% in dedifferentiated liposarcoma. The presence of alternative telomere lengthening in dedifferentiated liposarcoma suggested poor overall survival (hazard ratio=1.954, P=0.077) and was the most significant indicator of short progression-free survival (hazard ratio=3.119, P=0.003). In conclusion, we found that ATRX loss was the most likely mechanism of alternative telomere lengthening in liposarcoma and alternative telomere lengthening was a prognostic factor of poor outcome in dedifferentiated liposarcoma.

Comprehensive screening of alternative lengthening of telomeres phenotype and loss of ATRX expression in sarcomas.

According to cytogenetic aberrations, sarcomas can be categorized as complex or simple karyotype tumors. Alternative lengthening of telomeres is a telomere-maintenance mechanism common in sarcomas. Recently, this mechanism was found to be associated with loss of either α-thalassemia/mental retardation syndrome X-linked (ATRX) or death domain-associated (DAXX) protein. We previously reported that alternative lengthening of telomeres and loss of ATRX expression were common in leiomyosarcoma, angiosarcoma, pleomorphic liposarcoma, and dedifferentiated liposarcoma. In the present study, we screened an additional 245 sarcomas of other types to determine the prevalence of alternative lengthening of telomeres, loss of ATRX/DAXX expression, and their relationship. Undifferentiated pleomorphic sarcomas were frequently alternative lengthening of telomeres positive (65%) and loss of ATRX was seen in approximately half of the alternative lengthening of telomeres-positive tumors. Nineteen of 25 myxofibrosarcomas were alternative lengthening of telomeres-positive, but only one was ATRX deficient. Three of 15 radiation-associated sarcomas were alternative lengthening of telomeres positive, but none of them was ATRX deficient. Alternative lengthening of telomeres and/or loss of ATRX were uncommon in malignant peripheral nerve sheath tumors, gastrointestinal stromal tumors, and embryonal rhabdomyosarcomas. By contrast, none of the 71 gene fusion-associated sarcomas was ATRX deficient or alternative lengthening of telomeres positive. All tumors exhibited preserved DAXX expression. Combining our previous studies and this study, a total of 384 sarcomas with complex karyotypes were examined, 83 of which were ATRX deficient (22%). By telomere-specific fluorescence in situ hybridization, 45% (138/308) were alternative lengthening of telomeres positive, 55% (76/138) of which were ATRX deficient. Loss of ATRX was highly associated with alternative lengthening of telomeres (P<0.001). We conclude that alternative lengthening of telomeres is a frequent telomere-maintenance mechanism in cytogenetically complex sarcomas. Loss of ATRX is highly associated with this feature.

Alternative lengthening of telomeres phenotype in malignant vascular tumors is highly associated with loss of ATRX expression and is frequently observed in hepatic angiosarcomas

Alternative lengthening of telomeres (ALT) is a mechanism using homologous recombination to maintain telomere length and sustain limitless replicability of cancer cells. Recently, ALT has been found to be associated with inactivation of either α-thalassemia/mental retardation syndrome X-linked (ATRX) or death domain-associated (DAXX) protein. In this study, 119 tumors (88 angiosarcomas, 11 epithelioid hemangioendotheliomas, and 20 Kaposi sarcomas) were analyzed to determine the ALT status, its relationship to loss of ATRX/DAXX expression, and the clinicopathological features. In addition, the mutation status in the telomerase reverse transcriptase gene (TERT) promoter was also studied. Loss of ATRX expression was observed in 21% (16/77) of the primary angiosarcomas and 9% (1/11) of epithelioid hemangioendotheliomas. DAXX expression was intact in all but 2 ATRX-deficient angiosarcomas. Telomere-specific fluorescence in situ hybridization assay showed 28% (17/61) of the primary angiosarcomas were ALT positive. Remarkably, ALT was highly associated with loss of ATRX expression: all but 2 ALT-positive angiosarcomas were ATRX deficient. Notably, hepatic angiosarcomas were frequently ATRX deficient (8/13) and/or ALT positive (8/12). None of the secondary angiosarcomas were ATRX/DAXX deficient or ALT positive. The only ATRX-deficient epithelioid hemangioendothelioma was positive for ALT. Forty-seven angiosarcomas were tested for TERT promoter mutation. Despite the fact that angiosarcoma occurs most commonly in sun-damaged skin, mutation was detected in only 1 radiation-associated angiosarcoma (2%). We conclude that ALT is an important telomere maintenance mechanism in primary angiosarcomas. This feature is highly associated with loss of ATRX expression and is frequently observed in hepatic angiosarcomas.