Intrahepatic cholangiocarcinoma resembling a thyroid follicular neoplasm

Defining molecular signatures of the solid/pseudopapillary and pseudoglandular patterns in so-called "solid-tubulocystic intrahepatic cholangiocarcinoma vs. NIPBL::NACC1 fusion hepatic carcinoma"

Solid-tubulocystic variant of intrahepatic cholangiocarcinoma (ST-iCCA) is newly described entity characterized by two distinct histologic growth patterns: (1) solid sheets of tumor cells with focal necrosis giving pseudopapillary appearance and (2) tubular or pseudoglandular structures containing pink, colloid-like material. Tumor cells are inhibin-positive and harbor NIPBL::NACC1 fusion gene. To date, only 28 cases of ST-iCCA have been documented. While prior molecular studies provided insights into ST-iCCA, genetic profiles of individual histologic components have not been explored. This study presents first transcriptomic analysis comparing the solid/pseudopapillary and pseudoglandular components of ST-iCCA. Two cases of histologically confirmed ST-iCCA were identified for RNA sequencing which was performed on solid/pseudopapillary component, pseudoglandular component, and normal tissue. Analysis revealed distinct gene expression profiles for each pattern. Solid/pseudopapillary component uniquely overexpressed DMRTA1, NEXMIF, PRDM6, SORCS3, and NALF, while pseudoglandular component exhibited unique overexpression of HRG, ITIH3, TAT, APOA2, CP, ALDOB, CPS1, F2, KHG1, SERPINC1, HPX, C9, ADGRF1, MUC21, SAA2, SPRR2A, SAA1, FGL1, CFHR1, and LBP. These findings establish unique gene signatures for these variants of ST-iCCA, providing potential biomarkers for differential diagnosis, prognosis and targeted therapy. The distinct genetic profiles may also uncover novel therapeutic targets to address the aggressive nature of ST-iCCA.

Case report: Rare observation of thyroid-like cholangiocarcinoma

Intrahepatic cholangiocarcinoma is a highly malignant tumor with a poor prognosis. Radical surgical resection remains the "gold standard" for improving patient outcomes; however, only a minority of patients qualify for this approach. Intrahepatic cholangiocarcinoma is primarily classified into two major histologic types: small and large ductal cholangiocarcinomas. Nevertheless, rare subtypes with unique diagnostic and prognostic characteristics are increasingly reported. These subtypes often exhibit features such as slow growth, a histologic architecture resembling thyroid tissue, or ductal ectasia, and are associated with a more favorable prognosis. We present the case of a 61-year-old patient with a solitary liver mass initially identified as a hemangioma through imaging studies. Histopathologic examination of the postoperative specimen revealed a thyroid-like structural pattern. Immunohistochemical analysis showed positive staining for CK7 and CK19, confirming the diagnosis of intrahepatic cholangiocarcinoma with a thyroid-like structure. The tumor was completely resected with clear margins, and no evidence of metastasis was found. Consequently, the patient was managed without adjuvant chemotherapy. At 14 months of follow-up, there were no signs of recurrence or metastasis. This clinical case underscores the importance of recognizing novel subtypes of cholangiocarcinoma and exercising vigilance in the management of patients with presumed benign hepatic lesions.

NIPBL::NACC1 Fusion Hepatic Carcinoma

Several reports describing a rare primary liver tumor with histologic features reminiscent of follicular thyroid neoplasms have been published under a variety of descriptive terms including thyroid-like, solid tubulocystic, and cholangioblastic cholangiocarcinoma. Although these tumors are considered to represent histologic variants, they lack classic features of cholangiocarcinoma and have unique characteristics, namely immunoreactivity for inhibin and NIPBL::NACC1 fusions. The purpose of this study is to present clinicopathologic and molecular data for a large series of these tumors to better understand their pathogenesis. We identified 11 hepatic tumors with these features. Immunohistochemical and NACC1 and NIPBL fluorescence in situ hybridization assays were performed on all cases. Four cases had available material for whole-genome sequencing (WGS) analysis. Most patients were adult women (mean age: 42 y) who presented with abdominal pain and large hepatic masses (mean size: 14 cm). Ten patients had no known liver disease. Of the patients with follow-up information, 3/9 (33%) pursued aggressive behavior. All tumors were composed of bland cuboidal cells with follicular and solid/trabecular growth patterns in various combinations, were immunoreactive for inhibin, showed albumin mRNA by in situ hybridization, and harbored the NIPBL::NACC1 fusion by fluorescence in situ hybridization. WGS corroborated the presence of the fusion in all 4 tested cases, high tumor mutational burden in 2 cases, and over 30 structural variants per case in 3 sequenced tumors. The cases lacked mutations typical of conventional intrahepatic cholangiocarcinoma. In this report, we describe the largest series of primary inhibin-positive hepatic neoplasms harboring a NIPBL::NACC1 fusion and the first WGS analysis of these tumors. We propose to name this neoplasm NIPBL:NACC1 fusion hepatic carcinoma.

Inhibin-Positive "Cholangioblastic" Variant of Intrahepatic Cholangiocarcinoma: Report of 3 New Patients With Review of the Literature

Cholangiocarcinoma is the second most common primary liver malignant neoplasm. It usually affects older individuals in their seventh decade of life with no gender predilection. Recently, a distinct subtype of cholangiocarcinoma has emerged with 2 proposed names: "cholangioblastic" and "solid tubulocystic." This variant predominantly occurs in younger women who lack the common risk factors for patients diagnosed with cholangiocarcinomas, such as older age and chronic liver disease or cirrhosis. We describe 3 new patients with a cholangioblastic variant of intrahepatic cholangiocarcinoma. At the time of diagnosis, the patients were aged 19-, 46-, and 28-year-old; 2 females and 1 male (the 46-year-old). None of our patients had a history of chronic liver disease or known predisposing factors for liver tumors. Tumor size ranged from 2.3 to 23 cm in greatest dimension. Histological examination of these tumors demonstrated reproducible morphology characterized by trabecular, nested, and multicystic patterns with micro and macro follicles filled with eosinophilic material. The immunohistochemical profile showed that the tumor cells were positive for keratin 7, inhibin, synaptophysin, and albumin in situ hybridization, while negative for HepPar1, arginase, and INSM1. All tumors lacked conventional intrahepatic cholangiocarcinoma/adenocarcinoma morphology. We also review the literature and emphasize that neuroendocrine tumors should be recognized as a major diagnostic pitfall of this variant.

Solid-Tubulocystic carcinoma: A new variant of intrahepatic cholangiocarcinoma

A new variant of intrahepatic cholangiocarcinoma (iCCA) has been recognized in recent years presenting predominantly as a large hepatic mass in young woman with the characteristic expression of inhibin by immunohistochemistry. This variant iCCA was originally termed as cholangioblastic variant of iCCA, and subsequently proposed to be renamed as inhibin-positive hepatic carcinoma or solid-tubulocystic variant of iCCA to better reflect its immunohistochemical profile or morphologic spectrum. The tumor histologically is composed of small to medium sized cells with scant to moderate amount of eosinophilic cytoplasm heterogeneously organized in solid, tubular, and cystic growth patterns. The tumor cells are positive for biliary markers, inhibin and albumin, and have a novel recurrent gene fusion, NIPBL::NACC1. Awareness of this new iCCA variant and its clinicopathologic features will aid in the diagnostic work-up and avoid confusion with other primary and metastatic hepatic neoplasms.

Solid-Tubulocystic Variant of Intrahepatic Cholangiocarcinoma: Report of a Pediatric Case With Molecular Characterization

We present a case of solid-tubulocystic variant of intrahepatic cholangiocarcinoma (also called cholangioblastic variant of intrahepatic cholangiocarcinoma) in a 15-year-old girl, the youngest patient reported to date. The tumor was located in the left lobe of the liver, predominantly solid with cystic areas, and measured 16 cm in greatest dimension. Microscopic examination showed 2 major histologic patterns: a mixed pattern with solid, tubulocystic, macrocystic, trabecular, and nested growth, diffuse cytokeratin 7/19 and weak neuroendocrine immunoreactivity, and low Ki-67 index; and a more compact, macrotrabecular/gyriform pattern with focal CK7/19, stronger neuroendocrine reactivity, and higher Ki-67 index. Inhibin immunoreactivity was diffuse throughout both patterns. Treatment included tumor resection with negative margins and 8 cycles of capecitabine chemotherapy; the patient is alive with no evidence of tumor 2.5 years after resection. Although molecular characterization of the tumor at the time of resection was unrevealing, a recent study has identified a novel NIPBL-NACC1 fusion transcript in this tumor type, which we have confirmed in this case. This case expands the reported age range of this rare tumor type and confirms a recently-reported diagnostic genomic alteration. Awareness of this rare entity affecting pediatric patients is crucial to avoid confusion with similar-appearing neoplasms.

Hepatic carcinoma expressing inhibin: case report of a proposed novel entity and review of the literature

Hepatic carcinoma expressing inhibin is a recently described neoplasm with varied architecture, including trabecular, pseudoglandular, follicular/microcystic, organoid, solid and tubular patterns of growth. We report a case of hepatic carcinoma expressing inhibin that occurred in a 47-year-old woman presenting with epigastric and back pain. The tumor was located in the left hepatic lobe and measured 12 cm in diameter. On immunohistochemical stains, the neoplastic cells were positive for inhibin, as well as cytokeratins 7, 8/18 and 19. There was mild focal expression of synaptophysin, and lack of expression of hepatocytic markers. The histogenesis of hepatic carcinoma expressing inhibin is presently uncertain. From a practical point of view, this neoplasm can potentially cause diagnostic pitfalls by simulating other primary or metastatic tumors, such as hepatocellular carcinoma, cholangiocarcinoma, neuroendocrine tumors, and follicular carcinoma of thyroid gland. Performing inhibin immunostain could assist in the differential diagnosis of liver tumors with unusual histologic features.

Gene Fusions in Gastrointestinal Tract cancers

Fusion genes have been identified a wide array of human neoplasms including hematologic and solid tumors, including gastrointestinal tract neoplasia. A fusion gene is the product of parts of two genes which are joined together following a deletion, translocation or chromosomal inversion. Together with single nucleotide variants, insertions, deletions, and amplification, fusion genes represent one of the key genomic mechanisms for tumor development. Detecting fusions in the clinic is accomplished by a variety of techniques including break-apart fluorescence in situ hybridization (FISH), reverse transcription-polymerase chain reaction (RT-PCR), and next-generation sequencing (NGS). Some recurrent gene fusions have been successfully targeted by small molecule or monoclonal antibody therapies (i.e. targeted therapies), while others are used for as biomarkers for diagnostic and prognostic purposes. The purpose of this review article is to discuss the clinical utility of detection of gene fusions in carcinomas and neoplasms arising primarily in the digestive system. This article is protected by copyright. All rights reserved.

Inhibin-positive hepatic carcinoma: proposal for a solid-tubulocystic variant of intrahepatic cholangiocarcinoma

Inhibin-positive hepatic carcinoma is a rare primary liver neoplasm that resembles sex cord-stromal tumor and thyroid follicular tumors. The term "cholangioblastic variant of intrahepatic cholangiocarcinoma" has been proposed. This study describes the clinicopathologic, immunophenotypic, and molecular features of a small series (n = 6) of this rare tumor. Albumin in situ hybridization (ISH) and capture-based next-generation sequencing (NGS) were also performed. All tumors occurred in young women (mean age 32.5 years, range 19-44 years) as a solitary large mass (mean 15.8 cm, range 6.9-23.5 cm). All tumors showed a highly distinctive morphology with sheets and large nests of tumor cells alternating with tubular and cystic areas imparting a sex cord-like or thyroid follicle-like morphology. Cytologic atypia was mild, and mitotic activity was low. All cases were positive for inhibin, as well as pancytokeratin, CK7, CK19, and albumin ISH. Synaptophysin and chromogranin showed focal or patchy staining, whereas INSM1 was negative. Markers for hepatocellular differentiation, thyroid origin, and sex cord-stromal tumor were negative. There were no recurrent genomic changes based on capture-based NGS of ∼500 cancer genes. Recurrence and/or metastasis was seen in three (50%) cases (follow-up time range for all cases: 5 months to 2 years). In conclusion, this series describes the distinctive morphology, immunophenotypic features, and diffuse albumin staining in six cases of a rare inhibin-positive primary liver carcinoma that runs an aggressive course similar to intrahepatic cholangiocarcinoma. Genomic changes typical of cholangiocarcinoma or hepatocellular carcinoma were not identified, and there were no recurrent genetic abnormalities. We propose the term "solid-tubulocystic variant of intrahepatic cholangiocarcinoma" to reflect the spectrum of morphologic patterns observed in this tumor.

Thyroid-Like Cholangiocarcinoma: Histopathological, Immunohistochemical, In-Situ Hybridization and Molecular Studies on an Uncommon Emerging Entity

Thyroid-like cholangiocarcinoma is a very uncommon variant of peripheral-type cholangiocarcinoma. To date, only 4 prior cases have been reported. The molecular features of this tumor have not been described. We report a case of a 60-year-old woman with a tumor that evolved over a period of 10 years. A left hepatectomy specimen showed an 11 cm tumor that on histology exhibited areas reminiscent of a thyroid tumor with follicular and insular features which were positive on immunohistochemistry for cytokeratin 7 and in-situ hybridization for albumin. A detailed molecular analysis failed to show mutations common to cholangiocarcinomas but revealed frameshift mutations in 2 chromatin-remodeling genes, CREBBP and KMNT2A. This case confirms that thyroid-like cholangiocarcinoma is a histologic variant of this tumor that is associated with relatively low growth. As most cholangiocarcinomas, it is diffusely positive for cytokeratin 7 and albumin by in-situ hybridization. Given its rarity, the molecular alterations in this specific histologic subtype remain to be fully elucidated.

Rare Histological Variants of Liver Cancer and Their Management: A Single-Institution Experience

Primary liver malignancies, including hepatocellular carcinoma (HCC) and cholangiocarcinoma, are a major cause of cancer-related morbidity and mortality worldwide. There are several histologically and biologically distinct subtypes of liver cancer that have previously been reported. However, literature regarding the nonsurgical management of these patients upon disease recurrence remains limited. These variants include combined HCC-cholangiocarcinoma (cHCC-CC), Epstein–Barr virus- (EBV-) associated carcinoma, undifferentiated carcinoma, and clear cell or thyroid-like variants of HCC. Here, we aim to highlight the pathologic features, clinical course, and outcomes of five patients with these unusual hepatic tumors and explain the rationale behind the choice of their systemic therapies upon disease recurrence. All patients underwent surgical resection as the standard of care for localized disease, and upon relapse, they were treated with either chemotherapy, targeted therapy, immunotherapy, or active surveillance based on the clinical context and tumor histology. These rare variants are important to recognize as they have prognostic and therapeutic implications, and there are currently insufficient data in the literature to guide further therapy.

Pathologic Doppelgänger: Thyroid-like intrahepatic cholangiocarcinoma with synchronous primary thyroid carcinoma in a young woman

Intrahepatic cholangiocarcinoma (ICC) accounts for 8-10% of all malignant liver tumors. Preponderance for elderly males and occurrence of varied morphological patterns in ICC is well known. Recent reports have described a newly recognized variant of thyroid-like cholangiocarcinoma. Herein, we present a hitherto unreported synchronous occurrence of an intrahepatic thyroid-like cholangiocarcinoma and a separate thyroid carcinoma in a 23-year-old post-partum woman. Both tumors displayed striking resemblance to follicular variant of papillary thyroid carcinoma (FVPTC) however exhibited disparate immunohistochemical profiles: the intrahepatic tumor was positive for CK7 and CK19, and negative for TTF-1, PAX-8 and thyroglobulin whereas, the thyroid tumor was positive for TTF-1, thyroglobulin and PAX-8. Young age, female proclivity, large mass at presentation and unique histology in thyroid-like ICC hint towards a distinctive subset of ICC. Awareness and recognition of this rare entity is essential, not only for accurate diagnosis, but also for gathering information on its biology and clinical behavior. Synchronous occurrence with a FVPTC is a challenging scenario that can simulate metastatic disease and mislead subsequent patient management. Whether morphologic similarity points to an underlying linkage between the two different tumors needs exploration.

Thyroid-Like Intrahepatic Cholangiocarcinoma: Report of a Case and Review of the Literature

Intrahepatic cholangiocarcinoma is a relatively uncommon malignant neoplasm. We recently encountered an unusual case of intrahepatic cholangiocarcinoma that histologically resembled a thyroid carcinoma. A thorough review of the English literature revealed only 2 similar cases that have been previously reported. Immunohistochemical studies are imperative to confirm the diagnosis of cholangiocarcinoma and to exclude the possibility of metastatic thyroid carcinoma and other malignancies with thyroid-like features.

Primary Hepatic Neuroendocrine Tumor with Unusual Thyroid Follicular-Like Morphologic Characteristics

We describe a primary hepatic neuroendocrine tumor of a 57-year-old Thai woman who presented in 2004 with a suspicious mass in the left hepatic lobe. She underwent left hepatectomy for the 10.5-cm mass, called intermediate grade neuroendocrine carcinoma of unknown origin, likely metastatic. The tumor recurred in 2007, then called recurrent primary hepatic neuroendocrine tumor (PHNET), and the patient underwent liver transplant. Because of similarity between the neuroendocrine tumor and a thyroid tumor-specifically, follicular-like characteristics-immunohistochemical stains for thyroglobulin, TTF1, and calcitonin were performed. However, all were negative. All imaging studies revealed no evidence of a primary lesion other than the liver mass. In 2008, the patient's liver transplant failed because of ischemic cholangiopathy, and she underwent a second liver transplant. Seven years later, in 2015, she presented with metastatic neuroendocrine tumor of intermediate grade to the lung, consistent with metastatic PHNET. She underwent left upper-lobe wedge resection to remove the tumor. The patient is alive with no evidence of disease at 13 years after initial diagnosis. This rare variant of PHNET had thyroid-like morphologic characteristics but there is no evidence of primary thyroid tumor or thyroid markers in the primary and recurrent hepatic tumors and lung metastasis.

Thyroid-like follicular carcinoma of the kidney: one case report and review of the literature

OBJECTIVES

Thyroid-like follicular carcinoma of the kidney continues to confound the practicing pathologist with its close resemblance to the follicular variant of thyroid carcinoma, as well as other benign and malignant entities. Our goal is to expand the knowledge of this rare renal cell carcinoma subtype, which is morphologically similar to follicular carcinoma of the thyroid but lacks expression of characteristic thyroid immunohistochemical markers such as TTF-1 and thyroglobulin.

METHODS

We evaluated the gross, histologic, immunohistochemical, and fluorescence in situ hybridization (FISH) studies of a new case and performed a comprehensive review of the literature.

RESULTS

The lesion was spongy and well-circumscribed. Microscopically it showed variably sized follicular structures, filled with abundant, deeply eosinophilic, colloid-like material. At the periphery, it displayed areas resembling metanephric adenoma and early stages of nephrogenesis. The tumor cells strongly expressed CK7, PAX-8, PAX-2, vimentin, EMA, and CK19 immunostains. Other markers, such as CD10, RCC, HBME-1, thyroglobulin, and TTF-1, were not immunoreactive. The tumor was negative for trisomy of both 7 and 17 and showed borderline monosomies (losses) of both chromosomes in FISH studies.

CONCLUSIONS

Five years of preoperative observation and lack of recurrence bring further insight into the slow progressive nature of this neoplasm and support a low malignant potential. Proper identification is important to secure adequate treatment and follow-up.

Thyroid-like follicular carcinoma of the kidney in a young patient with history of pediatric acute lymphoblastic leukemia

Thyroid-like follicular carcinoma of the kidney (TLFCK) is a rare histological variant of renal cell carcinoma not currently included in the World Health Organization classification of renal tumors. Only 24 previous cases of TLFCK have been reported to date. We report a case of TLFCK in a 19-year-old woman with history of pediatric acute lymphoblastic leukemia. This patient is the youngest with TLFCK to be reported to date and the first with history of lymphoblastic leukemia. The development of TLFCK in a young patient with history of lymphoblastic leukemia is interesting and suggests that genes involved in leukemogenesis may also be important for TLFCK pathogenesis. Recognition of TLFCK is important to distinguish it from other conditions that show thyroid-like features, as a misdiagnosis can result in adverse patient care.

Intraductal tubular neoplasms of the bile ducts

Although most tumors of the bile ducts are predominantly invasive, some have an exophytic pattern within the bile ducts; these intraductal papillary neoplasms usually have well-formed papillae at the microscopic level. In this study, however, we describe a novel type of intraductal neoplasm of the bile ducts with a predominantly tubular growth pattern and other distinctive features. Ten cases of biliary intraductal neoplasms with a predominantly tubular architecture were identified in the files of the Pathology Department at Memorial Sloan-Kettering Cancer Center from 1983 to 2006. For each of these cases we studied the clinical presentation, histologic and immunohistochemical features (9 cases only), and the clinical follow-up of the patients. Three male and 7 female patients (38 to 78 y) presented with obstructive jaundice or abdominal pain. Eight of the patients underwent a partial hepatectomy; 2 underwent a laparoscopic bile duct excision, followed by a pancreatoduodenectomy in one of them. The tumors range in size from 0.6 to 8.0 cm. The intraductal portions of the tumors (8 intrahepatic, 1 extrahepatic hilar, 1 common bile duct) were densely cellular and composed of back-to-back tubular glands and solid sheets with minimal papillary architecture. The cells were cuboidal to columnar with mild to moderate cytologic atypia. Foci of necrosis were present in the intraductal component in 6 cases. An extraductal invasive carcinoma component was present in 7 cases, composing <25% of the tumor in 4 cases, and >75% in 1 case. It was observed by immunohistochemical analysis that the tumor cells expressed CK19, CA19-9, MUC1, and MUC6 in most cases and that SMAD4 expression was retained. MUC2, MUC5AC, HepPar1, synaptophysin, chromogranin, p53, and CA125 were negative in all cases and most were negative for CEA-M and B72.3. Four patients were free of tumor recurrence after 7 to 85 months (average, 27 mo). Four patients with an invasive carcinoma component suffered metastases, 1 after local intraductal recurrence. However, the occurrence of metastasis in 3 of these patients was quite late (average, 52 mo). Intraductal tubular neoplasm of the bile ducts is a biliary intraductal neoplasm with a distinctive histologic pattern resembling the recently described intraductal tubulopapillary neoplasm of the pancreas. Immunohistochemical features are similar to those of other pancreatobiliary-type carcinomas. However, this tumor may be hard to recognize as intraductal because of its complex architecture. When the tumor is entirely intraductal, the outcome appears to be favorable, but metastases can occur when invasive carcinoma is present, even after many years.

Thyroid-like follicular carcinoma of the kidney: report of two cases with detailed immunohistochemical profile and literature review

Thyroid-like follicular carcinoma of the kidney (TLFC) is an unusual histological variant of renal cell carcinoma not included in the current WHO classification of renal tumors. Its morphological features resemble a large spectrum of benign and malignant renal and extra-renal conditions which should be ruled out in the diagnostic process. Because TLFC outcome is different from the other variants of renal cell carcinoma, the exploration for disease-specific markers is mandatory. The aim of the present paper is to illustrate the histological characteristics and immunohistochemical profile of two new cases along with a brief review of the literature.

Thyroid-like metastases to the scalp from a papillary renal cell carcinoma: a case report

The skin can host metastatic tumors originating from different organs. We report a case of metastatic renal cell carcinoma to the scalp in a 73-year-old man with features very similar to those of thyroid papillary carcinoma. The histogenesis in relation to its structure is discussed.

Intraductal tubulopapillary neoplasm of the bile duct: potential origin from peribiliary cysts

We report two patients with unique biliary tumors histologically similar to pancreatic intraductal tubulopapillary neoplasm (ITPN). One patient underwent right hepatectomy for a partly cystic mass in the hepatic hilum. The other patient had liver transplantation for cryptogenic cirrhosis and multiple hilar cysts detected in the explanted liver, some obliterated by papillary nodules. Histologically both tumors consisted of intracystic non-invasive and well differentiated adenocarcinoma with a papillary and tubular architecture. Associated cysts were peribiliary cysts partly lined by carcinoma cells that were continuous with the intracystic papillotubular masses. Both tumors shared the same immunophenotype: K7(+)/K20(-)/MUC1(+)/MUC2(-)/MUC5AC(-)/MUC6(+). Genetic analysis of KRAS and BRAF revealed wild type genotypes. These pathological and genetic features are similar to those of pancreatic ITPNs. This report suggested that ITPNs may rarely develop in the bile duct seemingly in association with peribiliary cysts.