A novel case of rhabdoid colon carcinoma associated with a positive CpG island methylator phenotype and BRAF mutation

SMARCB1/INI1-Deficient Poorly Differentiated Carcinoma of the Colon With Rhabdoid Features-A Rare Tumor With Serrated Phenotype: Case Report and Review of Literature

Poorly differentiated colonic carcinoma with rhabdoid features is a rarely described entity. Our knowledge regarding the molecular phenotype of the tumor is evolving. We herein report a similar tumor with rhabdoid differentiation identified in the splenic flexure, which on histological examination showed a poorly differentiated phenotype with epithelioid to spindled morphology, tumor giant cells, and rhabdoid differentiation. The tumor was mismatch repair-proficient, deficient of INI1/SMARCB1, KRAS mutated (A146×), BRAFV600E mutated (c.1799T > A), and NRAS wild-type, indicating serrated differentiation in the tumor. The patient died after 3.5 months post-surgery. INI1-deficient poorly differentiated carcinoma of the colon is a rare, aggressive colonic malignancy showing a serrated phenotype. Routine identification and subtyping are important keeping in mind the distinct tumor phenotype, resistance to conventional chemotherapy, and dismal prognosis.

Cilia and Cancer: From Molecular Genetics to Therapeutic Strategies

Cilia are microtubule-based organelles that project from the cell surface with motility or sensory functions. Primary cilia work as antennae to sense and transduce extracellular signals. Cilia critically control proliferation by mediating cell-extrinsic signals and by regulating cell cycle entry. Recent studies have shown that primary cilia and their associated proteins also function in autophagy and genome stability, which are important players in oncogenesis. Abnormal functions of primary cilia may contribute to oncogenesis. Indeed, defective cilia can either promote or suppress cancers, depending on the cancer-initiating mutation, and the presence or absence of primary cilia is associated with specific cancer types. Together, these findings suggest that primary cilia play important, but distinct roles in different cancer types, opening up a completely new avenue of research to understand the biology and treatment of cancers. In this review, we discuss the roles of primary cilia in promoting or inhibiting oncogenesis based on the known or predicted functions of cilia and cilia-associated proteins in several key processes and related clinical implications.

Pleomorphic (giant cell) carcinoma revisited: A historical perspective and conceptual reappraisal

The term pleomorphic "giant cell" carcinoma was coined by Sommers and Meissner in 1954 for a pancreatic carcinoma variant showing a "sarcoma-like transformation" and characterized by an admixture of undifferentiated cells with striking variation in size and shape. Based on the predominant cell type, four patterns were recognized: spindle cell (sarcomatoid), pleomorphic "giant cell", osteoclastic giant cell-rich, and anaplastic round cell. These four basic patterns frequently coexisted within same tumor, albeit to a significantly variable extent. Follow-up series further characterized the entity, expanded its topographic distribution to include almost all organ systems, and illustrated its morphological and phenotypic homology among different organs. Although resemblance of the neoplastic cells to rhabdomyoblasts was already pointed out by Stout in 1958, the term "rhabdoid" (introduced in 1978 for specific kidney tumors) was not used for carcinomas until 1993. Review of the old and recent literature indicates pleomorphic "giant cell" carcinoma is not an entity but a morphological pattern in the spectrum of undifferentiated (anaplastic) and sarcomatoid carcinoma that can originate in any organ, either in a pure form or as a dedifferentiated carcinoma component. These tumors fall into two major categories: a monomorphic (variable admixture of small or larger "gemistocyte-like" rhabdoid cells and epithelioid cells) and a pleomorphic (bizarre large polygonal, spindled, or multinucleated malignant cells) subtype. The few available genetic studies suggest close association of the monomorphic type with SWI/SNF pathway defects, while bizarre-looking pleomorphic tumors usually harbor complex and heterogeneous genetic alterations. Most tumors dominated by the pleomorphic "giant cell" pattern are extremely aggressive, resulting in death, soon after diagnosis, irrespective of treatment modalities. This review gives an historical account on the evolution of the pleomorphic "giant cell" carcinoma concept with special reference to their relationship to SWI/SNF complex alterations.

INI1-negative colorectal undifferentiated carcinoma with rhabdoid features and postoperative rapidly growing liver metastases: a case report and review of the literature

BACKGROUND

Malignant tumors with rhabdoid features are extremely rare. They can occur in various organs, including the gastrointestinal tract, with common clinical features of high malignancy and poor prognosis.

CASE PRESENTATION

A 41-year-old man visited our hospital complaining of lower abdominal pain and fever. Computed tomography (CT) revealed two wall-thickening lesions in the rectum and sigmoid colon, with the latter invading the small intestine and abdominal wall. Lymph nodes were swollen in the sigmoid mesocolon and at the roots of the inferior mesenteric artery. Colonoscopy revealed a circular type 3 lesion in the sigmoid colon and a semicircular type 2 lesion in the rectum. Biopsies of the sigmoid colon and rectum lesions revealed poorly and moderately differentiated adenocarcinoma cells, respectively. The sigmoid colon, rectum, invaded small intestine, and abdominal wall were resected; lymph node dissection was also performed. Histopathological finding of the sigmoid colon lesion revealed that the tumor cells had poor connectivity with each other, and each cell had eosinophilic cytoplasm and a polymorphic nucleus. These characteristics are termed rhabdoid features, because the morphology of these cells is similar to that of rhabdomyosarcoma tumor cells. Immunohistochemical examination showed that the tumor cells were positive for both epithelial (cytokeratin AE1/AE3) and mesenchymal cell markers (vimentin); however, they were negative for integrase interactor 1 (INI1). Therefore, the sigmoid colorectal cancer was diagnosed as an INI1-negative undifferentiated carcinoma with rhabdoid features. The patient continued to experience high fever after surgery; thus, we performed an abdominal CT scan that revealed cystic lesions in the liver 4 days after surgery. These were absent in the positron emission tomography (PET)-CT scan performed 14 days before surgery. These tumors grew rapidly, and fine needle aspiration cytology revealed that they were undifferentiated carcinomas compatible with metastatic lesions from the undifferentiated carcinoma with rhabdoid features from the sigmoid colon. Chemotherapy was administered but was not effective. The patient died 60 days after surgery.

CONCLUSIONS

INI1-negative colorectal undifferentiated carcinomas with rhabdoid features are extremely rare, have high histological malignancy, and a poor prognosis. Chemotherapy is not effective. Effective systemic therapy is desired.

Loss of SMARCB1 expression in colon carcinoma

SMARCB1 is a tumor suppressor gene, which is part of SWI/SNF complex involved in transcriptional regulation. Recently, loss of SMARCB1 expression has been reported in gastrointestinal carcinomas. Our purpose was to evaluate the incidence and prognostic value of SMARCB1 loss in colon carcinoma (CC). Patients with stage III CC (n= 1695), and a second cohort of 23 patients with poorly differentiated CC were analyzed. Immunohistochemistry for SMARCB1 was performed on tissue microarrays, and cases with loss of expression were controlled on whole sections. Loss of SMARCB1 was compared with the clinico-pathological and molecular characteristics, and the prognostic value was evaluated. Loss of SMARCB1 was identified in 12 of 1695 (0.7%) patients with stage III CC. Whole section controls showed a complete loss in only one of these cases, corresponding to a medullary carcinoma. SMARCB1 loss was not associated with histological grade, tumor size nor survival. In the cohort of poorly differentiated CC, we detected 2/23 (8.7%) cases with loss of SMARCB1; one was rhabdoid while the other had medullary and mucinous histology. These 2 cases were deficient for MisMatched Repair (dMMR) and mutated for BRAF. SMARCB1 loss is rare in stage III CC, but appears more frequent in poorly differentiated CC.

BRAF Mutation in Colorectal Rhabdoid and Poorly Differentiated Medullary Carcinomas

Colorectal rhabdoid carcinomas (CRbCs) are very rare and aggressive cancers. The BRAF mutation and CpG island methylator phenotype have been reported to be common features of CRbCs. This study reviews the literature about CRbCs and analyzes the clinicopathological and molecular profiles of seven CRbCs characterized by large discohesive cells with abundant eosinophilic cytoplasm, showing hyaline inclusions and large rounded to bean-shaped nuclei. For comparison, we included four poorly differentiated medullary carcinomas (PDMCs) with focal aspects mimicking rhabdoid features. Overall survival was poor in both subsets, with 78% of patients dying of disease within 2–11 months. The main features of CRbCs were: Loss of/reduced SMARCB1/INI expression, intense vimentin immunostaining, and dense neutrophilic infiltration. The PDMCs were positive for pancytokeratin but negative for vimentin and showed moderate peritumoral/intratumoral CD8+ lymphocytes. All PDMCs showed SMARCB1(INI-1) expression. The coexistence of BRAF and TP53 mutations was observed in 80% of CRbCs and PDMCs. PDMCs always showed microsatellite instability and CpG island methylator phenotype (CIMP), while CRbCs were CIMP negative and exhibited microsatellite instability (MSI) in two out of seven cases. CRbCs are characterized by BRAF and TP53 mutations. Loss/reduced expression of nuclear SMARCB1/INI, intense vimentin immunostaining, dense neutrophilic infiltration, and low frequency of CIMP are useful markers to recognize these rare aggressive tumors.

Centrosome Linker-induced Tetraploid Segregation Errors Link Rhabdoid Phenotypes and Lethal Colorectal Cancers

Centrosome anomalies contribute to tumorigenesis, but it remains unclear how they are generated in lethal cancer phenotypes. Here, it is demonstrated that human microsatellite instable (MSI) and BRAF^V600E-mutant colorectal cancers with a lethal rhabdoid phenotype are characterized by inactivation of centrosomal functions. A splice site mutation that causes an unbalanced dosage of rootletin (CROCC), a centrosome linker component required for centrosome cohesion and separation at the chromosome 1p36.13 locus, resulted in abnormally shaped centrosomes in rhabdoid cells from human colon tissues. Notably, deleterious deletions at 1p36.13 were recurrent in a subgroup of BRAF^V600E-mutant and microsatellite stable (MSS) rhabdoid colorectal cancers, but not in classical colorectal cancer or pediatric rhabdoid tumors. Interfering with CROCC expression in near-diploid BRAF^V600E-mutant/MSI colon cancer cells disrupts bipolar mitotic spindle architecture, promotes tetraploid segregation errors, resulting in a highly aggressive rhabdoid-like phenotype in vitro Restoring near-wild-type levels of CROCC in a metastatic model harboring 1p36.13 deletion results in correction of centrosome segregation errors and cell death, revealing a mechanism of tolerance to mitotic errors and tetraploidization promoted by deleterious 1p36.13 loss. Accordingly, cancer cells lacking 1p36.13 display far greater sensitivity to centrosome spindle pole stabilizing agents in vitro These data shed light on a previously unknown link between centrosome cohesion defects and lethal cancer phenotypes providing new insight into pathways underlying genome instability.Implications: Mis-segregation of chromosomes is a prominent feature of chromosome instability and intratumoral heterogeneity recurrent in metastatic tumors for which the molecular basis is unknown. This study provides insight into the mechanism by which defects in rootletin, a centrosome linker component causes tetraploid segregation errors and phenotypic transition to a clinically devastating form of malignant rhabdoid tumor. Mol Cancer Res; 16(9); 1385-95. ©2018 AACR.

Extraordinary disease-free survival in a rare malignant extrarenal rhabdoid tumor: a case report and review of the literature

BACKGROUND

Malignant extrarenal rhabdoid tumor of the gastrointestinal tract is rarely reported in the literature. It is characterized by poor prognosis and aggressive metastatic features. A literature review evidenced only 19 cases, with poor outcome.

CASE PRESENTATION

We report a case of a colonic "pure" malignant extrarenal rhabdoid tumor with metastatic nodes in a 65-year-old Caucasian man. He was treated surgically with no recurrence, no adjuvant chemotherapy, and with 4-year survival without disease at the time of the submission of this article.

CONCLUSIONS

We present an extraordinary case of long-term survival due to the extended surgical treatment. We believe that the absence of organ metastasis at presentation is a positive prognostic factor, although pathology confirmed node involvement (13/38 positive) on microscopy.

Differential expression of CK20, β-catenin, and MUC2/5AC/6 in Lynch syndrome and familial colorectal cancer type X

BACKGROUND

Hereditary non-polyposis colorectal cancer comprises Lynch syndrome and familial colorectal cancer type X (FCCTX). Differences in genetics, demographics and histopathology have been extensively studied. The purpose of this study is to characterize their immunoprofile of markers other than MMR proteins.

METHODS

We compared the expression patterns of cytokeratins (CK7 and CK20), mucins (MUC2/5 AC/6), CDX2 and β-catenin in Lynch syndrome and FCCTX.

RESULTS

Differences were identified for CK20 and nuclear β-catenin, which were significantly more often expressed in FCCTX than in Lynch syndrome (p < 0.001), whereas MUC2, MUC5AC and MUC6 were overexpressed in Lynch syndrome tumors compared with FCCTX tumors (p = 0.001, < 0.01, and < 0.001, respectively). We observed no differences in the expression patterns of CK7 and CDX2.

CONCLUSIONS

In summary, we identified significant differences in the immunoprofiles of colorectal cancers linked to FCCTX and Lynch syndrome with a more sporadic-like profile in the former group and a more distinct profile with frequent MUC6 positivity in the latter group.

An Xp11.2 translocation renal cell carcinoma with SMARCB1 (INI1) inactivation in adult end-stage renal disease: a case report

BACKGROUND

Xp11.2 translocation/transcription factor E3 (TFE3) rearrangement renal cell carcinoma (RCC) is a rare subtype of RCC with limited clinical and pathological data.

CASE PRESENTATION

Here we present an unusual high-grade Xp11.2 translocation RCC with a rhabdoid feature and SMARCB1 (INI1) inactivation in a 40-year-old man with end-stage kidney disease. The histological examination of the dissected left renal tumor showed an organoid architecture of the eosinophilic or clear neoplastic cells with necrosis and high mitotic activity. In some areas, non-adhesive tumor cells with eccentric nuclei were observed. Immunohistochemically (IHC), the tumor cells are positive for TFE3 and the renal tubular markers (PAX2 and PAX8), and completely negative for SMARCB1, an oncosuppressor protein. Break-apart florescence in situ hybridization and reverse transcription polymerase chain reaction confirmed TFE3 rearrangement on Xp11.2 and the presence of ASPSCR1-TFE3 fusion gene. DNA sequencing revealed a frameshift mutation in exon 4 of SMARCB1 gene.

CONCLUSION

It is important to recognize this rare RCC with both TFE3 rearrangement and SMARCB1 inactivation, as the prognosis and therapeutic strategies, particularly targeted therapies for such tumors, might be different.

A Rare Case of Undifferentiated Carcinoma of the Colon with Rhabdoid Features: A Case Report and Review of the Literature

Malignant rhabdoid tumors were originally described in children. Subsequently, the same histological pattern was described in adults. Malignant rhabdoid tumors are aggressive neoplasms that have been reported in multiple organs. To our best knowledge, only 16 previous cases of rhabdoid tumor in the colon have been described in the literature. We present the case of an 87-year-old lady who was diagnosed with a rhabdoid tumor of the colon that relapsed rapidly after surgical resection. The literature concerning this unusual neoplasm was subsequently reviewed with comparison of all known cases in the literature.

Poorly differentiated cecal adenocarcinoma showing prominent rhabdoid feature combined with appendiceal mucinous cystadenoma: A case report and review of the literature

Extrarenal rhabdoid tumors (ERRTs) are extremely rare neoplasms; of these, colorectal ERRTs are the most rare, and only nine cases have been previously described in the English language literature. The current study reports the pathological features of a case of poorly differentiated cecal adenocarcinoma with prominent rhabdoid feature, which was combined with mucinous cystadenoma of the appendix in a 73-year-old male, and additionally reviews the previously reported cases. Microscopically, the majority of tumor cells were non-cohesive or loosely cohesive, with a polygonal morphology and prominent rhabdoid feature, showing eccentric vesicular nuclei, prominent nucleoli and abundant eosinophilic cytoplasm. Immunohistochemically, the tumor cells were positive for cytokeratin (CK) and vimentin, but negative for CK20, CK7, desmin and smooth muscle actin. This indicated a diagnosis of poorly differentiated adenocarcinoma with prominent rhabdoid features, combined with appendiceal mucinous cystadenoma. At two months following surgery the patient succumbed to peritoneal seeding and metastasis of liver and bone The emergence of the rhabdoid phenotype is invariably associated with an aggressive and almost always fatal clinical course. The present case is the 10th example of such a tumor in the colon, and to the best of our knowledge, this is the first case of colonic rhabdoid tumor coinciding with appendiceal benign mucinous neoplasm.

Rhabdoid carcinoma of the rectum

Rhabdoid colonic tumors are very rare lesions with just a few publications describing such neoplasms. Even more unusual for these lesions are their primary rectal locations, with only two brief case reports having been published on that subject to date. We present a case of a composite rhabdoid rectal carcinoma in a 49-year-old male. The tumor behaved very aggressively, with rapid patient demise despite radical surgery and intensive postoperative chemotherapy (FOLFIRI [folinic acid {leucovorin}, fluorouracil {5-fluorouracil}, and irinotecan] and FOLFOX4 [folinic acid {leucovorin}, fluorouraci {5-fluorouracil}, and oxaliplatin]). Pathologic examination was supportive of a rhabdoid carcinoma, with a compatible immunohistochemical profile, demonstrating synchronous expression of vimentin and epithelial markers in the tumor cells. In addition, BRAF V600E gene mutation, together with a wild-type KRAS gene, was identified, and no evidence of microsatellite instability based on MLH1, MSH2, MSH6, and PMS2 immunophenotypes, i.e., no loss of expression for all 4 markers, was observed. Our reported case confirms previously published observations of the clinical aggressiveness and the poor therapeutic response for rhabdoid tumors.

Rhabdoid colorectal carcinomas: reports of two cases

Rhabdoid colorectal carcinomas are very rare and only 10 cases have been previously reported. We report two cases of rhabdoid colorectal carcinoma, one arising in the sigmoid colon of a 62-year-old man and another in the rectum of an 83-year-old woman. In both cases, the patients had advanced tumors with lymph node metastases. The tumors mostly showed a diffuse arrangement with rhabdoid features and small glandular regions were combined. Transitional areas from the adenocarcinomas to the rhabdoid tumors were also noted. Adenocarcinoma cells were positive for mixed cytokeratin (CK), CK20 and epithelial membranous antigen (EMA), but focal positive for vimentin. The rhabdoid tumor cells were positive for mixed CK, but focal positive or negative for CK20 and EMA. In addition, they were diffusely positive for vimentin, but negative for desmin. The histological and immunohistologial findings of these two cases suggest that the rhabodid tumor cells originated from dedifferentiated adenocarcinomas.

Right-sided rhabdoid colorectal tumors might be related to the serrated pathway

BACKGROUND

Rhabdoid colorectal tumor (RCT) is a rare, highly aggressive neoplasm recurrent in elderly patients, commonly at the caecum. The molecular mechanisms underlying RCT pathogenesis remain poorly elucidated. The differential diagnosis is with the malignant rhabdoid tumors of infancy characterized by genetic inactivation of SMARCB1 (INI1) or deletions of chromosome 22q12 locus.

MATERIALS AND METHODS

To shed light on RCT pathogenesis, we investigated genetic and epigenetic alterations in two cases of pure and composite RCT and compared them with the profiles of matched adenomas and normal mucosa. Immunohistochemical analysis, FISH, methylation specific PCR and DNA sequencing analysis were performed on paraffin-embedded tissues.

RESULTS

Loss of epithelial markers, (CK20, CDX2 and E-cadherin) and intense vimentin expression was observed in RCTs but neither in the normal mucosa or adenomas. INI1 expression was detected in normal mucosa, adenomas and retained in pure RCT, while it was undetected in composite RCT. Rearrangement of the 22q12 locus was found only in pure RCT. The APC/β-catenin pathway was not altered, while MLH1 immunostaining was negative in RCTs and positive in adenomas and normal mucosa. These expression profiles were associated with V600E BRAF mutation, a progressive accumulation of promoter methylation at specific CIMP loci and additional genes from the normal mucosa to tubular adenoma and RCT.

CONCLUSIONS

Right-sided RCT could be characterized by epigenetic events and molecular features likely similar to those occurring in the serrated pathway and associated with epithelial-mesenchymal transition. These extremely rare tumors may benefit from the use of new biological molecules specific for colorectal carcinoma.

VIRTUAL SLIDES

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1641385210804556.

Genetic and epigenetic events generate multiple pathways in colorectal cancer progression

Colorectal cancer (CRC) is one of the most common causes of death, despite decades of research. Initially considered as a disease due to genetic mutations, it is now viewed as a complex malignancy because of the involvement of epigenetic abnormalities. A functional equivalence between genetic and epigenetic mechanisms has been suggested in CRC initiation and progression. A hallmark of CRC is its pathogenetic heterogeneity attained through at least three distinct pathways: a traditional (adenoma-carcinoma sequence), an alternative, and more recently the so-called serrated pathway. While the alternative pathway is more heterogeneous and less characterized, the traditional and serrated pathways appear to be more homogeneous and clearly distinct. One unsolved question in colon cancer biology concerns the cells of origin and from which crypt compartment the different pathways originate. Based on molecular and pathological evidences, we propose that the traditional and serrated pathways originate from different crypt compartments explaining their genetic/epigenetic and clinicopathological differences. In this paper, we will discuss the current knowledge of CRC pathogenesis and, specifically, summarize the role of genetic/epigenetic changes in the origin and progression of the multiple CRC pathways. Elucidation of the link between the molecular and clinico-pathological aspects of CRC would improve our understanding of its etiology and impact both prevention and treatment.

Supratentorial and spinal pediatric ependymomas display a hypermethylated phenotype which includes the loss of tumor suppressor genes involved in the control of cell growth and death

Epigenetic alterations, including methylation, have been shown to be an important mechanism of gene silencing in cancer. Ependymoma has been well characterized at the DNA copy number and mRNA expression levels. However little is known about DNA methylation changes. To gain a more global view of the methylation profile of ependymoma we conducted an array-based analysis. Our data demonstrated tumors to segregate according to their location in the CNS, which was associated with a difference in the global level of methylation. Supratentorial and spinal tumors displayed significantly more hypermethylated genes than posterior fossa tumors, similar to the ‘CpG island methylator phenotype’ (CIMP) identified in glioma and colon carcinoma. This hypermethylated profile was associated with an increase in expression of genes encoding for proteins involved in methylating DNA, suggesting an underlying mechanism. An integrated analysis of methylation and mRNA expression array data allowed us to identify methylation-induced expression changes. Most notably genes involved in the control of cell growth and death and the immune system were identified, including members of the JNK pathway and PPARG. In conclusion, we have generated a global view of the methylation profile of ependymoma. The data suggests epigenetic silencing of tumor suppressor genes is an important mechanism in the pathogenesis of supratentorial and spinal, but not posterior fossa ependymomas. Hypermethylation correlated with a decrease in expression of a number of tumor suppressor genes and pathways that could be playing an important role in tumor pathogenesis.

Rhabdoid Carcinoma of the Colon: A Distinct Entity With A Very Aggressive Behavior

Rhabdoid colon tumors (RCTs) are rare lesions whose existence as an independent distinct entity remains controversial. To date, 6 RCTs have been reported. This study reports a novel case associated with polyposis coli in a 73-year-old woman. Histologically, the neoplasia was heterogeneous consisting of an adenocarcinoma associated with rhabdoid features. In rhabdoid component, an intense expression of MSH2 was noted but MLH1 was negative. A BRAF V600E mutation and no KRAS mutations were identified. The promoter regions of subset of genes highly specific to characterize the CIMP status (NEUROG1, IGF2, RUNX3, SOCS1, including MLH1) were hypermethylated, suggesting the presence of CIMP+ and MSI high tumor. In conclusion, all RCTs have similar clinical features. The presence of polyposis and adenocarcinoma component as well as the expression of mesenchymal marker suggests a sarcomatous dedifferentiation. It is argued that RCT could be a very aggressive entity of colon, which could benefit from new biological colonic treatments.