OBJECTIVE: Urothelial carcinoma has various molecular subtypes, each with different tumor characteristics. Although it is known that molecular changes occur during tumor progression, little is known about the specifics of these changes. In this study, we performed transcriptional analysis to understand the molecular changes during tumor progression.
METHODS: Formalin-fixed, paraffin-embedded tumor tissues were obtained from 12 patients with muscle-invasive bladder cancer (MIBC). The invasive and non-invasive papillary areas were identified in papillary urothelial carcinoma specimens. Immunohistochemistry (IHC) and mRNA sequencing were performed for each tumor area.
RESULTS: Patients with CK5/6-negative and CK20-positive non-invasive papillary areas were selected and classified into the IHC switch subgroup (CK5/6-positive and CK20-negative in the invasive area) and the IHC unchanged subgroup (CK5/6-negative and CK20-positive in the invasive area) according to the IHC results of the invasive area. We identified differences in the mRNA expression between the non-invasive papillary and invasive areas of the papillary MIBC tissue samples. In both the non-invasive papillary and invasive areas, the IHC switch subgroup showed basal subtype gene expression, while the IHC unchanged subgroup demonstrated luminal subtype gene expression.
CONCLUSIONS: The non-invasive papillary area showed a gene expression pattern similar to that of the invasive area. Therefore, even if the non-invasive papillary area exhibits a luminal phenotype on IHC, it can have a basal subtype gene expression depending on the invasive area.

Few studies have evaluated cytokeratin\'s (CK) staining patterns in atypical endometrial hyperplasia (AEH) coexisting with early-stage endometrial cancer (EC). We aimed to assess the staining patterns of selected CKs (CK7, CK19, CK20, CK AE1/AE3) in 74 patients with coexisting AEH and EC by independently analyzing both morphological variables. Specimens were collected from women with AEH and EC who underwent surgical interventions between 2012 and 2019 at the Department of Obstetrics and Gynecology of Vilnius University Hospital \"Santaros Klinikos\" in Vilnius, Lithuania. Immunostaining was also qualitatively classified as being heterogeneous or intense. The results revealed heterogeneous CK7 expression in all AEH cases and intense staining in 95.95% cases of AEH. The heterogeneous expression of CK7 was detected in all EC specimens. Intense CK7 expression was observed in 95.09% cases of EC G1 and in all G2 ECs. Heterogenous CK19 expression was present in all AEH specimens with intense staining in 92.42% of cases. Heterogeneous CK19 expression was observed in all EC samples with intense expression in 86.27% cases of EC G1 and 100% cases of EC G2. Interestingly, a significant relationship was found when comparing the heterogeneous expression of CK19 between AEH and well-differentiated EC. A significant difference was reported in the intense expression of CK AE1/AE3 (p = 0.031; p = 0.029) between AEH and G2 ECs and in the intense expression of CK AE1/AE3 between G1 and G2 ECs. CK20 staining was not a characteristic feature for AEH and early-stage EC. CK staining is present either in AEH or in early-stage endometrioid-subtype EC in different manners. Heterogeneous CK19 expression was significantly more common in AEH than in EC. CK20 expression was not associated with either AEH nor early-stage EC. An intense expression of CK AE1/AE3 was mainly present in moderately differentiated ECs, whereas the intense reactivity of AE1/AE3 showed a significant difference in well to moderately differentiated uterine tumors. The clinical implication of CK staining may aid in the more accurate diagnosis of AEH and early-stage EC as well as detect micrometastases leading to better oncological outcomes.

BACKGROUND: Cytokeratins (CKs) have been associated with precancerous and cancerous gastric lesions in patients with Helicobacter pylori-associated chronic gastritis, making them useful for diagnosing epithelial tumors.
METHODS: A retrospective study was conducted utilizing 200 formalin-fixed paraffin-embedded gastric biopsy samples collected from the lesser curvature of the stomach. Samples from the control group, patients with H. pylori infection, and patients with H. pylori-associated gastritis, with complete and incomplete intestinal metaplasia (IM) were immunostained. Monoclonal antibodies were utilized to determine the expression of CK7, CK20, and Ki-67.
RESULTS: Patients infected with H. pylori had strong CK20 expression on the surface, and weak CK7 expression on the surface and deep glands; while non-specific chronic gastritis patients had weak focal CK7 expression and strong CK20 expression. The normal gastric mucosa of patients in the control group had relatively weak CK7 expression, restricted to a few cells in the neck and deep glands. CK20 showed diffuse strong reactivity on the surface. On the other hand, patients with complete IM showed a CK7 staining pattern that was either negative or weakly focal on the surface and crypts associated with diffuse surface CK20 and focal crypt staining corresponding to gastric type IM. The Ki67 proliferating index was low (≤ 15%) in H. pylori infected patients, high (> 30%) in patients with incomplete IM, and intermediate (16-30%) in patients with complete IM.
CONCLUSIONS: These results indicate a significant link between the expressions of CK7/CK20 and Ki67 in patients afflicted with H. pylori and IM.

SATB2 has been reported to be highly specific for lower gastrointestinal tract tumors. On the basis of its ileum-colon conversion effects, which involve the activation of colonic genes in cooperation with CDX2 and HNF4A, we hypothesized that SATB2 and CDX2 might define the characteristics of colorectal cancers (CRCs). In the present study, the clinicopathologic and immunohistochemical characteristics of 269 CRCs were analyzed according to SATB2 and CDX2 expression. CRCs with SATB2- and/or CDX2- phenotypes showed associations with poorly differentiated histotypes ( P <0.00001), mucus production ( P =0.0019), and mismatch repair-deficient phenotypes ( P <0.00001). SATB2-/CDX2- CRCs were significantly associated with CK20-negativity, with or without CK7 expression ( P <0.00001), as well as with MUC5AC-positivity ( P <0.00001), and CD10-negativity ( P =0.00047). Negativity for SATB2 or CDX2 was associated with the expression of PD-L1 in both all CRC ( P <0.00001) and mismatch repair-proficient CRC ( P =0.000091). Multivariate Cox hazard regression analysis identified negativity for SATB2 and/or CDX2 as potential independent risk factors for patients with CRC. Regarding the diagnostic utility of SATB2, all of the 44 CRC metastases could be diagnosed as colorectal in origin if the immunohistochemical phenotypes (including CK7, CK20, and p53) of the primary lesions and patient history were considered. Among the other 684 tumors, we were unable to distinguish a case of CK7-/CK20+/CDX2+/SATB2+ ovarian mucinous cystadenocarcinoma from metastatic CRC without the patient history and clinical information.

Primary mucinous tumors of the renal pelvis are extremely rare and pose challenges in terms of diagnosis and treatment. This study reviewed the clinical and pathological characteristics of mucinous tumors of the renal pelvis, including mucinous cystadenocarcinomas and mucinous cystadenomas. Immunohistochemical analysis was conducted in three cases, along with KRAS gene detection using the Amplification Refractory Mutation System (ARMS) method. The results revealed mucinous epithelium with acellular mucinous pools in all cases, and acellular mucinous pools were observed in the renal parenchyma and perirenal fat capsules. All tumors expressed CK20 and CDX2, and one case showed KRAS gene mutation. The study suggests that mucinous cystadenomas of the renal pelvis may exhibit borderline biological behaviors. This study is the first to report a KRAS gene mutation in a mucinous cystadenoma of the renal pelvis, offering valuable insights into the diagnosis and treatment of this rare condition.

Upper tract urothelial carcinoma (UTUC) presents diagnostic challenges due to small biopsy specimen size, poor orientation, and technical obstacles that can yield equivocal diagnoses. This uncertainty often mandates repeated biopsies to evaluate the necessity of nephroureterectomy. Prior studies have suggested cytokeratin 17 (CK17) immunostain as an adjunctive tool for diagnosing bladder urothelial neoplasia in both urine cytology and tissue biopsy specimens. We evaluated the utility of CK17 in differentiating UTUC from benign urothelium and its ability to stratify low-grade from high-grade neoplasia. Our study involved a cohort of previously diagnosed cytology (n = 29) and tissue specimens from biopsies and resections (n = 85). We evaluated CK17 staining percentage in cytology and tissue samples and localization patterns in biopsy/resection samples. Our findings showed a statistically significant distinction (p < 0.05) between UTUC and benign tissue specimens based on full thickness localization pattern (odds ratio 8.8 [95% CI 1.53-67.4]). The percentage of CK17 staining failed to significantly differentiate neoplastic from non-neoplastic cases in cytology or tissue samples. Additionally, based on prior research showing the efficacy of CK20/CD44/p53 triple panel in bladder urothelial neoplasia, we utilized tissue microarrays to evaluate if these markers could distinguish UTUC from benign urothelium. We found that CK20/CD44/p53, individually or in combination, could not distinguish urothelial neoplasia from non-neoplasia. Full thickness CK17 urothelial localization by immunohistochemistry was highly reproducible with excellent interobserver agreement and may play a supplementary role in distinguishing upper tract urothelial neoplasia from benign urothelium.

BACKGROUND: Aberrant expression of CK7/CK20/CDX2 is reported in percentage of colorectal carcinomas (CRC).

BACKGROUND: Hematological recurrence is the second most frequent cause of failure in the treatment of gastric cancer. The detection of circulating tumor markers in peripheral blood by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) method may be a useful tool to predict recurrence and determine the patient\'s prognosis. However, no consensus has been reached regarding the association between the tumor markers level in peripheral blood and its impact on patient survival.
OBJECTIVE: To evaluate the expression of the circulating tumor markers CK20 and MUC1 in peripheral blood samples from patients with gastric cancer by qRT-PCR, and to verify the association of their expression levels with clinicopathological characteristics and survival.
METHODS: A total of 31 patients with gastric adenocarcinoma were prospectively included in this study. CK20 and MUC1 expression levels were analyzed from peripheral blood by the qRT-PCR technique.
RESULTS: There was no statistically significant (p>0.05) association between CK20 expression levels and clinical, pathological, and surgical features. Higher MUC1 expression levels were associated with female patients (p=0.01). There was a correlation between both gene levels (R=0.81, p<0.001), and CK20 level and tumor size (R=0.39, p=0.034).
CONCLUSIONS: CK20 and MUC1 expression levels could be assessed by qRT-PCR from total peripheral blood samples of patients with gastric cancer. CK20 levels were correlated to MUC1 levels as well as to tumor size. There was no difference in disease-free survival and overall survival regarding both genetic markers expression in this series.

BACKGROUND: The histological subtype is an important prognostic factor for ampulla of Vater (AoV) cancer. This study proposes a classification system for the histological subtyping of AoV cancer based on immunohistochemical (IHC) staining and its prognostic significance.
METHODS: Seventy-five AoV cancers were analyzed for cytokeratin 7 (CK7), CK20, and causal-type homeobox transcription factor 2 (CDX2) expression by IHC staining. We differentiated the subtypes (INT, intestinal; PB, pancreatobiliary; MIX, mixed; NOS, not otherwise specified) into classification I: CK7/CK20, classification II: CK7/CK20 or CDX2, classification III: CK7/CDX2 and examined their associations with clinicopathological factors.
RESULTS: Classifications I, II, and III subtypes were INT (7, 10, and 10 cases), PB (43, 37, and 38 cases), MIX (13, 19, and 18 cases), and NOS (12, 9, and 9 cases). Significant differences in disease-free survival among the subtypes were observed in classifications II and III using CDX2; the PB and NOS subtype exhibited shorter survival time compared with INT subtype. In classification III, an association was revealed between advanced T/N stage, poor differentiation, lymphovascular invasion (LVI), the PB and NOS subtypes, and recurrence risk. In classification III, the subtypes differed significantly in T/N stage and LVI. Patients with the PB subtype had advanced T and N stages and a higher incidence of LVI.
CONCLUSIONS: Classification using CDX2 revealed subtypes with distinct prognostic significance. Combining CK7 and CDX2 or adding CDX2 to CK7/CK20 is useful for distinguishing subtypes, predicting disease outcomes, and impacting the clinical management of patients with AoV cancer.

Histopathological evaluation of lymph nodes in Merkel cell carcinoma has become crucial in progression estimation and treatment modification. This study was undertaken to determine the most sensitive immunohistochemical panel for detecting MCC nodal metastases. We included 56 patients with 102 metastatic MCC lymph nodes, which were tested with seven antibodies: cytokeratin (CKAE1/AE3), CK20, chromogranin A, synaptophysin, INSM1, SATB2, and neurofilament (NF). Tissue microarrays (TMA) composed of 2-mm tissue cores from each nodal metastasis were constructed. A semiquantitative 5-tier scoring system (0%, < 25%, 25-74%, 75-99%, 100% positive MCC cells with moderate to strong reactivity) was implemented. In the statistical assessment, we included Merkel cell polyomavirus (MCPyV) status and expression heterogeneity between lymph nodes from one patient. A cumulative percentage of moderate to strong expression ≥ 75% of tumoral cells was observed for single cell markers as follows: 91/102 (89.2%) SATB2, 85/102 (83%) CKAE1/AE3, 80/102 (78.4%) synaptophysin, 75/102 (75.5%) INSM1, 68/102 (66.7%) chromogranin A, 60/102 cases (58.8%) CK20, and 0/102 (0%) NF. Three markers presented a complete lack of immunoreactivity: 8/102 (7.8%) CK20, 7/102 (6.9%) chromogranin A, and 6/102 (5.9%) NF. All markers showed expression heterogeneity in lymph nodes from one patient; however, the most homogenous was INSM1. The probability of detecting nodal MCC metastases was the highest while using SATB2 as a first-line marker (89.2%) with subsequential adding CKAE1/AE3 (99%); these results were independent of MCPyV status. Synaptophysin showed a superior significance in confirming the neuroendocrine origin of metastatic cells. This comprehensive analysis allows us to recommend simultaneous evaluation of SATB2, CKAE1/AE3, and synaptophysin in the routine pathologic MCC lymph node protocol.