SMARCA4 -deficient non-small cell lung cancers are usually of poor prognosis and associated with smoking-related mutations. Here, we report the case of a SMARCA4 -deficient non-small cell lung cancer (NSCLC) occurring in a non-smoker female and harboring ALK fusion. Our case highlights for physicians to be especially cautious with molecular biological results in case of SMARCA4 -deficient non-small cell lung cancer occurring in nonsmokers.

The melanin affects the pathologic diagnosis, so melanin bleaching must be performed. Our study was to investigate the effect of different melanin-bleaching methods on hematoxylin-eosin staining and immunohistochemical staining. We were used 10 malignant melanoma tissues as experimental subjects, and 3 tissues from T cell lymphoma, B cell lymphoma, neurofibroma and colon as control. Melanin was detected in all 10 malignant melanoma tissues before bleaching. Our study compared among permanganate/oxalic acid treatment, hydrogen peroxide treatment, and double oxidation treatment. The antibodies CD3 and MUM1 negative after potassium permanganate/oxalic acid treatment, but normal expression after hydrogen peroxide treatment. Antibodies CD20 and S-100 can be expressed normally after bleaching. Thus, the 10% hydrogen peroxide for 24 hours at 37°C is the mildest on melanin bleaching, its almost no effect on hematoxylin-eosin staining and immunohistochemical staining. It is suitable for different tissues and antibodies.

Histiocytic sarcoma (HS) is an extremely rare hematopoietic neoplasm derived from the monocytic/histiocytic/dendritic cell lineage. While sporadic cases of primary soft-tissue HS have been reported, its clinicopathological and molecular features remain incompletely characterized. This study investigates the clinicopathological features of two cases of soft-tissue HS and reviews the relevant literature. Microscopically, the tumor cells exhibited a diffuse growth pattern, with morphologic features varying from spindle-shaped sarcomatoid to epithelioid subtypes. Occasional bizarre cells were observed. Immunohistochemically, the tumor cells were positive for CD68, Lysozyme, S100, CD4, and CD163, but negative for a comprehensive panel of markers, including those for myeloid, Langerhans, follicular dendritic, lymphoid (T, B, NK), epithelial, vascular endothelial, and melanocytic lineages. Next-generation sequencing (NGS) revealed distinct mutational profiles: Case 1 harbored mutations in BRAF V600E, BRAF V600E, CDKN2A, and CIITA, while Case 2 exhibited mutations in CREBBP, INPP4B, RB1, PTEN, KMT2D, MSH2, and TP53, which may contribute to tumorigenesis and progression. Despite therapeutic efforts, both patients died within 6 and 9 months of follow-up, respectively. In conclusion, HS is a diagnostically challenging malignancy due to its rarity and morphological overlap with other soft tissue tumors. Immunohistochemical markers (CD68, Lysozyme, S100, CD4, CD163) are essential for diagnosis. Currently, no standard treatment exists. This study characterizes the molecular profiles of two extranodal HS cases, contributing to the understanding of their clinicopathological and genetic features.

This review summarizes the immunohistochemical profiles of dermatofibroma (DF) and dermatofibrosarcoma protuberans (DFSP) as reported by primary literature in the past 10 years. 63 studies were included in the review, with staining information for a total of 99 unique IHC markers reported. The most commonly reported stains were CD34, SMA, S100, and FXIIIa. Most studies applied IHC either to explore descriptive features of DF or DFSP or to determine their utility in diagnostic identification of the lesions. Importantly, summary data of percent positivity for key markers such as CD34 and FXIIIa highlights gaps in the existing diagnostic paradigm using these markers alone. A number of studies applied novel biomarkers that may hold promise for distinguishing DF and DFSP, namely WT1, Cx43, LSP-1, and PHH3, which demonstrated considerable expression differences between the 2 lesions. This review highlights the need for validation of existing and emerging IHC markers for the diagnosis of DF and DFSP.

As compared to most immunohistochemistry (IHC) assays, a minority of IHC tests detect loss of protein expression in tumor tissues. One may encounter unique challenges in assay optimization, validation, and standardization, illustrated here through case studies in implementing Succinate Dehydrogenase subunit B (SDHB) and H3K27me3 IHC assays. For SDHB, antibody protocols showing stronger staining in internal controls and normal tissues resulted in a staining pattern in some cases of SDH-mutated tumors that was difficult to distinguish from retained staining. For H3K27me3, some malignant peripheral nerve sheath tumors (MPNST) and non-MPNST tumors showed heterogeneous staining, with staining results differing between different autostainer platforms used. In IHC tests with loss of protein expression, antibody protocols need to account for optimal staining in internal control elements, in addition to appropriate staining in tumor cells. "Intermediate" staining patterns, such as heterogeneous or weak expression, pose a challenge for protocol calibration and diagnostic interpretation. The choice of tissue used for analytical validation is important and warrants further evaluation and guidance. Establishing an optimal balance between analytical sensitivity and analytical specificity during protocol optimization is key.

Adopting a HER2-specific treatment approach for HER2-low breast cancer has been suggested after DESTINY-Breast04 (phase 3) trials. Hence, accurate pathologic evaluation gained higher importance, making interobserver agreement and interassay agreement questionable in this regard. To evaluate these, a cohort of 116 invasive breast cancer cases were stained with Dako A0485 and Ventana 4B5. Cases were evaluated by 5 observers independently and results were compared, together with in situ hybridization findings. Interobserver agreement (Kappa) for Ventana 4B5 and Dako A0485 were 0.62 and 0.63, respectively. Agreement was more prominent for IHC 3+ cases, followed by IHC 0 cases. Comparing the assays with one another, 74 cases had the same score in Ventana 4B5 and Dako A0485, while 37 and 5 cases had higher scores in Dako A0485 and Ventana 4B5, respectively. The results of the study demonstrate that pathologists are relatively unanimous on distinguishing 3+ cases (Kappa-0.76: Ventana/0.78: Dako), but have less consistency in 1+ or 2+ cases (Kappa-0.59: Ventana/0.60: Dako). It also illustrates that the case can obtain different HER2 IHC scores with different assays being used. Therefore, it is suggested for pathologists to recognize the pitfalls in HER2 IHC, be aware of the assay that is being used in their laboratory and hence evaluate the results in the accurate context.

Cancers of unknown primary (CUP) are tumors whose site of origin remains undetectable despite thorough clinical, radiologic, and histopathologic evaluations. They make up about 2% to 3% of all epithelial tumors and generally have a poor prognosis. Immunohistochemical (IHC) markers complement epidemiological and histomorphologic approaches to determine tumor type, subtype, and primary site, influencing patient prognosis, outcome, and treatment. This retrospective observational study examined patients who underwent liver biopsies for hepatic metastasis between January 2022 and January 2024. Data on age, gender, liver segment localization, tumor number and size, histomorphology, and IHC work-up were analyzed. The average age of metastatic patients was 62±12 years, with 85.5% aged 50 or older. Males slightly outnumbered females (51.1% vs. 49.9%). On average, there were 1.8 metastatic foci per case. The most common metastasizing tumors included colorectal (30.5%), pancreaticobiliary (29%), breast (8.4%), lung (6.9%), and lymphomas (4.6%). Histomorphologically, 66.4% were adenocarcinomas, followed by poorly differentiated tumors (9.2%) and neuroendocrine neoplasms (8.4%). At the time of biopsy, 33.6% had initial CUP (i-CUP), 22.9% had their primary site detected by IHC, and 10.7% had true CUP (t-CUP). On average, 9.4 IHC markers were used per case, rising to 13.8 in t-CUP cases. Significant correlations were found between histomorphologic patterns, primary site detection, and IHC marker usage (P=0.01 and 0.02). IHC continues to enhance the diagnosis and treatment of metastatic liver tumors with its use of tumor-specific or organ-specific antibodies, including newly developed transcription factors, aiding pathologists in personalized medicine.

Gastric cancer (GC) is often diagnosed at an advanced stage, limiting treatment options and leading to poor outcomes. Klotho, a transmembrane anti-aging protein, generally functions as a tumor suppressor, while low-density lipoprotein receptor-related protein 6 (LRP6), a member of the low-density lipoprotein receptor family, is frequently overexpressed in various cancers. Klotho and LRP6 proteins are emerging regulators of Wnt/β-catenin signaling with potential roles in tumor biology. This retrospective study aimed to assess the prognostic significance of Klotho and LRP6 expression in gastric adenocarcinoma (GAC). Immunohistochemical analysis was conducted on tumor samples from 73 GAC patients. Low Klotho expression was significantly associated with younger age at diagnosis (P=0.006), poorly cohesive carcinoma (PCC) and mucinous adenocarcinoma (MAC) variants (P<0.001), diffuse type according to Lauren classification (P=0.001), high-grade tumors (P<0.001), lymph node (L.N) metastasis (P=0.038), and distant metastases (P=0.010), and advanced TNM stage (P=0.033). High LRP6 expression was significantly correlated with diffuse type (P=0.023), distant metastasis (P=0.011), and advanced TNM staging (P=0.046). Both low Klotho and high LRP6 expressions were associated with reduced overall survival (OS). Multivariate analysis identified high LRP6 expression as an independent predictor of poor OS and progression-free survival (PFS). In conclusion, low Klotho-high LRP6 expression was associated with poor OS, supporting its role as a prognostic biomarker and potential therapeutic target. Validation in larger patient cohorts is warranted to confirm their clinical utility.

Triple-negative breast cancer (TNBC) lacks specific molecular targets. This highlights an obvious need to identify specific prognostic biomarkers to stratify patients and guide treatment decisions. We designed this study to evaluate CAV1 and FOXC1 immunohistochemical expression and their correlation to survival outcomes and response to neoadjuvant chemotherapy (NAC). CAV1 and FOXC1 expressions were analyzed in 50 cases of TNBC. Clinical data on overall survival (OS), progression-free survival (PFS), and NAC response were collected and statistically evaluated. The predominant histologic subtype was invasive carcinoma of no special type (78%), with most cases being grade II (56%). CAV1 positivity was observed in 24% of cases, while FOXC1 was expressed in 74%. FOXC1 was significantly associated with higher tumor grade (P=0.02), advanced stage (P<0.001), and nodal involvement (P=0.002). It also correlated with poor NAC response and worse OS and PFS (P=0.001 and 0.01, respectively). There was a significant association of CAV1 with grade (P=0.002), lymph node involvement (P=0.003), stage (P=0.01), unfavorable clinical and pathologic response to NAC (P<0.001, P=0.01), and poor OS and PFS (P<0.001 for each). Conclusions: Both CAV1 and FOXC1 may serve as adverse prognostic indicators in TNBC. Their overexpression suggests a potential lack of benefit from NAC, indicating that targeted therapies against these markers might be more effective.

The deficiency of the current study of ccRCC lies in the incomplete understanding of the interaction between the E2F7/Beclin-1 pathway, autophagy, and EMT. This study aims to investigate the influence of the E2F7/Beclin-1 pathway on autophagy and EMT in human ccRCC.

Breast cancer (BC) is considered to be the second highest cause of cancer-related death in women. Antibodies targeting programmed death ligand 1 (PD-L1) have been approved for treating breast cancer. However, PD-L1 expression and its prognostic role in BC is still the target of several researches in order to maximize its therapeutic role in different clinicopathological settings. This study aimed to evaluate PD-L1 immunohistochemical expression in both tumor cells (TCs) and tumor-infiltrating lymphocytes (TILs) in breast carcinoma in cases with and without preoperative neoadjuvant chemotherapeutic treatment and to correlate its association with clinicopathological variables and disease-free survival (DFS). Ninety cases of breast carcinoma mastectomy specimens were collected and stained immunohistochemically for PD-L1. PD-L1 expression was evaluated in TCs and TILs in the 2 settings of cases: (group A) in which the patients did not receive preoperative neoadjuvant chemotherapy (NAC) and (group B) in which the patients received preoperative NAC. The expression of PD-L1 was correlated with clinicopathological parameters. Survival analysis was conducted to correlate disease-free survival (DFS) with PD-L1 expression. In group A, 31.1% of cases showed PD-L1 expression by TCs and 47.5% showed PD-L1 expression by TILs. In group B, 13.8% of cases showed PD-L1 expression by TCs and 41.4% showed PD-L1 expression by TILs. PD-L1 expression in both TCs and TILs is significantly associated with poor prognostic factors in breast cancer. In cases with residual cancer after neoadjuvant chemotherapy, PD-L1 expression remains prominent in TILs, suggesting ongoing immune resistance.

New markers are needed to aid in the diagnosis, typing, and determination of targeted treatment options in Hodgkin lymphoma. STAT6 is one of the most frequently reported mutations in classic Hodgkin tumors and can also be detected immunohistochemically. Our study aimed to investigate the role of the STAT6 (EP325) immunostain, diagnosing Hodgkin lymphoma, its staining frequency, immunolocalization, and its relationship with EBV. Sixty-eight patients representing each Hodgkin lymphoma subtype were included in the study. Two patients had nodular lymphocyte-predominant type Hodgkin, 32 had nodular sclerosis, 14 had mixed type, 10 had lymphocyte-depleted, and 10 had lymphocyte-rich type Hodgkin subtypes. STAT6 (EP325), CD30 (Ber-H2), EBV (CS.1-4) immunohistochemistry, EBER CISH and H&E slides applied to the tumors were examined. STAT6 was positive in 90% (61/68) of all lymphomas. Immunoreactivity with STAT6 was present in all tumors of the nodular sclerosis and lymphocyte-depleted subtypes. A total of 10/14 (71%) of mixed cell subtype tumors and 9/10 (90%) lymphocyte-rich subtype tumors were STAT6 positive. STAT6 staining was not detected in 2 (100%) nodular lymphocyte-predominant subtype. A total of 31% (19/61) of STAT6-positive tumors were also positive for EBV. While STAT6 positivity may be diagnostic of classic Hodgkin's subtypes, STAT6 negativity may be useful for diagnosis of nodular lymphocyte predominant type.

Indoleamine 2,3-dioxygenase 1 (IDO1) is an immune regulator involved in innate and acquired immunity and immune escape of tumors. Its expression in the tumor microenvironment of several solid tumors and lymphomas associated with Epstein-Barr virus (EBV), together with the promising results from clinical trials of IDO1 inhibitors, prompted us to evaluate IDO1 expression in a large cohort of 455 lymphomas including 154 cases associated with EBV. We optimized an immunohistochemical assay to evaluate IDO1 staining and show that IDO1 expression in seen in several lymphoma subtypes including classic Hodgkin lymphoma (CHL, 40%), diffuse large B-cell lymphoma (DLBCL, 23.5%), lymphoproliferative disorders in post-transplant settings (LPD-PT, 71.4%), extranodal NK/T-cell lymphoma (ENKTL, 92%), and ALK-negative anaplastic large cell lymphoma (ALCL, 39%), among others. Multiplex immunofluorescence further aided in refining the localization of IDO1 protein expression particularly within the tumor microenvironment. There was a significant correlation between IDO1 expression and EBV positivity in CHL (83.8%), LPD-PT (86.2%), and ENKTL (91.5%), with statistically significant difference in the mean IDO1 H-scores between EBV-positive and EBV-negative cases. IDO1 expression in ALCL was confined to ALK-negative cases with a significant correlation between IDO1 expression and ALK status. Our findings show that IDO1 expression is not only highly correlated with lymphomas associated with EBV, but also found in lymphomas unassociated with EBV, including aggressive and refractory subtypes of lymphomas for which immune checkpoint inhibition through IDO1 could be exploited for therapeutic purposes.

Dedifferentiated liposarcoma (DDLPS) is a high-grade tumor characterized by its diverse histomorphology and development from atypical lipomatous tumor/well-differentiated liposarcoma (ALT/WDLPS). The variable morphology of DDLPS, particularly its similarity to myxoid LPS, necessitates a reliable diagnostic tool for accurate diagnosis. While DDIT3 rearrangement is a known characteristic of myxoid LPS, its amplification in DDLPS has not been extensively studied. To investigate this, we evaluated DDIT3 amplification in 29 DDLPS cases from Asan Medical Center over a 7-year period using fluorescence in situ hybridization, with immunohistochemistry for MDM2 and CDK4 performed for diagnostic confirmation. Our findings revealed DDIT3 amplification in 89.7% (26/29) of DDLPS cases, with a mean copy number of 7.4. While no significant differences in clinical characteristics or outcomes were observed between patients with and without DDIT3 amplification, patients with <4 copies of DDIT3 amplification showed a tendency toward shorter disease-free survival. These findings demonstrate the prevalence of DDIT3 amplification in DDLPS, suggesting its potential diagnostic and therapeutic significance. Additional research is necessary to fully understand the prognostic implications of DDIT3 amplification levels in DDLPS and its potential application in targeted therapies.

To investigate the clinicopathological characteristics of non-HPV-related common differentiated penile squamous cell carcinoma, and to observe and analyze the changes of TP53 gene and the expression and significance of TP53, P16, programmed death-ligand 1 (PD-L1), epidermal growth factor receptor (EGFR), androgen receptor (AR), human epidermal growth factor receptor-2 (HER2), and Ki67 proteins in tumor tissue. A total of 65 patients with penile squamous cell carcinoma diagnosed from May 2008 to May 2020 in Yantai Yuhuangding Hospital were retrospectively analyzed, and tumors were confirmed as non-HPV-associated common differentiated squamous cell carcinoma of the penis with negative HPV molecular tests in 55 patients. The relevant clinicopathological data of 55 patients were collected, and the TP53 gene mutation was detected by applying first-generation sequencing technology. And tumor tissue microarrays were prepared, and further immunohistochemical EnVision 2-step method was used to detect the expression levels of 7 of these proteins: TP53, P16, PD-L1, EGFR, AR, HER2, and Ki67. Pathologic grading non-HPV-associated common differentiated penile squamous cell carcinoma of 55 patients was G1 in 22 patients, G2 in 28 patients, and G3 in 5 patients. The tumor pathologic stage was pT1 in 22 patients, pT2 in 26 patients, pT3 in 6 patients, and pT4 in 1 case. Immunohistochemical markers showed positive expression of TP53 protein in about 84% (46/55 patients) and strong positive expression in about 20% of patients (11/55 patients), and the expression level of this protein was closely related to the pathologic grade and stage of the tumor. All patients showed negative expression of P16 protein. PD-L1 protein-positive expression patients accounted for about 35% (19/55 patients), among whom strong positive expression patients accounted for 20% (11/55 patients), and there was a correlation between PD-L1 protein expression level and the maximum tumor diameter. EGFR protein was positively expressed in 76% (42/55 patients) of patients and confirmed a significant correlation with the pathologic grade and stage of the tumor. The percentage of Ki67 protein-positive expression patients was 58% (32/55 patients) and significantly correlated with tumor pathology grade. In contrast, AR and HER2 proteins were negative in all 55 tumors. In 55 patients, except for 10 patients with failed DNA extraction, the mutation rate of TP53 gene in the remaining 45 patients was about 33% (15/45 patients), and the mutation sites were mainly concentrated in exon 5, followed by exon 8 and exon 5/8 combined mutation, and occasionally in exon 7/8 combined mutation. TP53 gene mutations were present in all positive TP53 protein expression intervals, and the highest rate of TP53 gene mutations was found in patients with ≥80% strong positive expression of TP53 protein, about 67% (6/9 patients). In addition, statistical analysis revealed a significant positive correlation between TP53 and Ki67 protein expression, and a low correlation between TP53 and EGFR protein, PD-L1 and Ki67, and EGFR and Ki67 protein. Non-HPV-associated common differentiated squamous cell carcinoma of the penis currently dominates the morbidity, with relatively good pathologic grading/staging and prognosis for most tumors, with a few being poor. TP53 mutations play an important role in the pathogenesis of this tumor, but TP53 mutations do not always coexist with TP53 protein overexpression. The combination of 3 proteins, TP53, P16, and Ki67, are useful antibodies for adjuvant staging and prognosis of penile squamous cell carcinoma. PD-L1 and EGFR are important new biological targets for adjuvant therapy in non-HPV-associated common differentiated squamous cell carcinoma of the penis, whereas AR and HER2 proteins were not clearly targeted in all patients. In conclusion, the combined detection of 5 proteins, TP53, P16, PD-L1, EGFR, and Ki67, in addition to AR and HER2, is important for the precise diagnosis and prognosis analysis of non-HPV-associated common differentiated squamous cell carcinoma of the penis.

Monoamine oxidases (MAOs) produce hydrogen peroxide through an oxidative reaction and mediate the production of reactive oxygen species. MAO expression has been correlated with the prognosis in several tumor types. Accordingly, we aimed to evaluate MAOA and MAOB expression in patients with colorectal cancer (CRC) using immunohistochemistry as well as to assess their clinicopathologic behavior and prognostic significance. High MAOB expression (169 patients, 51.7%) was significantly associated with poor tumor differentiation, high pT classification, presence of lymphovascular invasion, lymph node metastasis, distant metastasis, and high MAOA expression. MAOA expression (245 patients, 74.9%) was not significantly correlated with any other clinicopathologic factors. Patients with high MAOB expression had significantly worse overall survival than those with low MAOB expression [hazard ratio (HR)=2.974; 95% CI: 1.855-4.767; P<0.001]. MAOA expression was not significantly correlated with overall survival in patients with CRC. Further, high MAOB expression (HR=1.680; 95% CI: 1.014-2.784; P=0.044) was an independent poor prognostic factor in patients with CRC. In conclusion, high MAOB expression is correlated with aggressive clinicopathologic behavior and may be a poor prognostic marker in patients with CRC.

Esophageal squamous cell carcinoma (ESCC), a commonly diagnosed cancer, poses challenges for early detection due to differentiation difficulties.

This study aimed to gain insight into cancer progression and the metastatic process by analyzing protein expression patterns in primary, metastatic, and nonmetastatic tongue squamous cell carcinoma (TSCC), with a focus on understanding biomarker changes between primary tumors and lymph node metastases. A total of 60 TSCC biopsy samples, 20 primary metastatic, 20 lymph node metastatic, and 20 nonmetastatic, were immunohistochemically stained to analyze MCM2, CD44, and E-cadherin expression. Expression levels were assessed through immunoreactivity scores, and differences across groups were evaluated using generalized estimating equations (GEE). No significant differences in biomarker expression were observed between primary tumors and their lymph node metastases. However, significant variations were identified in MCM2 and E-cadherin expression across the groups. MCM2 expression was notably lower in lymph node metastases compared with nonmetastatic TSCC ( P = 0.025), and E-cadherin expression was reduced in primary tumors relative to nonmetastatic samples ( P = 0.028). CD44 expression did not show significant variation across the different groups. The results align with the classic model of TSCC metastasis, suggesting biomarker stability between primary and metastatic sites. However, variations in MCM2 and E-cadherin expression between specific groups highlight their potential roles in TSCC progression. Further investigation into additional markers and pathways could offer a more comprehensive understanding of TSCC metastasis and contribute to more precise therapeutic approaches.

Signet ring cell carcinoma (SRCC) and adenocarcinoma (ADC) exhibit distinct characteristics, yet a comprehensive comparison is lacking. In this retrospective study from 2020 to 2024, we analyzed 568 gastric cancer cases, including 216 SRCC and 352 ADC. In SRCC, MMR deficiencies were 3.2% for MLH1, 2.3% for PMS2, 0.5% for MSH2, with PMS2 deficiencies more prevalent in old patients and only one MSH2 deletions observed in cardia-involved cases. E-cadherin loss was 13.5%, predominantly in males and cases with nerve invasion, while Claudin18.2 positivity was 49.2%, particularly in early-stage patients. In ADC, MMR deficiencies were 8.5% for MLH1, 6.5% for PMS2, 0.3% for MSH6 and MSH2, with MLH1 and PMS2 deficiencies more common in females, old patients, and antrum-involved cases, and MSH2 deletions associated with larger tumors. E-cadherin loss was 5%, primarily in poorly differentiated and diffuse types, and Claudin18.2 positivity was 50.9%, especially in lymphatic metastasis patients. SRCC was more common in females and younger individuals, peaking 10 years earlier than ADC, which was significantly more prevalent in males. Both localized predominantly in the antrum. SRCC exhibited mucosa and serosa infiltration along with higher local metastasis, while ADC showed gradually increasing infiltration depth. MLH1 and PMS2 deficiencies were more common in ADC, while E-cadherin loss predominantly in SRCC. AB-PAS expression was higher in SRCC. Female and elderly were risk factors for MMR deficiencies in ADC, while female protected against E-cadherin loss in SRCC. These results highlight the need for tailored therapeutic approaches based on distinct molecular and clinical features.