Navigating HER2-Low Testing in Invasive Breast Cancer: Update Recommendations for Pathologists.

The article discusses the importance of accurately distinguishing HER2-low from HER2-negative breast cancer, as novel ADCs have demonstrated activity in a large population of patients with HER2-low-expressing BC. While current guidelines recommend a dichotomous classification of HER2 as either positive or negative, the emergence of the HER2-low concept calls for standardization of HER2 testing in breast cancer, using currently available assays to better discriminate HER2 levels. This review covers the evolution and latest updates of the ASCO/CAP guidelines relevant to this important biomarker in breast cancer, including still-evolving concepts such as HER2 low, HER2 heterogeneity, and HER2 evolution. Our group presents the latest Mexican recommendations for HER2 status evaluation in breast cancer, considering the ASCO/CAP guidelines and introducing the HER2-low concept. In the era of personalized medicine, accurate HER2 status assessment remains one of the most important biomarkers in breast cancer, and the commitment of Mexican pathologists to theragnostic biomarker quality is crucial for providing the most efficient care in oncology.

Anaplastic large cell lymphoma with ALK::ATIC fusion mimicking a histiocytic sarcoma debuting as an anterior thoracic soft tissue tumor with exceptional clinicopathological, morphological and molecular features.

A 56-year-old woman debuted with a palpable painless mass in the anterior thorax wall at the level of the second and third right parasternal intercostal space, which progressively increased in size over 5 months accompanied by localized skin rash, mild dyspnea and chest pain when changing position. Imaging studies showed a soft tissue mass measuring 75 × 62 mm and a density of 34 Hounsfield Units that had caused the lysis of the costal arches and grew expansively towards the anterior mediastinum, without identifying mediastinal adenopathies only by this imaging method. Core biopsy was performed, which was initially diagnosed as histiocytic sarcoma (HS); however, when the diagnostic panel was expanded to include molecular and NGS studies, the final diagnosis was anaplastic large cell lymphoma with ALK::ATIC fusion. Here, we report a very rare neoplasm with unusual clinical presentation, histopathology and molecular features.

[Large cell carcinoma of the lung with null immunophenotype: Case report & brief review]. / Carcinoma de células grandes de pulmón con inmunofenotipo nulo: reporte de caso y revisión breve de la literatura.

Large cell carcinoma of the lung with null-immunophenotype (LCC-NI) is a diagnostic entity that is especially uncommon now as it does not have any type of cell differentiation or its own molecular alterations. It presents an exceptional diagnostic challenge; indeed, the diagnosis is only possible with complete surgical excision and adequate immunohistochemical and molecular studies. We report the case of a 69-year-old male, with a history of long-term smoking who presented with pleuritic pain. A tumor in the upper lobe of the right lung was detected and removed by lobectomy. Histopathology revealed a neoplasm with large cell morphology without any specific immunophenotype, molecular or genomic rearrangements through next-generation sequencing (NGS) studies, which was diagnosed as LCC-NI.

Intestinal-type adenocarcinoma arising from a villous adenoma in the renal pelvis in the context of a kidney abscess: Case report.

Villous adenoma is a benign neoplasm with an exceptional presentation in the renal pelvis, hence very few cases have been reported. Herein we present the case of a patient who presented with left flank pain clinically suggestive of complicated pyelonephritis, culminating in simple nephrectomy with a villous adenoma in the renal pelvis as histopathological finding associated to the presence of a microscopic focus of intestinal-type adenocarcinoma.

Selective efficacy and safety of first line and non front line antineoplasic agent combinations determined with individualized assays on colorectal cancer primary cultures.

PURPOSE: To evaluate the efficacy of first-line and not-conventional antineoplastic drug combinations in colorectal adenocarcinoma primary cultures (CRAC PCs). METHODS: The efficacy and safety of 21 drug combinations (DCs) were evaluated using a simplified adenosine triphosphate-based chemotherapy response assay (sATP-CRA). The efficacy of each DC was reported as the percentage of cell death (PCD) produced on each of 12 CRAC-PCs, and the safety of each DC was evaluated as a safety window (SW). The SW was calculated as the quotient of PCD-CRAC PC/PCD-hMSC-TA (human mesenchymal stem cells derived from adipose tissue). Nine DCs contained 5-fluorouracil and oxaliplatin, and 1-3 non-front line drugs (NFLDs [carboplatin, doxorubicin, cisplatin, aspirin, or 3,3' diindolylmethane]). The other 11 DCs only contained 2-4 NFLDs. RESULTS: The efficacy and safety each DC were highly variable and depended on each CRAC PC and DC. The usefulness of DCs was considered as a combination of PCD >20 and an SW >0.6: 13 /21 DCs (62%) met the requirements of efficacy and safety on 7/12 CRAC PCs (58.3%). CONCLUSIONS: The resistance to 5-fluorouracil/oxaliplatin of CRAC PCs and the usefulness of seven new DCs strongly suggest the convenience of performing ex vivo individualized assays to evaluate DCs, and implement new and more useful treatments, instead of submitting patients to standardized chemotherapies in a blinded manner. Approaches such as this and properly evaluated in clinical assays could increase the life expectancy of patients with cancer and improve their quality of life.

Local secretion of stress hormones increases in alopecia areata lesions after treatment with UVA-1 phototherapy.

Alopecia areata (AA) is an autoimmune disease of the hair follicle. Keratinocytes of the hair follicle generate an immunosuppressive environment by the local secretion of hormones of the hypothalamic-pituitary-adrenal axis of the skin (skin HPA analog). Our objective was to measure the local production of corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH), and α-melanocyte-stimulating hormone (α-MSH) in the scalp tissue of patients with AA before and after ultraviolet A1 (UVA-1) phototherapy to determine their role in the pathogenesis of AA and the effect of UVA-1 on the AA hormonal environment. This was a retrospective and descriptive study of skin samples from 22 patients with AA before and after UVA-1 treatment. We compared the changes in the local hormonal environment by measuring CRH, ACTH, type 2 melanocortin receptor (ACTH receptor) and α-MSH with immunohistochemical stains. The positivity of MSH was significantly higher (P = .037) in the post-treatment samples compared with the baseline value. ACTH was significantly higher in intensity (P = .032) in the post-treatment samples compared with the initial value. CRH was significantly higher in intensity (P = .013) in baseline samples compared with the final biopsies. The positivity of the ACTH receptor MC2R was not different between the two groups (P = .626). In AA, an interruption in the signalling of CRH could decrease the local concentration of ACTH and MSH, and consequently, the immunosuppressive effect of these hormones. This phenomenon is normalized in the skin treated with UVA-1. A defective signalling system in the cutaneous HPA axis may be involved in the pathogenesis of AA.

Thymidylate synthase polymorphism in Mexican patients with colon cancer treated with 5-fluorouracil.

PURPOSE: We analyzed the genotype and allele frequency of variable number tandem repeats (VNTR)-thymidylate synthase (TS) and its relationship with the disease evolution in colon cancer patients. METHODS: We selected 24 paraffin-embedded colon cancer tissue samples from Mexican patients who received a 5-fluorouracil (5-FU)-based chemotherapy regimen. Tumor tissue was digested with proteinase K and genomic DNA was isolated by the standard method with phenol-chloroform extraction. Polymerase chain reaction (PCR) was performed for TS genotyping of VNTR and the results were evaluated directly in a stained agarose gel. RESULTS: The allele frequency of 2 repeats (2R) was greater (0.66) than 3R (0.34) in metastatic colon cancer (x2=10.24; p=0.001)) however, no difference in allelic distribution between 2R (0.54) and 3R (0.46) in non metastatic patients was observed (x2=0.640; p=0.424). CONCLUSION: Our results suggest that Mexican patients with colon cancer present differences in the allelic distribution, the 2R allele being the most frequent.

CDX-2, MUC-2 and B-catenin as intestinal markers in pure mucinous carcinoma of the breast.

BACKGROUND: Pure mucinous adenocarcinoma of the breast is a rare entity characterized by the production of variable amounts of mucin comprising 1% to 6% of breast carcinomas. Some mucinous adenocarcinomas have shown expression of intestinal differentiation markers such as MUC-2. This study examines the expression of intestinal differentiation markers in this type of breast carcinoma. RESULTS: Twenty-two cases of pure mucinous adenocarcinoma of the breast were assessed. Immunochemistry was performed for beta-catenin, CDX-2 and MUC-2. All cases were positive for B-catenin. MUC-2 positivity was observed in all cases; 63. 6% were 3 plus positive. All cases were negative for CDX-2. CONCLUSIONS: These results suggest that mucinous breast carcinomas express some markers of intestinal differentiation, such as MUC-2 and beta-catenin; however, future studies with a larger series of cases and using molecular techniques that help affirm these results are needed.

CDX-2, MUC-2 and B-catenin as intestinal markers in pure mucinous carcinoma of the breast

BACKGROUND: Pure mucinous adenocarcinoma of the breast is a rare entity characterized by the production of variable amounts of mucin comprising 1% to 6% of breast carcinomas. Some mucinous adenocarcinomas have shown expression of intestinal differentiation markers such as MUC-2. This study examines the expression of intestinal differentiation markers in this type of breast carcinoma. RESULTS: Twenty-two cases of pure mucinous adenocarcinoma of the breast were assessed. Immunochemistry was performed for beta-catenin, CDX-2 and MUC-2. All cases were positive for B-catenin. MUC-2 positivity was observed in all cases; 63. 6% were 3 plus positive. All cases were negative for CDX-2. CONCLUSIONS: These results suggest that mucinous breast carcinomas express some markers of intestinal differentiation, such as MUC-2 and beta-catenin; however, future studies with a larger series of cases and using molecular techniques that help affirm these results are needed.

TSPAN33 is a novel marker of activated and malignant B cells.

We have identified Tspan33 as a gene encoding a transmembrane protein exhibiting a restricted expression pattern including expression in activated B cells. TSPAN33 is a member of the tetraspanin family. TSPAN33 is not expressed in resting B cells, but is strongly induced in primary human B cells following activation. Human 2E2 cells, a Burkitt's lymphoma-derived B cell model of activation and differentiation, also upregulate TSPAN33 upon activation. TSPAN33 is expressed in several lymphomas including Hodgkin's and Diffuse large B cell lymphoma. TSPAN33 is also expressed in some autoimmune diseases where B cells participate in the pathology, including rheumatoid arthritis patients, systemic lupus erythematosus (SLE), and in spleen B cells from MRL/Fas(lpr/lpr) mice (a mouse model of SLE). We conclude that TSPAN33 may be used as a diagnostic biomarker or as a target for therapeutic antibodies for treatment of certain B cell lymphomas or autoimmune diseases.

[National consensus of diagnosis and treatment of non-small cell lung cancer]. / Consenso nacional de diagnóstico y tratamiento del cáncer de pulmón de células no pequeñas.

Mexican specialists in oncology, oncologic surgery, thoracic surgery, pneumology, pathology, molecular biology, anesthesiology, algology, psychology, nutrition, and rehabilitation (all of them experts in lung cancer treatment) in order to develop the National Consensus on Lung Cancer. The consensus has been developed as an answer to the need of updated Mexican guidelines for the optimal treatment of the disease, as well as to the requirements that such guidelines be established by multidisciplinary panel, depicting the current attention given to cancer lung cases in Mexico. Thus, this paper analyses the epidemiological review, screening, diagnosis, staging, pathology, translational medicine, and the suitable therapies for early, locally advanced, and metastatic disease in the first, second, and third lines of management, as well as rehabilitation and palliative measures.

[The imprint cytology: a tool diagnosis in the operating room]. / Impronta citológica: herramienta en el diagnóstico transoperatorio.

BACKGROUND: since 1929, the imprint cytology has a great value in the transoperatory as a diagnostic tool and in some cases as an alternate method. METHODS: during two years period, 416 transoperatory specimens and 384 frozen sections were performed in the Pathology and Cytopathology Department of the University Hospital, "Dr. José E. Gonzalez." Diagnoses were recorded and compared both methods with the final diagnosis given at definitive histological sections. The results were evaluated and p statistics were performed. RESULTS: nine of 416 patients (2.2 %) were incorrectly diagnosed by cytology, and 8 of 384 (2.1 %) by frozen section. The diagnostic accuracy for the imprint cytology was 97.8 % and 97.9 % for frozen section. Six of the 416 cases (1.4 %) were misdiagnosed by imprints and frozen sections; the percentage success was 98.5 % using both methods together. The p was statistically significant (0.0005). CONCLUSIONS: the transoperatory cytology is a fast, easy and inexpensive. It provides morphological detail on intact cells and without the freezing artifacts, so its use as an adjunct to the frozen method is of great value.

TLE1 is expressed in the majority of primary pleuropulmonary synovial sarcomas.

Pleuropulmonary synovial sarcoma (PPSS) is a rare entity, similar to synovial sarcoma of soft tissue (STSS). There are 120 published cases of PPSS, but no studies have explored the expression of TLE1. In soft tissues, it has been proven a useful marker, but in tumors of other sites, its expression has not been explored. The main objective was to study the expression and diagnostic sensitivity and specificity of TLE1 in a group of PPSS, of which the diagnosis was corroborated by fluorescence in situ hybridization confirming t(X;18) in a tissue microarray. Immunohistochemistry including TLE1, vimentin, CD99, CD56, bcl-2, AE1-AE3, EMA, CD34, CK7, CK19, calponin, and S-100 was performed on all PPSS and on 25 control cases (five carcinomas, ten mesotheliomas, and ten thoracic sarcomas). TLE1 was positive in 11 cases (73.3%); bcl-2 and vimentin in 100%; calponin and CD56 in 26.6%; CD99, CK AE1-AE3, CK19, CK7, and EMA in 80%; and S100 negative in all. The only biphasic PPSS was positive for epithelial markers only in the epithelial component. TLE1 was negative in all control cases. TLE1 is expressed in 73% of PPSS, a value inferior to that reported in STSS, but is highly specific for PPSS. TLE1 may therefore be of value in the differential diagnosis of PPSS, but should be used in a panel of antibodies.

Analysis of DNA mismatch repair proteins expression and BRAF V600E mutation in a subset of early- and late-onset colorectal carcinoma patients in Mexico.

BACKGROUND AND AIMS: A third of colorectal carcinomas (CRC) affect patients <50 years of age. Fifteen percent of CRC cases with microsatellite instability are due to inherited germ-line mutations in DNA mismatch repair genes. The rest have an epigenetic hypermethylation of the MLH1 promoter in whom the BRAF V600E mutation is a common hallmark. Immunohistochemistry helps to classify colorectal cancers with 100% specificity and 92% sensitivity. We undertook this study to determine if age is a risk factor for defective MMR protein expression and BRAF mutations in our population and to compare these results with the histopathological tumor features. METHODS: Immunohistochemistry for MLH1 and MSH2 and RT-PCR BRAF V600E mutation was performed on tissue specimens from 57 patients <50 years of age. Data on age, gender, tumor location, histology, depth of infiltration, and the presence of metastatic lymph nodes were collected. Forty eight patients >50 years of age were used as a control group. A statistical analysis using ANOVA, χ(2), and Spearman's rho test were performed. RESULTS: Absent MMR protein expression was more prevalent in patients <50 years of age. No BRAF V600E mutations were detected in either group. Medullary and mucinous types were more prevalent among young patients, whereas intestinal type was more frequent in older patients (p = 0.0008). No differences were found regarding clinicopathological stages between groups. CONCLUSIONS: We found an association between young age and defective MMR expression. No V600E BRAF mutations were detected in either group.

Prevalence of eosinophilic esophagitis in patients with refractory gastroesophageal reflux disease symptoms: A prospective study.

BACKGROUND: Eosinophilic esophagitis (EoE) is not routinely considered in the differential diagnosis of refractory gastroesophageal reflux disease (GERD). AIMS: To prospectively evaluate the prevalence of EoE and describe the clinical features and predictors of EoE in patients with refractory symptoms of GERD. METHODS: Esophageal biopsies were obtained in patients with symptoms of GERD refractory to 8 weeks of conventional antisecretory therapy. Diagnosis of EoE was defined as at least 20 eosinophils × high power field and clinical unresponsiveness to proton pump inhibitors. Clinical and manometric features were compared. Independent risk factors predicting EoE were identified. RESULTS: Six out of 150 included patients (4%) met the diagnostic criteria for EoE. Patients with EoE were significantly younger, had significantly more dysphagia, atopy, ineffective esophageal peristalsis, esophageal rings and esophageal strictures than patients without EoE. Independent predictors of EoE were: age under 45 years (OR 4.8, 95% CI 2.4-8.6), dysphagia (OR 12.2, 95% CI 4.3-19.4), and atopy (OR 3.4, 95% CI 1.5-7.4). CONCLUSIONS: EoE is an uncommon condition (4%) in patients with refractory symptoms of GERD. Age under 45 years, atopy or dysphagia may warrant suspicion of EoE in this subset of patients.