Myoepithelial Markers Research Articles

Abstract 5682: Accelerated biological age is a driver of cancer susceptibility in genetic high risk breast tissue

Abstract During aging in the human mammary gland, luminal epithelial cells lose lineage fidelity by expressing markers normally expressed in myoepithelial cells. We hypothesize that loss of lineage fidelity is a general manifestation of epithelia that are susceptible to cancer initiation. We show that histologically normal breast tissue from younger women who are susceptible to breast cancer because they harbor a germline mutation in BRCA1, BRCA2, or PALB2 genes, exhibit hallmarks of accelerated aging. These include proportionately increased luminal epithelial cells that acquired myoepithelial markers, decreased proportions of myoepithelial cells, and a basal differentiation bias or failure of differentiation of cKit+ progenitors. High-risk luminal and myoepithelial cells are transcriptionally enriched for genes of the opposite lineage, inflammatory, and cancer-related pathways. Genetically high risk luminal epithelial cells also show evidence of accelerated age, by as much as four decades compared to their chronological age, using a breast specific biological clock comprised of measurements of methylation and expression of the luminal-specific ELF5 transcription factor. We have identified breast aging hallmarks that reflect a convergent biology of cancer susceptibility, regardless of the specific underlying genetic or age-dependent risk, or the associated breast cancer subtype. Citation Format: Masaru Miyano, Sundus Shalabi, Rosalyn W. Sayaman, Martha Stampfer, Victoria E. Seewaldt, Mark A. LaBarge. Accelerated biological age is a driver of cancer susceptibility in genetic high risk breast tissue [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5682.

Clinicopathological features of clear cell carcinoma of salivary gland in the head and neck

Objective: To investigate the clinical, histologic, immunohistochemical (IHC) and molecular genetic features of clear cell carcinoma (CCC) of salivary gland in the head and neck regions. Methods: Seven cases of CCC diagnosed in the Department of Pathology, the First Affiliated Hospital of Nanjing Medical University from 2018 to 2021 were included. The clinical and pathologic data, HE sections and IHC staining were reviewed, and EWSR1 gene translocation was detected by fluorescence in situ hybridization (FISH). The relevant literature was also reviewed. Results: There were five males and two females, with an age range of 32 to 71 years (mean 50 years). The tumors were located in the palate, base of tongue, subglottic, right submaxillary and nasopharynx. Histologically the tumors were composed of sheets, nests, and trabecular of large, monomorphic cells which possessed abundant clear and eosinophilic cytoplasm. The stroma was characterized by abundant hyalinized fibrous strands admixed with cellular fibrous (desmoplastic) tissue. The tumor growth was infiltrative. IHC staining revealed positivity for CKpan and squamous cell immunophenotypic markers (CK5/6, p63 and p40), but negativity for myoepithelial markers (SMA, calponin, GFAP and CD10). The EWSR1 gene translocation was detected by FISH. The prognosis was excellent, with the follow-up periods ranging from 8 months to 33 months. During this period, six patients survived without tumor, only one patient with cervical lymph node metastasis. Conclusions: CCC of salivary gland is rare and needs to be differentiated from various other types of tumors containing clear cells. Awareness of the histopathologic characteristics, and combined with IHC and molecular genetic examination can avoid misdiagnosis. The biological behavior of the tumor is indolent with a good overall prognosis.

Single-cell immune mapping of adenoid cystic carcinoma (ACC) reveals potential therapeutic targets for the aggressive solid subtype.

6090 Background: ACC is a common salivary gland malignancy for which there is no FDA approved therapies. Despite a quiet genome, ACC has significant tumoral heterogeneity, which may facilitate the metastatic relapse. Studies focusing on the deep profile of ACC tumor microenvironment (TME) are lacking. Here we explored the TME of ACC using imaging mass cytometry (IMC) and assessed TME attributes and its association with histology and clinical outcomes. Methods: Two tissue microarrays from 62 ACC patients (pts) were built and stained with 37 metal-tagged markers. IMC was performed with the Fluidigm Helios CyTOF instrument utilizing the Hyperion Imaging System Laser ablation. Tissue and cell segmentation and multiplex imaging analysis were performed with Visiopharm software using pre-trained artificial intelligence algorithms. Comparison of cell types and markers densities among histology sub-groups were analyzed with Wilcoxon signed-rank test and its association with overall survival (OS) with log-rank and Cox Proportional Hazards. Results: Of 62 pts, 37% (23/62) had solid histology, 19% (12/62) were metastatic at diagnosis, and 55% (30/54) had disease recurrence during follow-up. With a median follow-up of 7.9 y, the median OS was 9.3y (CI 95%, 7.8-NR). Pts with solid subtype had poorer OS than non-solid histology (5.2 vs 14.6 y, p = 0.004). The IMC final dataset comprised 507,524 single-cells. No significant differences were found in cell subpopulations density between solid and non-solid histology. The most represented cell population in the stroma were macrophages, followed by CD8+ T cells, and fibroblasts. A higher percentage of M2-macrophage was associated with poor survival (p = 0.001), whereas, a higher percentage of M1-macrophage (M1:M2 ratio) was associated with better prognosis. No other immune cell type, fibroblasts or immune cell functional markers (TIGIT, TIM3, granzyme B, and PD-L1) correlated with survival. Regarding tumor markers, a higher expression of BCL-2, B7-H4, and Ki67 in the tumor cells were associated with worst survival; and remained statistically associated after adjustment for histology and staging (all p < 0.001). Solid histology had a significantly higher density of tumor cells expressing B7-H4, BCL-2, and Ki67 compared to cribriform and tubular histology. A higher expression of myoepithelial marker (p63+) were associated with a better survival when compared with tumors with low p63 expression. Conclusions: ACC’s TME is composed mainly of macrophages. Despite having no significant differences in cellular composition, a higher density of tumor cells expressing BCL-2, B7-H4 and Ki67 were found in the solid histology and these markers were independent predictors of poor prognosis. The overexpression of BCL-2 and B7-H4 in the solid histology provides a scientific rationale for BCL-2 and/or B7-H4 targeting for the most aggressive ACC.

Regulation of myoepithelial differentiation.

The salivary gland can be permanently impaired by radiation treatment for head and neck cancers. Efforts at tissue regeneration have focused on saliva-producing acinar cells. However, myoepithelial cells are also critical to gland function, but mechanisms that regulate their differentiation are poorly defined. To study myoepithelial differentiation, we employed mSG-PAC1 murine salivary gland epithelial cells. We demonstrate that mSG-PAC1 spheroids exhibit phenotypic plasticity between pro-acinar and myoepithelial cell fates. Increased expression of pro-acinar/acinar or myoepithelial RNAs was identified from spheroids cultured under different media conditions by microarray followed by gene-set enrichment analysis. Spheroids cultured with different medium components expressed proteins typical of either acinar or myoepithelial cells, as detected by immunocytochemistry. We demonstrate that the pattern of TAZ expression in the epithelial compartment of the differentiating murine salivary gland correlates with the expression of the myoepithelial marker alpha-SMA, as is the case for TAZ expression in mSG-PAC1 spheroids. Our analysis also indicates that YAP/TAZ target genes are upregulated together with myoepithelial markers. Importantly, siRNA targeting of TAZ expression in mSG-PAC1 spheroids diminished the expression of myoepithelial markers. Our results in this in vitro cell model implicate TAZ signaling in myoepithelial differentiation.

Prognostic value of integrin αV expression and localization pattern in invasive breast carcinomas

Invasion of surrounding stroma is an early event in breast cancer metastatic progression, and involves loss of cell polarity, loss of myoepithelial layer, epithelial-mesenchymal transition (EMT) and remodeling of the extracellular matrix (ECM). Integrins are transmembrane receptors responsible for cell-ECM binding, which triggers signals that regulate many aspects of cell behavior and fate. Changes in the expression, localization and pairing of integrins contribute for abnormal responses found in transformed epithelia. We analyzed 345 human breast cancer samples in tissue microarrays (TMA) from cases diagnosed with invasive breast carcinoma to assess the expression and localization pattern of integrin αV and correlation with clinical parameters. Patients with lower levels of integrin αV staining showed reduced cancer specific survival. A subset of cases presented a peripheral staining of integrin αV surrounding tumor cell clusters, possibly matching the remaining myoepithelial layer. Indeed, the majority of ductal carcinoma in situ (DCIS) components found in the TMA presented integrin αV at their periphery, whereas this pattern was mostly lost in invasive components, even in the same sample. The lack of peripheral integrin αV correlated with decreased cancer specific survival. In addition, we observed that the presence of integrin αV in the stroma was an indicative of poor survival and metastatic disease. Consistently, by interrogating publicly available datasets we found that, although patients with higher mRNA levels of integrin αV had increased risk of developing metastasis, high co-expression of integrin αV and a myoepithelial cell marker (MYH11) mRNA levels correlated with better clinical outcomes. Finally, a 3D cell culture model of non-malignant and malignant cells reproduced the integrin αV pattern seen in patient samples. Taken together, our data indicate that both the expression levels of integrin αV and its tissue localization in primary tumors have prognostic value, and thus, could be used to help predict patients at higher risk of developing metastasis.

Establishment and characterization of equine mammary organoids using a method translatable to other non-traditional model species.

Mammary organoid (MaO) models are only available for a few traditional model organisms, limiting our ability to investigate mammary gland development and cancer across mammals. This study established equine mammary organoids (EqMaOs) from cryopreserved mammary tissue, in which mammary tissue fragments were isolated and embedded into a 3D matrix to produce EqMaOs. We evaluated viability, proliferation and budding capacity of EqMaOs at different time points during culture, showing that although the number of proliferative cells decreased over time, viability was maintained and budding increased. We further characterized EqMaOs based on expression of stem cell, myoepithelial and luminal markers, and found that EqMaOs expressed these markers throughout culture and that a bilayered structure as seen in vivo was recapitulated. We used the milk-stimulating hormone prolactin to induce milk production, which was verified by the upregulation of milk proteins, most notably β-casein. Additionally, we showed that our method is also applicable to additional non-traditional mammalian species, particularly domesticated animals such as cats, pigs and rabbits. Collectively, MaO models across species will be a useful tool for comparative developmental and cancer studies.

Study on the Clinicopathological Characteristics of Adenoid Cystic Carcinoma of the Breast

Adenoid cystic carcinoma of the breast (BACC) is a rare type of invasive ductal breast cancer. The present study aimed to determine the clinicopathological characteristics of BACC in order to determine markers for accurate diagnosis and prognosis. A retrospective analysis of clinicopathological characteristics was conducted in 28 cases of BACC and 30 cases of nonspecific invasive breast cancer which served as the controls. All BACC patients were female, aged from 42 to 63 years. No lymph node metastasis, as well as nerve and lymphovascular invasion, was found in the BACC group. Twenty BACC cases showed classical tubular or cribriform structure, while eight other cases showed tumors of solid variant with obvious atypical cells that were proliferating with frequent mitosis. Epithelial and myoepithelial markers such as cytokeratin 7, CD117, epidermal growth factor receptor, and P63 were expressed in BACC cases. MYB was expressed in 26 BACC cases. Local recurrence happened in two BACC cases who were tested positive for nuclear protein 1 (NUPR1) during a 10 – 84-month follow-up. The expression of MYB and NUPR1 had a significant difference between the two groups (P < 0.001). In conclusion, the present study showed that BACC is associated with low invasive characteristics and relatively inert biological behavior on the account of the vast majority of BACC cases which were tested negative for NUPR1. The study also implied that NUPR1 is an indicator of poor prognosis of the tumor. Meanwhile, our study also corroborated the significance of MYB expression for its discriminatory role in BACC diagnosis and differential diagnosis. Therefore, these cases are generally not advocated for chemotherapy, but rather, they are expected to be treated with MYB-targeted therapy.

Myoepithelial progenitors as founder cells of hyperplastic human breast lesions upon PIK3CA transformation

The myoepithelial (MEP) lineage of human breast comprises bipotent and multipotent progenitors in ducts and terminal duct lobular units (TDLUs). We here assess whether this heterogeneity impacts on oncogenic PIK3CA transformation. Single cell RNA sequencing (scRNA-seq) and multicolor imaging reveal that terminal ducts represent the most enriched source of cells with ductal MEP markers including α-smooth muscle actin (α-SMA), keratin K14, K17 and CD200. Furthermore, we find neighboring CD200high and CD200low progenitors within terminal ducts. When sorted and kept in ground state conditions, their CD200low and CD200high phenotypes are preserved. Upon differentiation, progenitors remain multipotent and bipotent, respectively. Immortalized progenitors are transduced with mutant PIK3CA on an shp53 background. Upon transplantation, CD200low MEP progenitors distinguish from CD200high by the formation of multilayered structures with a hyperplastic inner layer of luminal epithelial cells. We suggest a model with spatially distributed MEP progenitors as founder cells of biphasic breast lesions with implications for early detection and prevention strategies.

Assessment of MEF2C as a novel myoepithelial marker using normal salivary gland and pleomorphic adenoma: An immunohistochemical study

The myoepithelium of the salivary gland demonstrates smooth muscle properties, and the myoepithelium-rich pleomorphic adenomas (PA) exhibit various cytological guises and frequently produce chondroid tissues. We recently reported that gene expression of myocyte enhancer factor 2 C (MEF2C) was up-regulated in myoepithelial cell lines established from mouse salivary glands. This transcription factor is known to regulate the development of smooth muscle cells and chondrocytes. These findings have led us to postulate that MEF2C may be a new marker of the myoepithelium and thus be of help for exploring myoepithelial participation in PA. The immunoreactivity of MEF2C was semi-quantitatively analyzed in normal salivary glands and in different types of cell in PA. The pattern of staining was also compared with that of α-smooth muscle actin (αSMA) and calponin. In the parenchyma of mouse and human submandibular glands, MEF2C expression was exclusive to the nuclei of myoepithelial cells. In the neoplastic myoepithelium of PA, epithelioid and stellate cells were consistently positive, but spindle and plasmacytoid cells exhibited selective staining. Although variability/loss of expression was evident, αSMA tended to show limited expression, whereas calponin tended to show extensive expression. Intense and uniform immunoreactivity for MEF2C was observed in lacunar cells in chondroid areas of PA. This is the first reported study to have demonstrated MEF2C immunoexpression in normal and neoplastic myoepithelial cells. Among the heterogeneously differentiated elements, MEF2C may be useful to define the myoepithelial/mesenchymal phenotypes of PA cells. Along with other relevant immunohistochemical markers, it may become another standard.

Encapsulation of Primary Salivary Gland Acinar Cell Clusters and Intercalated Ducts (AIDUCs) within Matrix Metalloproteinase (MMP)-Degradable Hydrogels to Maintain Tissue Structure and Function.

Progress in the development of salivary gland regenerative strategies is limited by poor maintenance of the secretory function of salivary gland cells (SGCs) in vitro. To reduce the precipitous loss of secretory function, a modified approach to isolate intact acinar cell clusters and intercalated ducts (AIDUCs), rather than commonly used single cell suspension, is investigated. This isolation approach yields AIDUCs that maintain many of the cell-cell and cell-matrix interactions of intact glands. Encapsulation of AIDUCs in matrix metalloproteinase (MMP)-degradable PEG hydrogels promotes self-assembly into salivary gland mimetics (SGm) with acinar-like structure. Expression of Mist1, a transcription factor associated with secretory function, is detectable throughout the in vitro culture period up to 14 days. Immunohistochemistry also confirms expression of acinar cell markers (NKCC1, PIP and AQP5), duct cell markers (K7 and K5), and myoepithelial cell markers (SMA). Robust carbachol and ATP-stimulated calcium flux is observed within the SGm for up to 14 days after encapsulation, indicating that secretory function is maintained. Though some acinar-to-ductal metaplasia is observed within SGm, it is reduced compared to previous reports. In conclusion, cell-cell interactions maintained within AIDUCs together with the hydrogel microenvironment may be a promising platform for salivary gland regenerative strategies.

The role of p63 Myoepithelial cell marker in papillary lesions of the breast

Background: To diagnose various histological types of papillary lesions of the breast according to the newer WHO classification and to study the expression of myoepithelial cell marker p63 in various papillary lesions. Material and Methods: The study was done on 21 patients with breast lesions between Jan 2015 to June 2016. Breast biopsies (incisional as well as excisional) were retrieved from the histopathology section of the department. Result: P63 showed a nuclear positivity in myoepithelial cells. It was retained in the benign papillary lesions with some exceptions and was almost completely lost in malignant papillary neoplasms Conclusion: P63 can be used to observe the characteristic pattern of nuclear staining and delineate the myoepithelial layer wherever needed.

Papillary Lesions of Breast- A Retrospective Analysis of Cytomorphological Features with Histopathology Concordance

Introduction: Papillary lesions of the breast include a spectrum of entities ranging from benign papilloma to malignant papillary carcinoma. The overlapping morphological features in benign and malignant lesions make their accurate sub categorization difficult. Definitive surgical management decisions on papillary lesions of breast based on fine needle aspiration cytology report alone is a matter of concern. Aim: To evaluate the cytomorphological features of papillary lesions of breast and its concordance with histopathology. Materials and Methods: This retrospective study was conducted in Department of Pathology at Regional Cancer Centre, Thiruvananthapuram, Kerala, India (tertiary cancer centre) from January 2017 to June 2017. Total 28 cases diagnosed as papillary lesions/neoplasm on nipple discharge/fine needle aspiration cytology (FNAC) from January 2014 to December 2016 were reviewed and concordance with histopathology where ever available was analysed. Cytomorphological features that were analysed included cellularity, complex folded and branching epithelial sheets, stromal bare nuclei, cyst macrophages, single cells and atypia. Results: Total 28 cases of papillary lesions diagnosed by cytology were identified with mean age of 51 years. Out of 28, 22 cases had histopathology concordance. Most common diagnosis in cytology was papillary neoplasm, accurate categorization into benign or malignant could not be done in cytology in most of the cases. Most common diagnosis in histopathology was carcinoma, in-situ and invasive. Of total 22 cases,16 cases showed true papillae. Majority of the cytomorphological features assessed were statistically insignificant in differentiating benign and malignant lesions. Fifteen cases out of the total 22 cases turned out to be malignant in final histopathology. Out of the total 22 cases wherein histopathology correlation was available, cytology could give a conclusive diagnosis of malignancy in two cases and could give a suggestion of malignancy in seven cases. Out of these nine cases where cytology favoured malignancy, one case turned out to be benign in histopathology while the rest eight cases were malignant. In five cases cytology gave benign diagnosis, one of these turned out to be malignant in histopathology, rest four cases histopathological diagnosis was in concordance with cytology. In eight cases cytology gave an equivocal diagnosis of papillary neoplasm, where further categorisation into benign and malignant category was not possible. Out of these equivocal cases, six turned out to be malignant in histopathology and two were benign. Conclusion: Cytomorphological features of papillary lesions of the breast are not unique and are inadequate for consistent categorization into benign and malignant lesions. Excision biopsy with adequate sampling and immunostaining with myoepithelial markers and oestrogen and progesterone receptors (ER and PR) are essential for accurate categorization of papillary neoplasms of breast.

Avoiding "False Positive" and "False Negative" Immunohistochemical Results in Breast Pathology.

Immunohistochemistry (IHC) plays an important role in the evaluation of breast pathology specimens to provide both diagnostic and prognostic/therapeutic information. Although most IHCs used in breast pathology can be easily interpreted, pitfalls do exist, especially in some uncommon scenarios. This review intends to focus on the challenging areas such as the interpretation of myoepithelial cell markers in differentiating benign proliferation and in situ carcinoma from invasive carcinoma, lobular cell markers in differentiating lobular from ductal carcinoma, cytokeratin and other markers in diagnosing metaplastic carcinoma, and breast tissue origin markers in diagnosing breast primary carcinoma. The challenges in interpreting prognostic and predictive markers will be also discussed.

Expression of Ki-67, P63, P40, and alpha-smooth muscle actin in salivary gland carcinomas with or without myoepithelial differentiation

Background: Myoepithelial cells are involved in the development of salivary glands. Many studies propose that these cells can prevent cell proliferation. Aim: This study aimed to investigate the expression of Ki-67, P63, P40, and alpha-smooth muscle actin (α-SMA) in salivary gland carcinomas with or without myoepithelial differentiation. Methods: A panel of myoepithelial markers including P63, P40, α-SMA, and Ki-67 were used for immunohistochemical study in 67 salivary gland carcinomas (33 with and 34 without myoepithelial differentiation). The percentage of positive cells was calculated (in high-power field) from a minimum of 1000 neoplastic cells. SPSS software (version 21) was used. Results: There was no statistically significant difference between Ki-67 expression and the presence or absence of myoepithelial cells (P = 0.6), but Ki-67 expression was related to the age (P = 0.032) and location of carcinomas (P = 0.001). All carcinomas with myoepithelial differentiation exhibited consistent P63+/P40+ staining, whereas polymorphous adenocarcinomas showed P63+/P40− immunophenotype. The expression of Ki-67 in adenoid cystic carcinomas was higher than mucoepidermoid carcinomas (P = 0.020) and polymorphous adenocarcinomas (P = 0.002). Conclusion: In the present study, although the decrease in the number of myoepithelial cells was associated with increased proliferation in adenoid cystic carcinomas, no such relationship was found in the overall assessment between the two groups. This can be justified by the fact that the clinical behavior of salivary carcinomas and their cell proliferation may be affected by factors other than the presence of myoepithelial cells or lack thereof. Ki-67 and P63/P40 expressions may be useful to differentiate adenoid cystic carcinomas from polymorphous adenocarcinomas in small biopsies.

Induction of salivary gland-like cells from epithelial tissues transdifferentiated from mouse embryonic fibroblasts

Salivary gland hypofunction due to radiation therapy for head and neck cancer or Sjögren syndrome may cause various oral diseases, which can lead to a decline in the quality of life. Cell therapy using salivary gland stem cells is a promising method for restoring hypofunction. Herein, we show that salivary gland-like cells can be induced from epithelial tissues that were transdifferentiated from mouse embryonic fibroblasts (MEFs). We introduced four genes, Dnp63a, Tfap2a, Grhl2, and Myc (PTMG) that are known to transdifferentiate fibroblasts into oral mucosa-like epithelium in vivo into MEFs. MEFs overexpressing these genes showed epithelial cell characteristics, such as cobblestone appearance and E-cadherin positivity, and formed oral epithelial-like tissue under air–liquid interface culture conditions. The epithelial sheet detached from the culture dish was infected with adenoviruses encoding Sox9 and Foxc1, which we previously identified as essential factors to induce salivary gland formation. The cells detached from the cell sheet formed spheres 10 days after infection and showed a branching morphology. The spheres expressed genes encoding basal/myoepithelial markers, cytokeratin 5, cytokeratin 14, acinar cell marker, aquaporin 5, and the myoepithelial marker α-smooth muscle actin. The dissociated cells of these primary spheres had the ability to form secondary spheres. Taken together, our results provide a new strategy for cell therapy of salivary glands and hold implications in treating patients with dry mouth.

A Diagnostic Pitfall in the Evaluation of CD138-Positive Plasmacytoid Cells in a Fine Needle Aspiration Biopsy

Abstract Introduction/Objective The identification of plasmacytoid cells on rapid assessment leads to a wide range of differential diagnoses. Methods/Case Report We present a 51-year-old female with a parotid mass and cervical lymphadenopathy. The fine needle aspiration biopsy of the lymph node showed clusters of plasmacytoid cells. Flow cytometric studies showed cells positive for CD19, CD45, CD138 and kappa, but negative for CD38 and lambda. The kappa to lambda ratio was greater than 100. Histological sections showed plasmacytoid cells that were positive for AE1/AE3, S100, and SOX10, weakly positive for CK7 and GATA3, but negative for CD79a, CD45, EMA, p40, p63, and pan-melanoma markers. Kappa and lambda had a 1:1 ratio. Due to the discrepancy between the flow cytometric results and the immunohistochemistry, excision was recommended. The subsequent excision specimen showed classic morphology for myoepithelial carcinoma, plasmacytoid variant. Results (if a Case Study enter NA) NA Conclusion Myoepithelial carcinomas of the salivary glands are rare neoplasms, and they have various morphologies. The plasmacytoid variant can pose as a diagnostic pitfall. In fine needle aspiration biopsies, carcinoma cells with plasmacytoid morphology can be confused with a plasma cell neoplasm. CD138 is nonspecific marker, and it can be expressed in plasma cells as well as carcinomas. To further complicate matters, pancytokeratin and SOX10 can aberrantly expressed in some plasma cell myelomas. Flow cytometry studies is a valuable tool to define various cell types. However, it can be misleading if it is used as a sole source for interpreting plasmacytoid cells. Epithelial and myoepithelial neoplasms should be considered as differential diagnoses when CD138-positive plasmacytoid cells are encountered. Extended immunohistochemistry panel including multiple epithelial and myoepithelial markers play pivotal role in settling the diagnosis.

Evidence for accelerated aging in mammary epithelia of women carrying germline BRCA1 or BRCA2 mutations

During aging in the human mammary gland, luminal epithelial cells lose lineage fidelity by expressing markers normally expressed in myoepithelial cells. We hypothesize that loss of lineage fidelity is a general manifestation of epithelia that are susceptible to cancer initiation. In the present study, we show that histologically normal breast tissue from younger women who are susceptible to breast cancer, as a result of harboring a germline mutation in BRCA1, BRCA2 or PALB2 genes, exhibits hallmarks of accelerated aging. These include proportionately increased luminal epithelial cells that acquired myoepithelial markers, decreased proportions of myoepithelial cells and a basal differentiation bias or failure of differentiation of cKit+ progenitors. High-risk luminal and myoepithelial cells are transcriptionally enriched for genes of the opposite lineage, inflammatory- and cancer-related pathways. We have identified breast-aging hallmarks that reflect a convergent biology of cancer susceptibility, regardless of the specific underlying genetic or age-dependent risk or the associated breast cancer subtype.

Dec1 deficiency restores the age-related dysfunctions of submandibular glands.

Age-related organ and tissue-specific cell kinetic and morphological alterations are associated with the incidence of numerous diseases in old age. Salivary dysfunction frequently appears in a wide range of older people and thus is a physiological and biological aspect of aging. The transcription factor Dec1 (differentiated embryo chondrocyte expressed gene 1) is essential for the regulation of cellular senescence. Here, we explored the morphological and physiological abnormalities and the microRNA (miRNA) expression profiles in the submandibular glands (SMGs) of young (3-month-old) and of aged (24-month-old) wild-type (WT) and Dec1KO mice. Hematoxylin-eosin (H-E) staining, Masson's Trichrome staining, immunohistochemistry, immunofluorescence, and quantitative real time PCR were employed. MicroRNA (miRNA) expression profiles were examined using an Agilent system with a Mouse 8x60K array. Immunohistochemical analysis revealed an increased oxidative stress response (8-OHdG), increased expression levels of type I collagen in the fibrotic tissues with substantial amounts of fibroblasts and collagen fibers, the presence of CCl-22-positive lymphocytes infiltrating the SMGs of aged WT mice and a subsequently enhanced expression of fibrosis-associated gene (MMP-2) in the aged SMGs. The water channel protein aquaporin-5 (AQP5) was expressed in the basal cytoplasmic regions of acini in young SMGs but showed a decreased expression in aged SMGs. Myoepithelial cell markers (p63 immunoreactivity and a-SMA immunofluorescence staining) were also decreased in aged SMGs. Quantitative real-time PCR revealed decreased mRNA expression levels of AQP5 and increased mRNA expression levels of Dec1 in aged WT mice. All those characteristics were attenuated in aged Dec1KO mice. There were no apparent differences between young WT and Dec1KO mice. Of the miRNAs analyzed, miR-181c-5p, miR-141-3p, miR-374c-5p and miR-466i-3p are proposed regulatory targets of Dec1 and AQP5 genes that are involved in SMG dysfunction in aged mice. We suggest that a Dec1 deficiency might alleviate the aging-induced hypofunction of SMGs and relevant alterations of Dec1 would be useful to keep SMGs healthy. This study provides clues for determining unique microRNAs concerned with SMG dysfunction. Subsequent activation of such diversely expressed miRNAs be of great value in clarifying the nature of age-related alterations in SMGs.

Solid Papillary Carcinoma and Encapsulated Papillary Carcinoma of the Breast: Clinical-Pathologic Features and Basement Membrane Studies of 50 Cases

Introduction: Solid papillary carcinoma (SPC) and encapsulated papillary carcinoma (EPC) of the breast are usually considered in situ lesions due to favorable prognosis, despite the variable presence of myoepithelial cells. We aimed to describe clinical-pathologic features including basement membrane (BM) studies in these tumors. Methods: Patients diagnosed with SPC and EPC in 2000–2019 were retrospectively identified. Microscopic slides and clinical history were reviewed. Immunohistochemical stains for BM and myoepithelial markers were performed. Results: Of 23 SPCs and 27 EPCs, there were 5/23 (21.7%) pure SPCs and 9/27 (33.3%) pure EPCs, while 4/23 (17.4%) and 12/27 (44.5%) were associated with ductal carcinoma in situ (DCIS), and 6/23 (26.1%) and 6/27 (22.2%) with invasive carcinoma, respectively; 8/23 (34.8%) SPCs were considered invasive. The median tumor size was 1.7 cm (range 0.1–16). All tumors were positive for hormone receptors and negative for HER2. Myoepithelial cells were absent in 20 tumors (40%) and focally present in 30 (60%). Collagen IV and laminin were negative in most invasive lesions, but they were expressed in 21/21 (100%) and 18/21 (85.7%) of EPCs without invasion, and 16/17 (94.1%) and 10/17 (58.8%) SPCs, including invasive SPCs, respectively. Lymph node involvement was identified in 3/26 (11.5%) patients, including micrometastasis in 1 EPC associated with DCIS, macrometastasis in 1 EPC associated with invasive carcinoma, and isolated tumor cells in 1 invasive SPC. Of 31 patients with outcome data (median follow-up 35 months, range 1–85), 2 (6.5%; 1 SPC, 1 EPC) developed local recurrence, both associated with invasive carcinoma. No distant recurrences or deaths were observed. Conclusions: Our study confirms favorable prognosis of SPCs and EPCs, with 2 local recurrences occurring in the presence of invasion. SPCs are more commonly associated with invasive carcinoma or considered invasive compared to EPCs (60.9 vs. 22.2%). The presence of BM material and lack of lymph node involvement in most cases indicates that the majority of these tumors may represent in situ lesions; however, some may behave as low-grade invasive malignancy with metastatic potential even in the absence of conventional invasion.

SALIVARY MICROSECRETORY ADENOCARCINOMA - CASE REPORT OF A RECENTLY DESCRIBED ENTITY

<h3>Clinical Presentation</h3> A 35-year-old female patient presented with a 1.5-cm left hard palate swelling. The incisional biopsy was inconclusive, and imaging suggested a nonaggressive lesion with no evidence of bone invasion. The lesion was excised and sent for histopathologic examination. <h3>Histology</h3> Histologic examination showed a well-defined and unencapsulated multilobular lesion within the connective tissue exhibiting morphological diversity with areas of ductal differentiation, prominent cytoplasmic clearing, and areas with an eosinophilic and epithelioid appearance. In places, cords and trabeculae of tumor cells with a prominent microcystic appearance were seen with surrounding fibromyxoid stroma. Focally, the tumor cells showed a spindled and somewhat infiltrative appearance, but there was no evidence of single-cell filing or perineural or lymphovascular invasion. <h3>Further Investigations</h3> Immunohistochemistry showed diffuse staining for CK7, Cam5.2, and S100 with p63 staining in a significant proportion of the tumor cells. There was no evidence of a biphasic population, and other myoepithelial markers (i.e., calponin and p40) were also negative. Ki67 staining showed a low proliferation index of approximately 5%. Targeted RNA sequencing showed the presence of <i>MEF2C-SS18</i> gene fusion, leading to a definitive diagnosis of salivary microsecretory adenocarcinoma (MA). <h3>Discussion</h3> Salivary MA is a recently described entity characterized by the <i>MEF2C-SS18</i> gene fusion. The differential diagnosis includes an adenocarcinoma not otherwise specified, and the immunohistochemical profile is similar to a polymorphous adenocarcinoma; however, both of these entities lack the characteristic molecular signature. Only 5 cases of MA have been reported to date, with our case adding to the existing literature on this emerging entity.