Canine and feline in situ mammary carcinoma: A comparative review.

Carcinoma in situ of the breast is a well-known entity in humans. In veterinary medicine, particularly in canine and feline mammary literature, there is no agreement whether the term in situ should be used to indicate a specific carcinoma histotype or the noninvasive status of a carcinoma of any histotype. Moreover, in the most recent histologic classification of mammary tumors published by the Davis-Thompson Foundation, it is suggested to abandon the term carcinoma in situ given the lack of standardized criteria defining this entity, replacing it with epitheliosis or ductal/lobular hyperplasia with severe atypia. This publication presents a critical review of the term in situ in human and veterinary medicine considering the evolution of the term over the years and its heterogeneous use by different authors, including variations in immunohistochemical markers for classification. This review aims to point out the lack of uniformity in the nomenclature and classification issues in veterinary medicine regarding the use of the term in situ, laying the ground for a process of standardization in future publications.

Histological and immunohistochemical investigation of canine prostate carcinoma with identification of common intraductal carcinoma component.

A limited number of species, including men and dogs, spontaneously develop prostate cancer (PC). The histological and molecular relevance of canine PC as a model for the disease in men remains controversial. To address this challenge, this study aimed to assess the histomorphology and expression of basal cell, urothelial and neuroendocrine markers [p63, high molecular weight cytokeratin (HMWCK), Uroplakin 3 (UPIII), neuron-specific enolase (NSE)] in canine PC (n = 41). Based on histomorphology, 10/41 (24%), 21/41 (51%) and 9/41 (22%) were classified as adenocarcinoma (AC), urothelial carcinoma (UC), and mixed carcinoma, respectively. Tumour inflammation was common, frequently severe [20/41 (49%)], and associated with neutering (p < .02) and urothelial differentiation (p < .02). Most (36/40, 90%) cancers contained only rare cells with basal cell marker expression or were negative. The expression of UPIII was absent or weak in the majority (33/38, 87%) of tumours, with moderate to strong staining in the remaining cases. NSE expression in PC was rare and limited to 2/14 (14%) cases. Tumour extension into benign ducts and glands was a common finding with presence in 17/39 (44%) of carcinomas with and without urothelial differentiation. In conclusion, we confirm that canine PC is characterized by absent or weak expression of basal cell and urothelial markers. Although rare, NSE expression, potentially indicating neuroendocrine differentiation, is reported for the first time in canine PCa. Intraductal carcinoma of the prostate with concurrent invasive PCa (IDCP-inv) is a frequent, not previously described, finding in dogs with PC.

DNA methylation landscape of triple-negative ductal carcinoma in situ (DCIS) progressing to the invasive stage in canine breast cancer.

Triple-negative breast cancer (TNBC) is a subtype of breast cancer unresponsive to traditional receptor-targeted treatments, leading to a disproportionate number of deaths. Invasive breast cancer is believed to evolve from non-invasive ductal carcinoma in situ (DCIS). Detection of triple-negative DCIS (TN-DCIS) is challenging, therefore strategies to study molecular events governing progression of pre-invasive TN-DCIS to invasive TNBC are needed. Here, we study a canine TN-DCIS progression and investigate the DNA methylation landscape of normal breast tissue, atypical ductal hyperplasia (ADH), DCIS and invasive breast cancer. We report hypo- and hypermethylation of genes within functional categories related to cancer such as transcriptional regulation, apoptosis, signal transduction, and cell migration. DNA methylation changes associated with cancer-related genes become more pronounced at invasive breast cancer stage. Importantly, we identify invasive-only and DCIS-specific DNA methylation alterations that could potentially determine which lesions progress to invasive cancer and which could remain as pre-invasive DCIS. Changes in DNA methylation during TN-DCIS progression in this canine model correspond with gene expression patterns in human breast tissues. This study provides evidence for utilizing methylation status of gene candidates to define late-stage (DCIS and invasive), invasive stage only or DCIS stage only of TN-DCIS progression.

Quantification of EGFR family in canine mammary ductal carcinomas in situ: implications on the histological graduation.

The epithelial growth factor receptors are transmembrane proteins with an important role in the neoplastic progression of tumors, and in this context, DCIS is an important phase in the progression of canine mammary tumors. Studies on the molecular profile and its relationship to a progression of canine mammary tumors are important to improve the treatment of patients and for a better understanding of canine mammary carcinogenesis. The aim of this study was to determine, by immunohistochemistry, the relation between the expression of EGFR, ErbB-2, ErbB-3, and ErbB-4 in 52 canine mammary gland DCIS with high and low histological grade. A positive correlation between histological grade and expression of membrane ErbB-2 and cytoplasmic ErbB-4 was observed. Increased ErbB-4 membrane expression was correlated with increased ErbB-3 expression in low and high-grade DCIS. Our data suggest that increased expression of ErbB-2 and ErbB-4 may be related to more aggressive DCIS and probabily involved with canine mammary neoplastic progression.

Prognostic Significance of Canine Mammary Tumor Histologic Subtypes: An Observational Cohort Study of 229 Cases.

Histopathology is considered the gold standard diagnostic method for canine mammary tumors. In 2011, a new histologic classification for canine mammary tumors was proposed. The present study was a 2-year prospective study that validated the 2011 classification as an independent prognostic indicator with multivariate analysis in a population of 229 female dogs, identifying subtype-specific median survival times (MST) and local recurrence/distant metastasis rates. Dogs with benign tumors and carcinoma arising in benign mixed tumors all had an excellent prognosis. Dogs with complex carcinoma and simple tubular carcinoma also experienced prolonged survival. Those with simple tubulopapillary carcinoma, intraductal papillary carcinoma, and carcinoma and malignant myoepithelioma had a more than 10-fold higher risk of tumor-related death. The prognosis was even worse for adenosquamous carcinoma (MST = 18 months), comedocarcinoma (MST = 14 months), and solid carcinoma (MST = 8 months). The most unfavorable outcome was for anaplastic carcinoma (MST = 3 months) and carcinosarcoma (MST = 3 months), which also had the highest metastatic rates (89% and 100%, respectively). Adenosquamous carcinoma exhibited the highest local recurrence rate (50%). In the same canine population, the tumor diameter was recognized as a strong predictor of local recurrence/distant metastasis and an independent prognosticator of survival in the multivariate analysis. Excision margins were predictive only of local recurrence, whereas lymphatic invasion and histologic grade were predictive of local recurrence/distant metastasis and survival, although only in univariate analyses. In conclusion, this study validated the 2011 classification scheme and provided information to be used in the clinical setting and as the basis for future prognostic studies.

Perinatal Exposure to Bisphenol A or Diethylstilbestrol Increases the Susceptibility to Develop Mammary Gland Lesions After Estrogen Replacement Therapy in Middle-Aged Rats.

The development of the mammary gland is a hormone-regulated event. Several factors can dysregulate its growth and make the gland more susceptible to cellular transformation. Among these factors, perinatal exposure to xenoestrogens and hormone replacement therapy has been associated with increased risk of developing breast cancer. Here, we assessed the effects induced by estrogen replacement therapy (ERT) in ovariectomized (OVX) middle-aged rats and whether perinatal exposure to diethylstilbestrol (DES) or bisphenol A (BPA) modified these effects in the mammary gland. Pregnant rats were orally exposed to vehicle, 5 µg DES/kg/day, or 0.5 or 50 µg BPA/kg/day from gestational day 9 until weaning. Then, 12-month-old offspring were OVX and treated with 17ß-estradiol for 3 months. Morphological changes and the percentage of epithelial cells that proliferated or expressed estrogen receptor alpha (ESR1) and progesterone receptor (PR) were analyzed in mammary gland samples of 15-month-old animals. ERT induced lobuloalveolar hyperplasia and ductal cysts in the mammary gland of middle-aged rats, associated with a higher proliferation index of epithelial cells. Perinatal exposure to DES followed by ERT increased the number of cysts and induced the formation of fibroadenoma and ductal carcinoma in situ, without modifying the expression of ESR1 or PR. Also, after 3 months of ERT, BPA-exposed rats had a higher incidence of ductal hyperplasia and atypical lobular hyperplasia than animals under ERT alone. In conclusion, perinatal exposure to xenoestrogens increases the susceptibility of the mammary gland to develop cysts and hyperplastic lesions when confronted with ERT later in life.

Proposed classification of the feline "complex" mammary tumors as ductal and intraductal papillary mammary tumors.

When compared with the canine species, feline mammary tumors (FMTs) are much less heterogeneous, with a predominance of simple malignant neoplasm. Benign FMTs are rare, and it is unclear if complex and mixed tumors exist in the feline. In this study, we selected for immunohistochemical analyses 12 FMTs that had unusual histologic features. A group of 8 (2 benign and 6 malignant) FMTs showed a biphasic epithelial/myoepithelial population and a very regular cord-like distribution in a "Chinese lettering" pattern, within ectatic ducts. A second group (2 benign and 2 malignant) had an intraductal epithelial papillary growth pattern with a basally located monolayer of myoepithelial cells and a supporting fibrovascular stroma. The myoepithelial component always produced a standard immunohistochemical signature. All malignancies were grade I, and the subjects were all alive at 1 year postdiagnosis. On the basis of their morphology, we propose that they be classified as feline ductal adenoma/carcinoma and feline intraductal papillary adenoma/carcinoma, respectively. They overlap with their canine counterparts and lack the typical myoepithelial differentiation patterns seen in canine complex neoplasms, and therefore, the term complex should be avoided in felines. This study will add new information on FMT classification and be useful for prognostic studies.

Immunohistochemical and molecular analysis of caveolin-1 expression in canine mammary tumors.

Caveolin-1 (Cav-1) is a structural protein present in invaginations of the cell membrane. In human breast cancer, the cav-1 gene is believed to be a tumor suppressor gene associated with inhibition of tumor metastasis. However, little is known about its expression, regulation and function in canine mammary tumors. Expression levels of cav-1 were investigated using real-time PCR and immunohistochemical detection with an anti-human Cav-1 antibody. Gene expression stability of different samples was analyzed using the geNorm software. Mammary tumors from 51 female dogs were compared to normal mammary tissue from 10 female dogs. Malignant mammary cells showed a loss of Cav-1 expression by quantitative RT-PCR and weak Cav-1 staining by immunohistochemistry compared to normal mammary gland tissue. There was a significant relationship between outcome and immunostaining as well as with tumor size, indicating that caveolin subexpression has a positive predictive value and is related to higher survival and smaller tumor size. Our findings indicate that Cav-1 is a potential prognostic marker for canine mammary tumors.

A spontaneously occuring mammary gland ductal carcinoma in situ in a rhesus macaque (Macaca mulatta) and a review of spontaneous mammary gland tumors in rhesus monkeys.

A spontaneous mammary gland ductal carcinoma in situ was diagnosed in a 6-8-year-old female rhesus macaque (Macaca mulatta). To our knowledge, this is only the tenth case of spontaneous mammary gland tumors to be reported in rhesus monkeys. Despite the paucity of case reports, several theories exist to explain the occurrence of mammary tumors. The Mason Pfizer monkey virus, a type D retrovirus similar to the virus that causes simian acquired immunodeficiency syndrome, has been implicated as a possible etiologic agent. Because this virus has been isolated from normal primate mammary tissue, it is unlikely to be the sole etiologic agent. Other theories include the tumorogenic effects that androgens, growth hormones, irradiation, and aging have on the mammary gland.

Preliminary studies on congenital hypothyroidism in a family of Abyssinian cats.

Congenital hypothyroidism was diagnosed in related Abyssinian cats. The disease appeared to be inherited as an autosomal recessive trait with affected homozygotes showing signs of reduced growth rate, shorter stature with kitten-like features, constipation and goitre. Hypothyroidism was confirmed by demonstrating low basal serum thyroxine levels which failed to increase after intravenous administration of thyroid stimulating hormone or thyrotropic releasing hormone. The radioiodide uptake of the thyroid glands was normal but a high proportion of the accumulated radioiodide was discharged after the administration of sodium perchlorate. It is concluded that the affected cats had a primary dyshormonogenesis: an organification (peroxidase) defect.

A recurrent marker chromosome involving chromosome 1 in two mammary tumors of the dog.

An apparently identical marker chromosome resulting from a chromosome 1. translocation was found in the mammary carcinomas of two bitches. Although these karyotypic aberrations were the sole clonal aberrations detected, it was not possible to unambiguously identify the material translocated to the chromosome 1 in either animal. Our observations, however, represent the first report of a recurring marker chromosome in mammary tumors of the dog and suggest that these tumors may become an interesting model for human breast cancer.

The expression of intermediate filaments in canine mammary glands and their tumors.

Monoclonal antibodies specific for different types of intermediate filaments (cytokeratin, vimentin, desmin and neurofilaments) were used to study the histogenesis of canine mammary glands and 57 canine mammary tumors by immunocytochemistry. The intra- and interlobular duct epithelium, acinar, and intralobular myoepithelial cells stained positively for cytokeratin. Peripheral ductal and acinar cells, as well as interstitial cells, stained positively for vimentin. A similar staining pattern was seen in adenomas, complex adenomas, benign mixed tumors, ductular carcinomas, and one myoepithelioma-like tumor. Additionally, cytokeratin positive cells were scattered interstitially in one single adenoma, most complex adenomas, some benign mixed tumors, complex carcinomas, and in the malignant mixed tumors. All stromal cells stained positively for vimentin. The fibrosarcomas were positive only for vimentin, while the following expressed both desmin and cytokeratin: epithelial-like cells in one adenoma, three complex adenomas, the myoepithelioma-like tumor, the single comedo carcinoma, two complex carcinomas, the single lobular carcinoma, one malignant mixed tumor, and three osteosarcomas. Epithelial-like cells in one adenoma, six complex adenomas, two benign mixed tumors, two complex carcinomas, the lobular carcinoma, and the malignant schwannoma stained for neurofilaments. Three tumors, one adenoma, one complex adenoma, and the lobular carcinoma expressed both desmin and neurofilaments in addition to cytokeratin and vimentin. The results show the expression of different types of intermediate filaments and indicate that there might be a stem cell origin in most of the canine mammary tumors.

Enhanced expression of class I major histocompatibility complex gene (Dk) products on immunogenic variants of a spontaneous murine carcinoma.

Both immunogenic and nonimmunogenic variant clones were isolated from a recently obtained spontaneous murine adenocarcinoma after treatment (xenogenization) with either the mutagen ethyl methanesulfonate or the DNA hypomethylating agent, and "gene activator," 5-azacytidine. Clonal analysis of the untreated tumor population confirmed that immunogenic variants arose as a consequence of the xenogenization protocol. At a dose of 10(6) cells per mouse, nonimmunogenic variants, like the parental tumor line, grew progressively in normal syngeneic recipients. In contrast, immunogenic variants were rejected in normal syngeneic mice and grew progressively only in T-cell-deficient nude mice. Serologic analysis of the respective clonal variants revealed that immunogenic variants expressed substantially elevated (fourfold to tenfold) levels of class I H-2Dk antigen relative to parental or nonimmunogenic cell lines. Two variants exhibiting marginal immunogenicity expressed high and low levels of major histocompatibility complex (MHC) antigen, respectively suggesting that elevated MHC expression, although possibly a contributing factor, did not account for the immunogenic phenotype in all cases. Finally, the immunogenic phenotype of two variants decayed with time in culture. Clones in the process of reversion lost their elevated Dk gene expression and became progressively more tumorigenic in normal syngeneic mice. Together, these data are consistent with a hypothesis that elevated MHC expression can contribute to the immunogenic phenotype of originally low MHC-expressing tumors and that the reduced level of MHC observed in certain clinical cancers may have significant implications with regard to immunologic aspects of the tumor-host relationship.

Tumors in dwarf galagos (Galagoides demidovii).

Three spontaneously occurring tumors are described in dwarf galagos. One tumor was a subcutaneous fibrous histiocytoma in the left inguinal area of an adult male; the other two were bile duct carcinomas in a seven-year-old male and a four-year-old female. Both bile duct carcinomas had remarkable invasive and metastasizing capacities.

[Cancer of the mammary gland in a tigress]. / Rak molochnoi zhelezy u samki tigra.

Mammary gland carcinoma in a 14-year-old female tiger kept in the Moscow Zoo for a long time is described. At autopsy, the outgrowth of the tumor into the surrounding tissue and metastases into the internal organs were found. The tumor was defined as a ductal papillary solid carcinoma with intraductal central necrosis that resembled the comedo type of human mammary gland carcinoma. Rapid growth of the tumor, the prevalence of necrosis, and numerous metastases to the lungs, liver, and lymph nodes were noted.