First description of feline inflammatory mammary carcinoma: clinicopathological and immunohistochemical characteristics of three cases

Cytological Features of Inflammatory Mammary Carcinoma in Dogs

BACKGROUND

Inflammatory mammary carcinoma (IMC) is the most aggressive and malignant type of mammary carcinoma. As in humans, canine IMC resembles mastitis clinically. However, IMC is highly aggressive with high incidence of metastases and common recurrence after surgery, leading to guarded prognosis and low survival rate. Given the complex morphology of canine mammary tumours, cytological examination is not performed routinely, and IMC diagnosis relies on the association of clinical features and histopathology. The purpose of this study is to describe the characteristics of canine IMC cytology, in an attempt to find possible cytological features that allow differentiation of IMC from other mammary tumour types.

METHODS

We analysed preoperative cytological samples from 25 dogs with IMC, later confirmed by corroborating clinical and histopathological examinations.

RESULTS

Distinct cytological features of canine IMC included scarce cellular cohesiveness, ballooning aspect of neoplastic cells, frequent multinucleation, irregularly dispersed and ropy chromatin pattern, and squamous metaplasia in some individualised cells or those in small groups.

CONCLUSIONS

Our results indicate that cytological examination can contribute to the diagnosis of IMC and might help differentiate it from other mammary carcinomas, even when clinical data is not available, which is common in cytological routine.

Evaluation of the efficacy and safety of toceranib phosphate in cats with macroscopic mammary adenocarcinoma

OBJECTIVES

Mammary tumours in cats are biologically aggressive. The standard of care relies upon wide surgical resection. Chemotherapy has been described in the macroscopic disease setting; however, limited efficacy has been shown. The aim of this study was to assess the efficacy of toceranib phosphate in macroscopic feline mammary tumours (FMTs).

METHODS

A total of 17 cats with cytologically or histopathologically confirmed mammary adenocarcinoma (gross disease) were prospectively enrolled. Toceranib phosphate was administered at a median dose of 2.77 mg/kg (range 2.3-3.2) PO q48 h. No corticosteroids or non-steroidal anti-inflammatory drugs (NSAIDs) were administered. Toxicity was graded according to Veterinary Cooperative Oncology Group-Common Terminology Criteria for Adverse Events (VCOG-CTCAE) v1.1 criteria. The response was assessed after 1 month, following Response Evaluation Criteria In Solid Tumours (RECIST) criteria.

RESULTS

Toxicity was observed in eight cats, with most instances being grade 1 or 2, which were managed with supportive care. Only one cat experienced grade 3 toxicity (anorexia), which resolved after a dose reduction. Clinical benefit was seen in 12 (64.7%) cats and an objective response was seen in six (35.2%) cats. One cat experienced complete response, five had partial response, six had stable disease and five had progressive disease. One cat showed distant progression (malignant pleural effusion) despite continued partial remission of the primary tumour. The median progression-free survival and median overall survival time were 91 days (range 30-158) and 145 days (range 31-234), respectively.

CONCLUSIONS AND RELEVANCE

Toceranib phosphate showed clinical benefit and a good safety profile in advanced or recurrent FMTs, offering a new alternative in the treatment of this disease; however, further prospective and randomised studies are required to further assess its efficacy. Interestingly, one cat developed distant metastases while the primary tumour showed partial response, suggesting that primary tumour and metastatic disease may not sustain the same sensitivity to toceranib.

Anaplastic Mammary Carcinoma in Cat

Clinical, pathological, and immunohistochemical findings related to a feline mammary tumor with similar features to canine anaplastic mammary carcinoma are herein described for the first time. A female cat was presented for clinical evaluation with gastrointestinal signs, oedema, erythema, and painful lesion in the right inguinal region. Three weeks later, the mass had doubled in size and radiographic revaluation of the thoracic cavity revealed a metastatic pattern. Due to the poor prognosis and decline of the clinical status the owners decided for euthanasia. Post-mortem examination exposed a mammary tumoral mass with subcutaneous oedema, an enlargement of the right inguinal lymph node, and nodules in several organs. Histological analysis confirmed the presence of large pleomorphic epithelial cells, often grouped in small clusters with bizarre nuclei. Immunohistochemical study of the different lesions was performed and both primary tumor and regional metastasis showed tumor cells to be negative estrogen receptor alpha, positive progesterone receptor, positive HER-2, and positive pan-cytokeratin. Given that the clinical history was compatible with an inflammatory mammary carcinoma, the cyclooxygenase-2 expression levels were evaluated and presented a weak immunoreactivity. Regarding the distant metastatic lesions, tumor cells were negative for ER-α and PR and, positive both for HER-2 and pan-cytokeratin.

Contraceptive implants used by cat breeders in France: a study of 140 purebred cats

OBJECTIVES

Deslorelin 4.7 mg and melatonin 18 mg subcutaneous implants were studied in purebred male and female cats, via questionnaires sent to French cat breeders, to assess breed, age, duration of the contraceptive effect, fertility after use, changes in behaviour and side effects.

METHODS

Reproductive data were collected in 57 tom cats and 41 queens implanted with deslorelin 4.7 mg, and 42 queens implanted with melatonin 18 mg, for a total of 140 purebred cats, from 38 different catteries, representing 18 breeds.

RESULTS

Using deslorelin (Suprelorin 4.7 mg; Virbac), sexual behaviour in males was inhibited for a mean ± SD of 13.4 ± 3.2 (range 8-21) months in 37/57 cats. Of these, 24/37 mated successfully and produced litters at a mean of 15.5 ± 3.6 (range 9-20) months. Inhibition lasted 11 ± 1.1 (range 9-12; n = 6), 13.2 ± 2.4 (range 12-18; n = 6) and 15 ± 3.5 (range 9-18; n = 6) months in Norwegian Forest Cat, Singapura and Ragdoll males, respectively. In 26/41 females implanted with deslorelin 4.7 mg, oestrus was inhibited for a mean of 16.0 ± 5.7 (8-38) months; 12/26 went on to produce a litter. Of the side effects specific to females: two presented persistent oestrus, leading to the removal of the implant; two developed lactation; one had fibroadenomatosis; and one was sterilised owing to cystic endometrial hyperplasia. Using melatonin (Melovine 18 mg; Ceva), 33/42 females had oestrus inhibited for a mean of 86 ± 50 (range 21-277) days after implantation with a peak return to oestrus in March, and 12/33 had a subsequent litter. No side effects were reported.

CONCLUSIONS AND RELEVANCE

This study is the first to collect a large amount of field data, in 140 purebred male and female cats where a deslorelin 4.7 mg or a melatonin 18 mg implant was used. These field results may allow for more accurate clinical advice and open up new avenues of research.

Her-2 expression in feline mammary lesions

Due to the high occurrence of mammary neoplasms in cats, the search for prognostic factors has recently intensified. Human epidermal growth factor receptor type 2 (Her-2) is prominent among the immunohistochemical markers used for prognosis. The aim of this study was to evaluate the expression of Her-2 in mammary lesions in queens and relate the expression to the type and histological grade of mammary carcinomas. Thirty-eight cases were selected from 2006 to 2016 and were classified and histologically graded. Her-2 expression was determined through immunohistochemistry, using a semi-quantitative analysis of the slides according to the scores recommended in the Dako HercepTest. Chi-square test was used to evaluate the relationship between Her-2 expression and mammary lesion type and the type and histological grade of carcinoma (P < 0.05). The mean age was 8.5 years and young cats were affected only by benign hyperplasias and neoplasms. Undefined cats were more affected (84.37%), followed by Siamese (9.37%) and Persian (6.25%) cats. Regarding the histological classification, 18.42% of the mammary lesions were classified as hyperplasia, 18.42% as adenoma, and 63.16% as carcinoma. The most common type of carcinoma was tubulopapillary carcinoma (66.7%), followed by solid carcinoma (25%) and cribriform carcinoma (8.33%). Her-2 overexpression was observed in four samples (16.7%) of tubulopapillary carcinoma, two grade I carcinomas and two grade II carcinomas, but no relationship was observed between Her-2 expression and type of mammary lesion (P = 0.3127), carcinoma type (0.3446), or histological grade (0.6485). In conclusion, Her-2 overexpression is unrelated to histological grade and type.

Translational pain assessment: could natural animal models be the missing link?

Failure of analgesic drugs in clinical development is common. Along with the current "reproducibility crisis" in pain research, this has led some to question the use of animal models. Experimental models tend to comprise genetically homogeneous groups of young, male rodents in restricted and unvarying environments, and pain-producing assays that may not closely mimic the natural condition of interest. In addition, typical experimental outcome measures using thresholds or latencies for withdrawal may not adequately reflect clinical pain phenomena pertinent to human patients. It has been suggested that naturally occurring disease in veterinary patients may provide more valid models for the study of painful disease. Many painful conditions in animals resemble those in people. Like humans, veterinary patients are genetically diverse, often live to old age, and enjoy a complex environment, often the same as their owners. There is increasing interest in the development and validation of outcome measures for detecting pain in veterinary patients; these include objective (eg, locomotor activity monitoring, kinetic evaluation, quantitative sensory testing, and bioimaging) and subjective (eg, pain scales and quality of life scales) measures. Veterinary subject diversity, pathophysiological similarities to humans, and diverse outcome measures could yield better generalizability of findings and improved translation potential, potentially benefiting both humans and animals. The Comparative Oncology Trial Consortium in dogs has pawed the way for translational research, surmounting the challenges inherent in veterinary clinical trials. This review describes numerous conditions similarly applicable to pain research, with potential mutual benefits for human and veterinary clinicians, and their respective patients.

Comparative aspects of canine and human inflammatory breast cancer

Inflammatory breast cancer (IBC) in humans is the most aggressive form of mammary gland cancer and shares clinical, pathologic, and molecular patterns of disease with canine inflammatory mammary carcinoma (CIMC). Despite the use of multimodal therapeutic approaches, including targeted therapies, the prognosis for IBC/CIMC remains poor. The aim of this review is to critically analyze IBC and CIMC in terms of biology and clinical features. While rodent cancer models have formed the basis of our understanding of cancer biology, the translation of this knowledge into improved outcomes has been limited. However, it is possible that a comparative "one health" approach to research, using a natural canine model of the disease, may help advance our knowledge on the biology of the disease. This will translate into better clinical outcomes for both species. We propose that CIMC has the potential to be a useful model for developing and testing novel therapies for IBC. Further, this strategy could significantly improve and accelerate the design and establishment of new clinical trials to identify novel and improved therapies for this devastating disease in a more predictable way.

Exploring new biomarkers in the tumour microenvironment of canine inflammatory mammary tumours

Human inflammatory breast cancer (IBC) and canine inflammatory mammary cancer (CIMC) are the most aggressive forms of mammary cancer. Current research aims to identify new therapeutic targets. Here, we investigated gene expression levels of biomarkers associated with the inflammatory microenvironment. A total of 32 formalin-fixed paraffin-embedded samples of canine mammary carcinoma (CIMC = 26; non-CIMC = 6) were used and their cDNA subjected to quantitative polymerase chain reaction (qPCR) to establish gene expression levels for mediators commonly implicated in linking carcinogenesis with inflammation. Gene expression differences between CIMC and non-CIMC types were obtained for cyclooxygenase 2 (COX-2) (P = 0.004), synuclein gamma (SNCG) (P = 0.006), tribbles 1 (P = 0.025), vascular endothelial growth factor (VEGF) (P = 0.017) and CSF1R (P = 0.045). Among these biomarkers correlations were found, particularly between SNCG and tribbles 1 (r = 0.512, P = 0.001). The efficient metastasis of CIMC is intimately linked to components in the tumour microenvironment. This study suggests that upregulation and correlation of SNCG and tribbles 1 deserves to be further explored.

Prognostic evaluation of feline mammary carcinomas: a review of the literature

A large number of studies have investigated feline mammary tumors in an attempt to identify prognostic markers and generate comparative analyses with human breast cancer. Nevertheless, a retrospective base of assessments and the lack of standardization in methodology and study design have caused weakness in study results, making comparison difficult. We examined feline mammary tumor publications and evaluated postulated prognostic parameters according to the recently published "Recommended Guidelines for the Conduct and Evaluation of Prognostic Studies in Veterinary Oncology." Using these criteria, we determined with statistically significant reliability that prognostic parameters for feline mammary tumors are tumor grading and lymph node/lymphovascular invasion. Furthermore, tumor subtype, size, and staging are worthy of further standardized investigation. We present statistical significance for each studied parameter as well as its relevance to disease progression and survival. Our evaluation suggests that marker expression (ie, Ki67, HER2, ER) may provide relevant information applicable for therapeutic predictions; however, consensus efforts and protocol standardization are needed. We identify and discuss major points of concern--such as sample preservation and selection, standardization of immunohistochemical protocols, and evaluation of results--to provide support for subsequent reliable analyses.

ERBB2 in cat mammary neoplasias disclosed a positive correlation between RNA and protein low expression levels: a model for erbB-2 negative human breast cancer

Human ERBB2 is a proto-oncogene that codes for the erbB-2 epithelial growth factor receptor. In human breast cancer (HBC), erbB-2 protein overexpression has been repeatedly correlated with poor prognosis. In more recent works, underexpression of this gene has been described in HBC. Moreover, it is also recognised that oncogenes that are commonly amplified or deleted encompass point mutations, and some of these are associated with HBC. In cat mammary lesions (CMLs), the overexpression of ERBB2 (27%-59.6%) has also been described, mostly at the protein level and although cat mammary neoplasias are considered to be a natural model of HBC, molecular information is still scarce. In the present work, a cat ERBB2 fragment, comprising exons 10 to 15 (ERBB2_10-15) was achieved for the first time. Allelic variants and genomic haplotype analyses were also performed, and differences between normal and CML populations were observed. Three amino acid changes, corresponding to 3 non-synonymous genomic sequence variants that were only detected in CMLs, were proposed to damage the 3D structure of the protein. We analysed the cat ERBB2 gene at the DNA (copy number determination), mRNA (expression levels assessment) and protein levels (in extra- and intra protein domains) in CML samples and correlated the last two evaluations with clinicopathological features. We found a positive correlation between the expression levels of the ERBB2 RNA and erbB-2 protein, corresponding to the intracellular region. Additionally, we detected a positive correlation between higher mRNA expression and better clinical outcome. Our results suggest that the ERBB2 gene is post-transcriptionally regulated and that proteins with truncations and single point mutations are present in cat mammary neoplastic lesions. We would like to emphasise that the recurrent occurrence of low erbB-2 expression levels in cat mammary tumours, suggests the cat mammary neoplasias as a valuable model for erbB-2 negative HBC.

Mammary tumours in the cat: size matters, so early intervention saves lives

PRACTICAL RELEVANCE

Mammary tumours are among the most common neoplasms in both cats and dogs, but the prevalence of malignant histological types is far higher in cats (ratio of malignant:benign is at least 4:1).

CLINICAL CHALLENGES

The more aggressive nature of mammary neoplasia in cats poses challenges for management. Prognosis is affected by tumour size and, therefore, early recognition and treatment of mammary tumours is paramount. Although the primary tumour can be excised surgically, no studies have shown that chemotherapy significantly extends survival time; hence, metastatic spread remains an important clinical problem.

PATIENT GROUP

Mammary tumours usually affect older female cats, mainly entire females. Siamese and Oriental breeds may be predisposed. Male cats can develop mammary neoplasia, but this is rare.

EVIDENCE BASE

This review summarises the current literature relating to aetiology, pathology, presentation, diagnosis, staging, treatment and prognosis of feline mammary tumours.

A case of feline primary inflammatory mammary carcinoma: clinicopathological and immunohistochemical findings

The clinicopathological and immunohistochemical findings of a primary feline mammary tumour with features similar to human and canine primary inflammatory carcinoma are described for the first time. The cat presented to the clinic for the rapid onset of oedema, severe erythema, local pain and warmth of the inguinal region, with a pustular-to-nodular cutaneous lesion in association with an ill-defined underlying mass. An epithelial malignant tumour was diagnosed by cytological investigation. Necropsy revealed a thickening of the skin with oedema of the subcutis in the right inguinal area, and regional and distant metastases. Histology showed an unencapsulated tubulopapillary proliferation of malignant epithelial cells, with a massive embolisation in the dermal lymphatics and a mild inflammatory infiltrate. Through immunohistochemistry, the tumour was found to be oestrogen (ER)-alpha-, androgen (AR)- and progesterone (PR)-negative; neoplastic cells were ER-alpha, AR-negative and focally PR-positive. An irregular, mild and focal HER-2 immunoreactivity was present (score +1, non-HER-2 overexpressing). The neoplastic cells were cyclo-oxygenase-2 and vascular endothelial growth factor positive.

Inflammatory mammary carcinoma with metastasis to the brain and distant organs in a spayed Shih Tzu dog

Inflammatory mammary carcinoma (IMC) is a specific type of rare, very aggressive, and highly metastatic mammary cancer in both human beings and dogs. A 10-year-old female spayed Shih Tzu dog was diagnosed with secondary IMC. At necropsy, brain metastasis of mammary neoplastic cells was observed in tissues of the cerebrum and cerebellum. Metastases were also found in other distant organs such as heart, lung, liver, spleen, and inguinal lymph node. There is limited data about the metastasis of IMC and its pattern. The current report of IMC with brain metastases contributes to the understanding of metastatic IMC.

Early detection, aggressive therapy: optimizing the management of feline mammary masses

AIMS

This article reviews the incidence, etiology, diagnosis, treatment and prognosis of mammary tumors in cats.

PRACTICAL RELEVANCE

Approximately 80% of feline mammary masses are malignant, with adenocarcinoma being the most common tumor type. Early diagnosis is, therefore, essential to improve the prognosis and quality of life of affected cats.

TREATMENT APPROACHES

Surgery is the most widely used treatment for malignant tumors. However, as mammary tumors are often advanced and metastasis has already occurred by the time of diagnosis, surgery routinely does not provide a cure. Ovariohysterectomy or hormonal therapy are the treatments of choice for fibroadenomatous hyperplasia (the most common benign mass) and usually lead to a successful outcome.

Molecular plasticity of E-cadherin and sialyl lewis x expression, in two comparative models of mammary tumorigenesis

Background

The process of metastasis involves a series of steps and interactions between the tumor embolus and the microenvironment. Key alterations in adhesion molecules are known to dictate progression from the invasive to malignant phenotype followed by colonization at a distant site. The invasive phenotype results from the loss of expression of the E-cadherin adhesion molecule, whereas the malignant phenotype is associated with an increased expression of the carbohydrate ligand-binding epitopes, (e.g. Sialyl Lewis ^x/a) that bind endothelial E-selectin of the lymphatics and vasculature.

Methodology

Our study analyzed the expression of two adhesion molecules, E-cadherin and Sialyl Lewis x (sLe^x), in both a canine mammary carcinoma and human inflammatory breast cancer (IBC) model, using double labelled immunofluorescence staining.

Results

Our results demonstrate that canine mammary carcinoma and human IBC exhibit an inversely correlated cellular expression of E-cadherin and sLe^x within the same tumor embolus.

Conclusions

Our results in these two comparative models (canine and human) suggest the existence of a biologically coordinated mechanism of E-cadherin and sLe^x expression (i.e. molecular plasticity) essential for tumor establishment and metastatic progression.

Selection of reference genes for quantitative real-time PCR analysis in canine mammary tumors using the GeNorm algorithm

Eleven reference genes (18s ribosomal ribonucleic acid [RNA], 28s ribosomal RNA, ubiquitin, beta-actin, glycerine aldehyde dehydrogenase, ATP-synthase subunit 5B, hydroxymethyl-bilane synthase, hypoxanthine-phosphoribosyl transferase, ribosomal protein L32, tryptophan 5-monooxygenase activation protein (zeta polypeptide), and TATA-Box binding protein) were analyzed in use as references for gene expression profiling experiments using quantitative reverse transcription polymerase chain reaction (qRT-PCR) in canine mammary tumors. The transcription level of the candidates was measured in 22 histologically characterized excised tumor specimens from mammary gland tissue and 22 samples of non-neoplastic mammary tissue samples from the same individuals. Results were used to rank candidate reference genes using the GeNorm tool. It was determined that in samples of canine mammary gland tissue, a combination of hypoxanthine-phosphoribosyl transferase, ATP-synthase subunit 5B, ribosomal protein L32 and ubiquitin yields stable reference gene expression levels, whereas the use of glycerin aldehyde dehydrogenase or ribosomal RNA is unsuitable for normalization of qRT-PCR results in this tissue type.

Steroids and receptors in canine mammary cancer

The aims of this study were to investigate the serum and tissue content of androgens and estrogens in canine inflammatory mammary carcinomas (IMC) as well as in non-inflammatory malignant mammary tumors (MMT), and assessed the immunoexpression of estrogen and androgen receptors using immunohistochemistry. Profiles for the androgens dehydroepiandrosterone (DHEA), androstenedione (A4), and testosterone (T), and for the estrogens 17beta estradiol (E2) and estrone-sulphate (SO4E1) were measured both in tissue homogenates and in serum of MMT and IMC by EIA techniques in 42 non-inflammatory malignant mammary tumors (MMT) and in 14 inflammatory mammary carcinomas (IMC), prospectively collected from 56 female dogs. Androgen receptor (AR) and estrogen receptor alpha (ERalpha) and beta (ERbeta) expression was studied using immunohistochemistry (strepavidin-biotin-peroxidase method) in samples of 32 MMT and 14 IMC, and counted by a computer image analyzer. IMC serum and tissue levels of androgens were significantly higher than MMT levels. Tissue content of estrogens was also significantly higher in IMC than in MMT. Serum values of SO4E1 were significantly higher in IMC, but serum levels of E2 were significantly lower in IMC compared to MMT cases. Medium-high androgen receptor intensity was observed in 64.28% of IMC and 40.62% of MMT. No important differences were found between ERalpha expression in IMC (100% negative) and MMT (90% negative). ERbeta and AR were intensely expressed in highly malignant inflammatory mammary carcinoma cells. To our knowledge, this is the first report relative to AR immunohistochemistry in canine mammary cancer and to estrogens or androgens in serum of dogs with benign or malignant mammary tumors.