Neoplastic Tumor Research Articles

A Forgotten Rare Cause of Unilateral Basal Ganglia Calcinosis Due to Venous Angioma and Complicating Acute Stroke Management: A Case Report

Background: Unilateral basal ganglia calcinosis (BGC) is a rare radiological finding that can be diagnosed on computed tomography (CT) and magnetic resonance imaging (MRI) but often presents challenges for clinicians and radiologists in determining its underlying cause. So far, only a few potential causes that could explain unilateral BGC have been described in the literature. Case Report: A 54-year-old Caucasian male was admitted to a tertiary university hospital due to the sudden onset of speech impairment and right-sided weakness. The patient had no significant medical history prior to this event. Non-enhanced computed tomography (NECT) of the brain revealed no evidence of acute ischemia; CT angiography (CTA) showed acute left middle cerebral artery (MCA) M2 segment occlusion. CT perfusion (CTP) maps revealed an extensive penumbra-like lesion, which is potentially reversible upon achieving successful recanalization. However, a primary neoplastic tumor with calcifications in the basal ganglia was initially interpreted as the potential cause; therefore, acute stroke treatment with intravenous thrombolysis was contraindicated. A follow-up CT examination at 24 h revealed an ischemic lesion localized to the left insula, predominantly involving the left parietal lobe and the superior gyrus of the left temporal lobe. Subsequent gadolinium-enhanced brain MRI revealed small blood vessels draining into the subependymal periventricular veins on the left basal ganglia. Digital subtraction angiography was conducted, confirming the diagnosis of venous angioma. Conclusions: Unilateral BGC caused by venous angioma is a rare entity with unclear pathophysiological mechanisms and heterogeneous clinical presentation. It may mimic conditions such as intracerebral hemorrhage or hemorrhagic brain tumors, complicating acute stroke management, as demonstrated in this case. Surrounding tissue calcification may provide a valuable radiological clue in diagnosing venous angiomas DVAs and vascular malformations.

Natural killer cells occupy unique spatial neighborhoods in HER2- and HER2+ human breast cancers

Tumor-infiltrating lymphocytes are considered clinically beneficial in breast cancer, but the significance of natural killer (NK) cells is less well characterized. As increasing evidence has demonstrated that the spatial organization of immune cells in tumor microenvironments is a significant parameter for impacting disease progression as well as therapeutic responses, an improved understanding of tumor-infiltrating NK cells and their location within tumor contextures is needed to improve the design of effective NK cell-based therapies. In this study, we developed a multiplex immunohistochemistry (mIHC) antibody panel designed to quantitatively interrogate leukocyte lineages, focusing on NK cells and their phenotypes, in two independent breast cancer patient cohorts (n = 26 and n = 30). Owing to the clinical evidence supporting a significant role for NK cells in HER2+ breast cancer in mediating responses to Trastuzumab, we further evaluated HER2- and HER2+ specimens separately. Consistent with literature, we found that CD3+ T cells were the dominant leukocyte subset across breast cancer specimens. In comparison, NK cells, identified by CD56 or NKp46 expression, were scarce in all specimens with low granzyme B expression indicating reduced cytotoxic functionality. Whereas NK cell density and phenotype did not appear to be influenced by HER2 status, spatial analysis revealed distinct NK cells phenotypes regarding their proximity to neoplastic tumor cells that associated with HER2 status. Spatial cellular neighborhood analysis revealed multiple unique neighborhood compositions surrounding NK cells, where NK cells from HER2- tumors were more frequently found proximal to neoplastic tumor cells, whereas NK cells from HER2+ tumors were instead more frequently found proximal to CD3+ T cells. This study establishes the utility of quantitative mIHC to evaluate NK cells at the single-cell spatial proteomics level and illustrates how spatial characteristics of NK cell neighborhoods vary within the context of HER2- and HER2+ breast cancers.

Retrospective Clinicopathological Study of 33 Cases of Pleomorphic Salivary Adenoma Diagnosed in Benghazi

Background: Pleomorphic salivary adenoma (PSA) is the most frequently found neoplastic tumor in major and minor salivary glands. It has a high recurrence rate and there is a possibility for benign PSA to transform into malignant form. No study on clinical and histopathological features of pleomorphic adenoma in Libya was found. occurrence of benign PSA is more common than PSA with malignant foci. Aim: The present study aimed to retrospectively analyze the clinical and histopathological features of cases diagnosed as pleomorphic adenoma and compare our findings to those of other studies. Materials and Methods: In this retrospective study, the pleomorphic salivary adenoma cases diagnosed between 1994-2019 in the Department of Oral Pathology, Dental School, University of Benghazi, Libya were retrieved. The diagnosis was confirmed by reevaluation of hematoxylin and eosin-stained slides. Descriptive statistics were used to describe the clinical data of the patient’s demographics and clinical features of the tumor. Results: It was found that among 33 diagnosed cases of PSA, 11 cases were males and 22 cases were females. The most common age range was 10-29 years (21 cases). The most common intra-oral site was the palate (15 cases) followed by buccal mucosa (6 cases) and submandibular glands and parotid glands were most commonly affected among major salivary glands. Benign pleomorphic adenoma (24 cases) was most common, myoepithelium was reported in 2 cases and malignant foci were reported in 7 cases. Conclusion: This study revealed that Females were more affected than males. The most common location of pleomorphic adenoma was the palate. The myoepithelioma is a rare.

The role of methionine cycle disruption in the initiation and progression of malignant tumors

The methionine cycle is responsible for the metabolism of substances associated with methionine, one of the essential amino acids for protein synthesis. The methionine cycle dysregulation leads to non-proteinogenic amino acid homocysteine accumulation that can have a negative impact on a health. Numerous studies describe homocysteine effect on cardiovascular pathology development but its role in carcinogenesis remains poorly understood. Therefore, the purpose of this review is to analyze scientific data regarding the role of methionine catabolism dysregulation in a cell neoplastic transformation and tumor growth. Understanding cellular alterations of methionine metabolism is important for novel anti-cancer drugs development as well as establishing approaches for combinatorial treatment strategies aiming to overcome metabolic plasticity of cancer cells and their drug resistance.

Grisotti flap technique in the management of central breast neoplastic tumours

Grisotti flap technique in the management of central breast neoplastic tumours

Abstract IA027: Age-related stromal changes drive breast cancer tumor progression

Abstract Age is the single largest risk factor for the development of cancer, but how age impacts the molecular mechanisms that drive cancer remain poorly understood. While it is clear that age-related accumulation of cell autonomous mutations contributes to tumorigenesis, the central role age-related changes in the tumor microenvironment play in the transformation process is becoming more fully appreciated. Underscoring the importance of an aged microenvironment in cancer development are findings that senescent fibroblasts, which accumulate with age, directly stimulate preneoplastic and neoplastic cell growth and tumor progression. Investigations into how senescent fibroblasts promote tumorigenesis revealed that they express a plethora of growth factors, extracellular matrix remodeling enzymes, chemokines, and cytokines collectively referred to as the senescence associated secretory phenotype (SASP). Chemotherapy induces similar changes that can negatively impact a patient’s quality of life. We will discuss how these changes impact tumor progression and therapy-induced bone loss. Citation Format: Sheila A. Stewart. Age-related stromal changes drive breast cancer tumor progression [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr IA027.

Rare Combination of Multiple Endocrine Neoplasia 1 with Medullary Thyroid Carcinoma and Clinical Value of 68Ga-DOTATATE PET/CT in Diagnosing Different Lesions and Exploring Theranostic Strategy

AbstractMultiple endocrine neoplasia type 1 (MEN1) syndrome is characterized by the presence of hyperplastic or neoplastic tumors in the parathyroid, pituitary, and gastroenteropancreatic endocrine tissues. The presence of lesions in at least two out of the three glands (pituitary, parathyroid, and pancreas) is indicative of MEN1 syndrome. Medullary thyroid carcinoma (MTC) is a type of tumor that originates from the parafollicular C cells of the thyroid gland. It is frequently found as part of MEN2 syndrome. MEN1 with MTC is a relatively uncommon occurrence. We report a rare case of MTC that later on developed parathyroid carcinoma, pituitary microadenoma, pancreatic neuroendocrine tumor (NET), and duodenal NET. The case was identified as part of MEN1 syndrome using exome sequencing and somatostatin receptor–based functional imaging 68Ga-DOTATATE positron emission tomography/computed tomography was employed for exploring theranostic strategy in the management of the patient.

Adverse Events of Radioligand Therapy in Patients with Progressive Neuroendocrine Neoplasms: The Biggest Eastern European Prospective Study.

Neuroendocrine neoplasms (NENs) are neoplastic tumors developing in every part of the body, mainly in the gastrointestinal tract and pancreas. Their treatment involves the surgical removal of the tumor and its metastasis, long-acting somatostatin analogs, chemotherapy, targeted therapy, and radioligand therapy (RLT). A total of 127 patients with progressive neuroendocrine neoplasms underwent RLT-4 courses, administered every 10 weeks-with the use of 7.4 GBq [177Lu]Lu-DOTA-TATE or tandem therapy with 1.85 GBq [177Lu]Lu-DOTA-TATE and 1.85 GBq [90Y]Y-DOTA-TATE. Assessment of short- and long-term complications, as well as the calculation of progression-free survival (PFS) and overall survival (OS) were performed. RLT caused a statistically but not clinically significant decrease in blood morphology parameters during both short- and long-term observations. Glomerular filtration rate (GFR) significantly decreased only in a long-term observation after RLT; however, it was clinically acceptable. Computed predictions of progression-free survival (PFS) and overall survival (OS) indicated that five years post-RLT, there is a 74% chance of patients surviving, with only a 58.5% likelihood of disease progression. Computed predictions of PFS and OS confirmed treatment efficiency and good patient survival. RLT should be considered a safe and reliable line of treatment for patients with progressive NENs as it causes only a low number of low-grade adverse events.

Posterior uveal biopsy and the trans-scleral Essen forceps biopsy technique.

Differentiating neoplastic and non-neoplastic uveal tumours can present a diagnostic challenge; intra-ocular biopsy may be necessary. The novel trans-scleral Essen Forceps biopsy (TSEB) technique can improve diagnostic yield compared to fine needle aspiration biopsy (FNAB). We present a case demonstrating the technique and its added value. We also review the success rate of TSEB performed at two tertiary eye centres. Retrospective case report and consecutive case series from August 2021 to March 2023. Inclusion criteria were patients who underwent TSEB of posterior uveal lesions from Moorfields Eye Hospital and Sheffield Teaching Hospitals in the United Kingdom. The outcomes were biopsy success rate and complication rate RESULTS: Eleven biopsies met the inclusion criteria. Eight (73%) were successful, which comprised six uveal melanomas, one melanocytoma and one extranodal marginal zone (ENMZ) lymphoma. One TSEB did not yield tissue for histological examination because of perioperative sample handling. Two (18%) biopsies were histologically inconclusive; both were treated as uveal melanoma on clinical grounds or repeat biopsy. The only complication was vitreous loss and retinal hole without retinal detachment in one eye with a very posterior, shallow choroidal lesion. TSEB is an effective alternative to established biopsy techniques, yielding larger tissue samples than FNAB with intact tissue architecture. We recommend adding TSEB to the armamentarium of the ocular oncologist.

Prognostic and Predictive Roles of HER2 Status in Non-Breast and Non-Gastroesophageal Carcinomas.

The oncogene ERBB2, also known as HER2 or c-ERB2, is located on chromosome 17 (q12). It encodes a tyrosine kinase receptor, the human epidermal growth factor receptor 2 (HER2), involved in neoplastic proliferation, tumor angiogenesis, and invasiveness. Over the past years, the introduction of various anti-HER2 therapies has significantly improved outcomes for patients with HER2-positive breast and gastroesophageal carcinomas. More recently, the introduction of a new antibody-drug conjugate, that is trastuzumab deruxtecan, expanded the therapeutic options to low-HER2 breast and gastroesophageal tumors. HER2 protein overexpression is investigated using immunohistochemistry, gene amplification using fluorescence in situ hybridization, and gene mutation using next-generation sequencing. This review evaluated the predictive and prognostic role of HER2 status in various types of epithelial malignant cancers beyond breast and gastroesophageal cancers. We critically analyzed the key published studies, focusing on utilized scoring systems and assays used, and analyzed clinical parameters and therapeutic approaches. Although the evidence about prognostic and predictive roles of HER2 in carcinomas other than breast and gastroesophageal has been widely increasing over the last decade, it still remains investigational, revealing a tumor site-related prognostic and predictive value of the different types of HER2 alterations. However, standardized and validated scoring system assays have not been well-established for many organs.

Monitoring Breast Cancer Response to Neoadjuvant Chemotherapy Using Probability Maps Derived from Quantitative Ultrasound Parametric Images.

Neoadjuvant chemotherapy (NAC) is widely used in the treatment of breast cancer. However, to date, there are no fully reliable, non-invasive methods for monitoring NAC. In this article, we propose a new method for classifying NAC-responsive and unresponsive tumors using quantitative ultrasound. The study used ultrasound data collected from breast tumors treated with NAC. The proposed method is based on the hypothesis that areas that characterize the effect of therapy particularly well can be found. For this purpose, parametric images of texture features calculated from tumor images were converted into NAC response probability maps, and areas with a probability above 0.5 were used for classification. The results obtained after the third cycle of NAC show that the classification of tumors using the traditional method (area under the ROC curve AUC = 0.81-0.88) can be significantly improved thanks to the proposed new approach (AUC = 0.84-0.94). This improvement is achieved over a wide range of cutoff values (0.2-0.7), and the probability maps obtained from different quantitative parameters correlate well. The results suggest that there are tumor areas that are particularly well suited to assessing response to NAC. The proposed approach to monitoring the effects of NAC not only leads to a better classification of responses, but also may contribute to a better understanding of the microstructure of neoplastic tumors observed in an ultrasound examination.

Raman spectroscopy for classification of neoplastic and non-neoplastic CAM colon tumors

This paper demonstrates the potential of Raman spectroscopy for differentiating neoplastic from non-neoplastic colon tumors, obtained with the CAM (chicken chorioallantoic membrane) model. For the CAM model two human cell lines were used to generate two types of tumors, the RKO cell line for neoplastic colon tumors and the NCM460 cell line for non-neoplastic colon tumors. The Raman spectra were acquired with a 785 nm excitation laser. The measured Raman spectra from the CAM samples (n = 14) were processed with several methods for baseline correction and to remove artifacts. The corrected spectra were analyzed with PCA (principal component analysis). Additionally, machine learning based algorithms were used to create a model capable of classifying neoplastic and non-neoplastic tumors. The principal component scores showed a clear differentiation between neoplastic and non-neoplastic colon tumors. The classification model had an accuracy of 93 %. Thus, a complete methodology to process and analyze Raman spectra was validated, using a rapid, accessible, and well-established tumor model that mimics the human tumor pathology with minor ethical concerns.

The JNK and Hippo pathways control epithelial integrity and prevent tumor initiation by regulating an overlapping transcriptome

Epithelial organs maintain their integrity and prevent tumor initiation by actively removing defective cells, such as those that have lost apicobasal polarity. Here, we identify how transcription factors of two key signaling pathways-Jun-N-terminal kinase (JNK) and Hippo-regulate epithelial integrity by controlling transcription of an overlapping set of target genes. Targeted DamID experiments reveal that, in proliferating cells of the Drosophila melanogaster eye, the AP-1 transcription factor Jun and the Hippo pathway transcription regulators Yorkie and Scalloped bind to a common suite of target genes that promote organ growth. In defective neoplastic cells, AP-1 transcription factors repress transcription of growth genes together with the C-terminal binding protein (CtBP) co-repressor. If gene repression by AP-1/CtBP fails, neoplastic tumor growth ensues, driven by Yorkie/Scalloped. Thus, AP-1/CtBP eliminates defective cells and prevents tumor initiation by acting in parallel to Yorkie/Scalloped to repress expression of a shared transcriptome. These findings shed new light on the maintenance of epithelial integrity and tumor suppression.

Composite hemangioendothelioma of breast: A case report with review of literature

Composite hemangioendothelioma (CHE) is an intermediate grade neoplastic tumor of vascular origin. It consists of a varied mixture of benign, intermediate and malignantvascular components. Only few cases of CHE occurring in different soft tissue areas of the body and rarely in internal organs have been reported in literature till now. We report a case of CHE presenting as lump in the breast in a 42 year old female. A review of literature is also presented to create awareness of this entity which can be misleading in breast where angiosarcoma is also known to occur.

Novel method of image analysis that combines Radon and Fourier image transformations for the purpose of differentiating between malignant and benign colonic biopsies.

Colorectal cancer is the third most common type of cancer. It develops slowly as a polyp that can turn into a cancerous tumor. This study aimed to develop a decision-making algorithm of microscopic images using texture analysis that is orientation free, to be used for automated classification of normal and neoplastic (malignant or premalignant) colonic biopsies. Forty-nine colonic adenocarcinomas, 41 adenomas and a control group of adjacent normal colonic mucosa were included in the texture analysis. Radon transform followed by the Fast Fourier transform were applied to the images. Subsequently, the gray level co-occurrence matrix (GLCM) transform was applied allowing the extraction of four textural variables (homogeneity, contrast, correlation, and entropy). For classification and prediction of the diagnosis, a statistical multivariate regression model and a neural network (NNET) model were used and compared. The statistical model provided a sensitivity of 71.3% and a specificity of 50% (Area under the ROC curve: 0.67) for classifying the neoplastic and the normal images, respectively. The NNET model was superior to the statistical model and produced a sensitivity of 97.9% and specificity of 88% (Area under the ROC curve: 0.92). To our knowledge, this is the first study that used a combination of Radon, FFT, and GLCM transformations in order to overcome the tissue orientation problem in texture analysis of microscopic images of colonic biopsies. The NNET classifier trained by the extracted textural features proved to be superior to the statistical classifier, thus predicting colonic neoplasia with high accuracy. RESEARCH HIGHLIGHTS: We propose a novel decision-making algorithm of orientation invariant image texture analysis, fast and easily implemented for automated differentiation between benign and neoplastic epithelial tumors of the colon. This method can reduce the turnaround time allowing to prioritize the biopsies during their examination and diagnosis by the pathologist.

Proteomic analysis of pleomorphic dermal sarcoma reveals a fibroblastic cell of origin and distinct immune evasion mechanisms

Pleomorphic dermal sarcomas are infrequent neoplastic skin tumors, manifesting in regions of the skin exposed to ultraviolet radiation. Diagnosing the entity can be challenging and therapeutic options are limited. We analyzed 20 samples of normal healthy skin tissue (SNT), 27 malignant melanomas (MM), 20 cutaneous squamous cell carcinomas (cSCC), and 24 pleomorphic dermal sarcomas (PDS) using mass spectrometry. We explored a potential cell of origin in PDS and validated our findings using publicly available single-cell sequencing data. By correlating tumor purity (TP), inferred by both RNA- and DNA-sequencing, to protein abundance, we found that fibroblasts shared most of the proteins correlating to TP. This observation could also be made using publicly available SNT single cell sequencing data. Moreover, we studied relevant pathways of receptor/ligand (R/L) interactions. Analysis of R/L interactions revealed distinct pathways in cSCC, MM and PDS, with a prominent role of PDGFRB-PDGFD R/L interactions and upregulation of PI3K/AKT signaling pathway. By studying differentially expressed proteins between cSCC and PDS, markers such as MAP1B could differentiate between these two entities. To this end, we studied proteins associated with immunosuppression in PDS, uncovering that immunologically cold PDS cases shared a “negative regulation of interferon-gamma signaling” according to overrepresentation analysis.

Application of Endoscopic Submucosal Dissection (ESD) in Treatment of Gastrointestinal Lesions-Single Center Experience.

Background and Objectives: Endoscopic resection of gastrointestinal (GI) tract lesions, originating from Japan, is becoming more frequently used in European countries. Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) ensure minimally invasive removal of benign, premalignant, and early neoplastic tumors of esophagus, stomach, and intestine in selected group of patients. Aim of this study was to determine the outcomes, radical resection rate (R0), and complication rate of ESD procedures performed in our department. Methods: The data from 100 ESD procedures of esophageal, gastric, duodenal, and colorectal lesions performed in out unit between 02.01.2020 and 30.06.2023 were collected and analyzed retrospectively. Results: A total of 42 male and 58 female patients in the median age of 64 years (range, 31-89 years) underwent ESD. Mean duration of the procedure was 66 minutes (ranging 25-185 minutes). Tumors were located in the esophagus in 8 cases (8%), stomach in 25 cases (25%), duodenum in 1 case (1%), and colon in 66 cases (66%). Radical resection was achieved in 98 cases (98%); 2 patients were qualified for surgical treatment. Average size of dissection lesions was 26 × 19 mm. The biggest one was 60 × 60 mm (sigmoid adenoma), and the smallest one was 5 × 5 mm (gastrointestinal neuroectodermal tumors). Complication occurred in 10 patients (10%)-9 perforations of the wall of intestine (9%) and 1 hemorrhage, which required endoscopic intervention (1%). Conclusions: Implementation of ESD to clinical practice gives the opportunity for minimally invasive, radical treatment of benign, premalignant, and early neoplastic lesions of gastrointestinal tract in selected group of patients. Experienced endoscopists, following current guidelines and standardized process of qualification, are crucial to minimize the risk of severe complications.

Hepatic hemangioma in a simple liver cyst mimicking biliary cystic neoplasm

BackgroundFollow-up is recommended for an asymptomatic unilocular hepatic cystic lesion without wall-thickness and nodular components. A few liver cystic lesions represent biliary cystic neoplasms, which are difficult to differentiate from simple cysts with benign mural nodules on imaging alone.Case presentationAn 84-year-old woman with a history of simple liver cyst diagnosed one year prior was admitted for evaluation of a developed mural nodule in the cystic lesion. She had no specific symptoms and no abnormalities in blood tests except for carcinoembryonic antigen (5.0 ng/mL) and carbohydrate antigen (43.5 U/mL) levels. Contrast-enhanced computed tomography revealed a well-defined, low-attenuation lesion without a septum that had enlarged from 41 to 47 mm. No dilation of the bile duct was observed. A gradually enhancing mural nodule, 14 mm in diameter, was confirmed. MRI revealed a uniform water-intense cystic lesion with a mural nodule. This was followed by T2-enhanced imaging showing peripheral hypointensity and central hyperintensity. Enhanced ultrasonography revealed an enhanced nodule with a distinct artery within it. A needle biopsy of the wall nodule or aspiration of intracystic fluid was not performed to avoid tumor cell spillage. The possibility of a neoplastic cystic tumor could not be ruled out, so a partial hepatectomy was performed with adequate margins. Pathologically, the cystic lesion contained a black 5 mm nodule consisting of a thin, whitish fibrous wall and dilated vessels lined by CD31 and CD34 positive endothelial cells. The final diagnosis was a rare cavernous hemangioma within a simple liver cyst.ConclusionsCavernous hemangiomas mimicking well-enhanced mural nodules can arise from simple liver cysts. In less malignant cases, laparoscopic biopsy or percutaneous targeted biopsy of the mural nodules, together with needle ablation, may be recommended to avoid unnecessary surgery.

Unicystic Ameloblastoma Mural Variant: A Case Report

Background: Ameloblastomas are a rare type of benign neoplastic tumors that are locally invasive and make up around 1% of all head-and-neck tumors. Mostly diagnosed in people between the ages of 30 and 60 years, it has a global incidence of about 0.5% of cases per million person years. Ameloblastomas are classified as multicystic, unicystic, peripheral, and desmoplastic variants. Unicystic ameloblastomas (UAs), accounting for about 6% of the cases, have a high recurrence rate. It is histologically divided into luminal, intraluminal, and mural types. As the mural variant is aggressive and has the highest chance of recurrence, radical resection of tumor is required. Case Presentation: A case of 47-year-old patient, diagnosed as unicystic mural variant of ameloblastoma presented to us in March 2023 at the department of head-and-neck surgery at a tertiary care setup in Karachi, Pakistan. Postoperatively, the patient is now on 6-month follow-up with no residual or recurrence report as of yet. Conclusion: We report a rare case of UA mural variant in the right mandible, which highlights the importance of prompt diagnosis and treatment of this type of ameloblastoma, particularly in a location where they can cause significant damage.

Risk factor analysis and clinicopathological characteristics of female dogs with mammary tumours from a single-center retrospective study in Poland

This is a comprehensive retrospective study to characterize female dogs with canine mammary tumors (CMTs) using a dataset retrieved from the archives of the Division of Animal Pathology, Institute of Veterinary Medicine in Warsaw, and to identify prognostic factors. Clinical and histopathological data of 1447 dogs with CMTs were included. Malignant tumours were found in 83.3% (n = 1206), benign tumours in 11.7% (n = 169), and non-neoplastic lesions in 5.0% (n = 72) of dogs. Dogs most often had grade II carcinomas (38.2%, 215/562) of a single histological subtype (88.5%, 1281/1447), mostly simple carcinoma (35.3%, 510/1447). Dogs with a median age of 10 years significantly often had larger (≥ 3 cm) and malignant CMTs, whereas intact females had smaller tumours (median size 2.0 cm). However, the threshold value for the age of the dog in the differentiation of malignant and non-neoplastic/benign masses could not be determined. Most females were hormonally active (76.4%, 372/487). Hormonally active dogs significantly more often had multiple tumours. Multiple tumours were significantly smaller (median 2.5 cm) than single ones. Among pedigree dogs, small-breed dogs were mostly recorded (43%, 428/1006). Twelve breeds had an increased risk of CMTs, regardless of tumour behaviour, compared with the theoretical distribution of pedigree dogs in Poland. Four breeds were often affected only by malignant and other four breeds only by non-neoplastic/benign CMT. Large-breed dogs were significantly younger and affected by larger CMT (median 4 cm) compared with small- and medium-breed dogs. Ninety dogs with a malignant CMT and complete records were included in the full analysis of CMT-specific survival (CMT-SS) with a median follow-up time of 20.0 months. We showed that the timing of ovariohysterectomy in relation to mastectomy was significantly associated with grade, CMT-SS, and CMT-related death. We indicated the low diagnostic accuracy of palpation of regional lymph nodes (RLN) in the prediction of their metastatic involvement. By multivariable analysis, dogs with neoplastic emboli, tumour ulceration, and simple or complex carcinoma had a significantly higher risk of local recurrence. Tumour size > 3 cm was as a strong independent predictor of lung metastases. Compared with dogs with an easily separated localized tumour, dogs with a multiple/diffuse malignant CMT pattern had a fivefold higher risk of death. The risk of death was significantly higher in the presence of neoplastic emboli (~ fivefold) and tumour ulceration (~ fourfold). Furthermore, the presence of neoplastic emboli and large tumour size were independent predictors of CMT-related death.