Gastrointestinal stromal tumor (GIST) presenting as a multilocular cystic intra-abdominal mass in a dog

Background

Gastrointestinal stromal tumor (GIST) is a malignant mesenchymal neoplasm described in humans, dogs, and cats. A hallmark of diagnosis for GISTs is positive immunohistochemical labelling with c-Kit (CD117). The differentiation of GIST from other mesenchymal neoplasms of the gastrointestinal tract is pivotal to allow for initiation of appropriate treatment. In humans, cystic GIST has been described, though this has not been reported in dogs. In humans, the cystic form of GIST has been associated with a favorable prognosis. In the present paper, we report a case of multilocular cystic GIST in a dog, which has not previously been described in this species.

Case presentation

A ten-year-old, male-entire Maltese terrier mix breed dog presented with a large cystic mural mass of the duoedenum and orad jejunum. Histopathology and positive immunohistochemical staining with CD117 confirmed a diagnosis of GIST. No evidence of metastasis was detected on routine staging with abdominal sonography and thoracic radiography at the time of diagnosis. Surgical resection was performed and toceranib therapy was initiated post-operatively. Metastasis was documented 251 days after surgery on computed tomography. Due to clinical deterioration, the patient was humanely euthanised 370 days after surgical excision.

Conclusions

There are few differential diagnoses for large multilocular cystic intra-abdominal masses in dogs. This case presents a previously undescribed presentation of gastrointestinal stromal tumor in the dog as a predominantly multilocular cystic mass. It remains unclear if the cystic form of GIST may represent a favorable prognosis in dogs.

Mutational Analysis of c-KIT and PDGFRA in Canine Gastrointestinal Stromal Tumors (GISTs)

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the canine gastrointestinal tract and are diagnosed by the immunohistochemical expression of the receptor tyrosine kinase (RTK) KIT. Activating mutations of the proto-oncogenes c-KIT and PDGFRA drive GIST oncogenesis and are used to predict the response to RTK-inhibitors in human oncology. Currently, the frequency and significance of these mutations in canine GIST have not been adequately explored. Therefore, we investigated the mutational status of c-KIT (exons 9, 11 and 13) and PDGFRA (exons 12 and 18) genes by PCR followed by fragment analysis for c-KIT deletions and PCR followed by screening with DHPLC and direct sequencing confirmation for single nucleotide variations in 17 formalin-fixed paraffin-embedded canine GISTs confirmed by KIT immunopositivity. c-KIT mutations were detected in 47% of cases, with a mutation detection rate significantly higher (p = 0.0004, Fisher’s exact test) and always involving exon 11. A PDGFRA gene mutation (exon 18) was identified in one case. Even if follow-up data were not available for all cases, four cases with documented abdominal metastases displayed c-KIT mutations. These data confirm that c-KIT exon 11 mutations occur frequently in canine GISTs, and identify the presence of a PDGFRA mutation similar to human GISTs. This study also suggests a potential association of c-KIT mutation with more aggressive biological behavior.

Retrospective immunohistochemical investigation of suspected non-visceral leiomyosarcoma in dogs

Visceral leiomyosarcoma is well described in dogs, but information about non-visceral locations and prevalence is lacking. The diagnosis of leiomyosarcoma is challenging without a gold standard, and often includes the use of immunohistochemical (IHC) stains. We used defined histopathologic patterns, histochemical staining, and IHC staining for smooth muscle actin (SMA), desmin, and laminin to characterize suspected non-visceral leiomyosarcoma in dogs at a single academic institution. In a retrospective search, we identified 24 dogs with a definitive or suspected histologic diagnosis of leiomyosarcoma in a non-visceral location. Histopathology results and clinical details were obtained. Biopsy sections were reviewed by a single pathologist using standardized histologic criteria, including light microscopic appearance, immunohistochemistry (more than two-thirds of neoplastic cells labeled with SMA and desmin or laminin), and histochemical staining (minimal-to-mild matrix deposition by Masson trichrome). Of the 24 cases of possible non-visceral leiomyosarcomas, 4 were consistent with a definitive diagnosis of non-visceral leiomyosarcoma (3) or leiomyoma (1) based on the established criteria. Only the leiomyoma had more than two-thirds of neoplastic cells label with all 3 markers; all 3 leiomyosarcomas had more than two-thirds of neoplastic cells label with SMA and laminin. Our data highlight the uncommon nature of non-visceral leiomyosarcoma and the importance of IHC for their diagnosis. A definitive diagnosis could not be made based on SMA alone, and desmin was not useful in this cohort. Further studies are needed to clarify the histopathologic, IHC, and clinical features of canine non-visceral SMA-positive mesenchymal tumors.

Role of ANO1 in tumors and tumor immunity

Dysregulation of gene amplification, cell-signaling-pathway transduction, epigenetic and transcriptional regulation, and protein interactions drives tumor-cell proliferation and invasion, while ion channels also play an important role in the generation and development of tumor cells. Overexpression of Ca²⁺-activated Cl- channel anoctamin 1 (ANO1) is shown in numerous cancer types and correlates with poor prognosis. However, the mechanisms involved in ANO1-mediated malignant cellular transformation and the role of ANO1 in tumor immunity remain unknown. In this review, we discuss recent studies to determine the role of ANO1 in tumorigenesis and provide novel insights into the role of ANO1 in the context of tumor immunity. Furthermore, we analyze the roles and potential mechanisms of ANO1 in different types of cancers, and provide novel notions for the role of ANO1 in the tumor microenvironment and for potential use of ANO1 in clinical applications. Our review shows that ANO1 is involved in tumor immunity and microenvironment, and may, therefore, be an effective biomarker and therapeutic drug target.

Incidental diagnosis of a spindle cell type gastrointestinal stromal tumor in a dog with ethylene glycol intoxication

A 6-year-old castrated male American Pit Bull Terrier dog was presented for evaluation of acute onset of tonic-clonic seizures, anorexia, and vomiting. On physical examination, neurologic signs, such as generalized proprioceptive ataxia, salivation, circling to the right, and absent patellar reflexes bilaterally, were noted. A complete blood cell count revealed mild hemoconcentration and an inflammatory leukogram, while a chemistry panel showed severe azotemia, marked hypochloremia, and a severe titrational metabolic acidosis, suggesting possible ethylene glycol intoxication. However, an irregularly round, small mass was identified in the large intestine on abdominal ultrasound. Additionally, bilateral hyperechoic renal cortices with medullary rim sign were suggestive of acute nephritis or tubular necrosis. The cytologic evaluation of a fine-needle aspiration biopsy of the abdominal mass revealed a large population of mesenchymal cells, suggesting the presence of neoplasia. Due to the worsening of symptoms, the dog was humanely euthanized. Necropsy confirmed ethylene glycol intoxication, and the incidental finding of a neoplastic intestinal mass was diagnosed as spindle cell sarcoma. Immunohistochemical staining showed strong, diffuse positivity for CD117, smooth muscle actin, and S-100, indicating the final diagnosis of a spindle cell type gastrointestinal stromal tumor (GIST). This report briefly discusses the classifications of nonlymphoid, nonangiogenic intestinal mesenchymal tumors, characteristics of GISTs, and the importance of the immunohistochemical classification of mesenchymal tumors of the gastrointestinal tract.

Needle rinse cell blocks as an ancillary technique: Diagnostic and clinical utility in gastrointestinal neoplasia

BACKGROUND

Fine-needle aspirate (FNA) cytology is often the first-choice method for diagnosing gastrointestinal nodular lesions. The FNA material can be converted to histopathology specimens by a needle rinse cell block (NRCB) technique, allowing ancillary studies to refine the cytologic diagnosis. Despite use in human pathology, NRCB has never been applied to canine or feline gastrointestinal neoplasia.

OBJECTIVE

This study described NRCB methodology and its diagnostic utility in specific cases of neoplastic gastrointestinal lesions.

METHODS

Needle rinses with saline were performed after ultrasound-guided FNAs of two intestinal lymphomas (canine and feline) and a canine gastrointestinal stromal tumor (GIST). The NRCB was prepared using the cell tube block technique and processed for paraffin embedding. Routine immunohistochemistry protocols (using CD3, PAX-5, and Ki-67 for lymphoma cases and vimentin, desmin, S-100, and KIT markers for GIST) were applied to NRCB sections, and the results were compared with matched tissue biopsies.

RESULTS

NRCBs with adequate cell numbers, preservation, and good separation of blood were obtained. The diagnosis and immunophenotyping were confirmed in both cases of lymphoma in NRCBs. In the GIST, the immunolabeling of the neoplastic cells in NRCB was completely concordant with the tissue biopsy.

CONCLUSIONS

The described methodology is suitable for veterinary settings, having few technical requirements and low invasiveness. The presented cases of gastrointestinal neoplasia highlight the utility of NRCBs as a platform to conduct ancillary studies and refine the cytologic diagnosis.

A narrative review of imatinib-resistant gastrointestinal stromal tumors

Objective:

Review the studies that investigate the mechanisms underlying imatinib-resistant gastrointestinal stromal tumors (GIST).

Background:

GIST are the most common mesenchymal tumors of the gastrointestinal (GI) tract and the most common sarcoma in humans. GIST are thought to be arise from interstitial cells of Cajal (ICC), pacemaker and neuromodulator cells in the GI tract, as well as “fibroblast”-like cells, which are another type of interstitial cells of the gut wall and also known as telocyte or platelet-derived growth factor-alpha (PDGFRA)-positive cells. The majority of GIST harbor gain-of-function mutations in either KIT or PDGFRA, and these gain-of-function mutations are mutually exclusive and most often heterozygous. GIST are responsive to the KIT/PDGFRA tyrosine kinase inhibitor (TKI), imatinib, the standard first-line drug for advanced and metastatic GIST. However, imatinib alone does not eradicate GIST despite an initial clinical benefit, and more than 90% of GIST harbor imatinib-resistance. Although second and third-generation TKIs have been developed and are currently in clinical use, they are not curative for refractory and metastatic GIST due to the emergence of clones with drug-resistant mutations. Eradication of drug-resistant GIST will cure patients with refractory GIST. Several mechanisms may contribute to refractory GIST. These mechanisms are secondary mutations in KIT and/or PDGFRA, alternative activation of tyrosine kinases, stem cells for GIST and cellular quiescence, a reversible nonproliferating state in which cells retain the ability to reenter cell proliferation.

Methods:

We review our current optimal treatment approach for managing patients with advanced and refractory GIST.

Conclusions:

This review explores the novel and potential therapeutic approaches to combat drug-resistant GIST.

Comparison of effusion cell block and biopsy immunohistochemistry in mesothelial hyperplasia, mesothelioma, and carcinoma in dogs

BACKGROUND

Determining the cause of effusions is challenging and might require a biopsy. Whether cell blocks from effusions are representative of biopsies requires investigation. A previously developed immunohistochemical panel aids in the differentiation of hyperplastic and neoplastic mesothelium in canine biopsies but has not been investigated in effusions.

OBJECTIVES

The study aimed to assess cell blocks as an alternative to biopsies and determine whether immunohistochemistry helps distinguish hyperplastic mesothelium, mesothelioma, and carcinoma.

METHODS

Effusions and biopsies were collected from five dogs with mesothelial hyperplasia (group MH), six with mesothelioma (group M), and five with carcinoma (group C). Immunohistochemistry (IHC) for cytokeratin, vimentin, Wilm's tumor protein 1 (WT1), desmin, glucose transporter 1 (GLUT1), and insulin-like growth factor II mRNA-binding protein 3 (IMP3) was performed. Sections were scored for staining intensity and the percentage of positively stained cells.

RESULTS

In paired cell blocks and biopsies, vimentin and WT1 staining were positively correlated for intensity and the percentage of positive cells, although not all paired results were identical. The intensity of IMP3 staining in cell blocks was higher in group M than in group C (P = 0.012), and WT1 staining was higher in group MH than in group C (P = 0.020). For biopsies, the intensity of WT1 staining was higher in group MH than in group C (P = 0.031). In group C, WT1 was negative in all cell blocks and biopsies, and desmin was negative in four of five cases.

CONCLUSIONS

IHC results for the cell blocks and biopsies were comparable for potentially useful markers, such as WT1, which helped discriminate between groups. IHC provided additional information, although results were not always definitive. Further studies on a larger population are required.

Prognostic factors for dogs with surgically resected gastrointestinal stromal tumors

Few reports have investigated prognosis of canine gastrointestinal stromal tumor (GIST) cases treated by surgical resection alone. In the present study, we investigated the overall survival (OS) and prognostic factors for dogs with GIST treated by surgical complete resection alone. Fifty-three dogs were included, and the median OS was 18 months. Multivariate analysis showed that primary tumors in small intestine (P=0.04) is significantly associated with shorter OS, and median OS of the cases with cecum lesion and those with small intestine lesion was 22 and 6 months, respectively. The present study suggested primary tumor site was a novel prognostic factor for dogs with GIST treated by surgical complete resection alone.

Outcome, prognostic factors and histological characterization of canine gastrointestinal sarcomas

Canine gastrointestinal sarcomas, a group of tumours that includes leiomyosarcomas (LMSAs), gastrointestinal stromal tumours (GISTs) and other rarer sarcomas, comprise about 10-30% of all gastrointestinal tumours. This study aims to characterize the histologic characteristics and clinical behaviour in order to identify prognostic factors predictive of outcome. A single institution database search for surgically treated gastrointestinal sarcomas yielded 47 cases with adequate tissue remaining for histologic analysis and 42 cases available for analysis of clinical outcome. Tumours were then prospectively evaluated for mitotic count, necrosis, haemorrhage and inflammation, as well as categorized via immunohistochemical (IHC) staining for smooth muscle actin, c-KIT and DOG-1. IHC analysis defined 32 tumours as GISTs, 14 as LMSAs and one as a sarcoma not otherwise specified. For both GISTs and LMSAs, the overall median survival time (MST) is 1024 days (range 31-1456), which did not differ statistically between tumour types (p = .92). The overall metastatic rate of GISTs in this study was 32.1% (n = 9) which was not significantly different to that of LMSAs at 15.3% (n = 2, p = .45). In multivariate analysis, mitotic count under 9 in GIST patients and complete surgical excision in all tumour types correlated with improved MST. For patients with GISTs, the intensity of c-KIT staining also correlated positively with survival, with an MST of 250 days in cases with weak staining and an MST of 1418 days in cases with moderate or strong c-KIT staining (p = .005).

Detection of ANO1 mRNA in PBMCs is a promising method for GISTs diagnosis

ANO1 is a calcium-activated chloride channel protein that has been used to diagnose GISTs after tissue biopsy. Recently, ANO1 mRNA amplification in the blood has received considerable attention as a useful method for the diagnosis of GISTs. The aim of this study was to evaluate the diagnostic ability of ANO1 mRNA in distinguishing GIST patients from healthy subjects. We constructed a logistic regression model for examining the diagnostic ability of ANO1 mRNA in comparison with conventional tumor markers, including CEA, CA199, and CA724. Our results showed that ANO1 mRNA was significantly amplified in PBMCs, the average expression level and range of ANO1 mRNA in the blood were increased along with the expression of ANO1 in the tissues, and the extent of amplification of ANO1 was associated with tumor size. In addition, ROC curve analysis showed that ANO1 mRNA in the blood had the highest specificity when compared with conventional tumor markers. Moreover, a combined analysis with ANO1 mRNA and conventional tumor markers had the highest sensitivity in diagnosing GISTs. Our study indicated that detection of ANO1 mRNA in PBMCs is a promising method for diagnosis of GISTs in vitro.

Retrospective evaluation of toceranib phosphate (Palladia®) use in the treatment of gastrointestinal stromal tumors of dogs

Background

Gastrointestinal stromal tumors (GISTs) are uncommon intestinal neoplasms in the dog. Literature regarding adjunctive therapy for GISTs in dogs is sparse. High‐risk GISTs in humans respond to tyrosine kinase inhibition in the adjuvant setting.

Objectives

To review cases of toceranib phosphate use in dogs with GISTs and provide initial assessment of possible biological activity. A secondary aim was to evaluate patient and tumor characteristics for possible prognostic value.

Animals

Twenty‐seven dogs with confirmed GISTs based on histopathology and immunohistochemistry treated with toceranib.

Methods

Retrospective study in which cases of toceranib use in dogs with GIST were solicited using the American College of Veterinary Internal Medicine Oncology and Small Animal Internal Medicine listservs.

Results

Five of 7 dogs with gross disease experienced clinical benefit (71%; 3 complete responses, 1 partial response, 1 stable disease). These included 2 dogs with durable responses after toceranib discontinuation. Median progression‐free interval (PFI) in dogs with gross disease was 110 weeks (range, 36‐155 weeks). Median PFI in dogs with microscopic disease was 67 weeks (range, 9‐257 weeks). Metastasis at diagnosis (P = 0.04) and high mitotic index (P < 0.001) were associated with shorter PFI in toceranib‐treated dogs.

Conclusions and Clinical Importance

Biological activity of toceranib is evident in dogs with gross disease. Metastasis of GIST at diagnosis, as well as high tumor mitotic index, was associated with shorter PFI in toceranib‐treated dogs. Larger studies are needed to define postsurgical risk and refine the use of toceranib in dogs with gross and microscopic GIST.

Canine sarcomas as a surrogate for the human disease

Pet dogs are becoming increasingly recognized as a population with the potential to inform medical research through their treatment for a variety of maladies by veterinary health professionals. This is the basis of the One Health initiative, supporting the idea of collaboration between human and animal health researchers and clinicians to study spontaneous disease processes and treatment in animals to inform human health. Cancer is a major health burden in pet dogs, accounting for approximately 30% of deaths across breeds. As such, pet dogs with cancer are becoming increasingly recognized as a resource for studying the pharmacology and therapeutic potential of anticancer drugs and therapies under development. This was recently highlighted by a National Academy of Medicine Workshop on Comparative Oncology that took place in mid-2015 (http://www.nap.edu/21830). One component of cancer burden in dogs is their significantly higher incidence of sarcomas as compared to humans. This increased incidence led to canine osteosarcoma being an important component in the development of surgical approaches for osteosarcoma in children. Included in this review of sarcomas in dogs is a description of the incidence, pathology, molecular characteristics and previous translational therapeutic studies associated with these tumors. An understanding of the patho-physiological and molecular characteristics of these naturally occurring canine sarcomas holds great promise for effective incorporation into drug development schemas, for evaluation of target modulation or other pharmacodynamic measures associated with therapeutic response. These data could serve to supplement other preclinical data and bolster clinical investigations in tumor types for which there is a paucity of human patients for clinical trials.

Tumor estromal gastrointestinal em cães: estudo clínico-anatomopatológico

RESUMO Os tumores estromais gastrointestinais (GIST) são incomuns e apresentam elevada similaridade histológica com as neoplasias de músculo liso e de nervo periférico. Este trabalho relata e caracteriza GIST em cães do ponto de vista epidemiológico, clínico-laboratorial, anatomopatológico e imuno-histoquímico, com base na análise retrospectiva de três cães, machos, com média de idade de 10 anos, variando de porte médio a grande e peso médio de 18.5±6kg. As alterações clínicas foram progressivas e inespecíficas de quadro gastrointestinal crônico, tais como prostração, anorexia, perda de peso e melena. Anemia não regenerativa e leucocitose foram os principais achados laboratoriais. Macroscopicamente, os tumores apresentavam média de 19cm no eixo maior, localizados em jejuno e ceco, com a superfície ulcerada, e exibiam áreas de necrose. Na avaliação microscópica, os casos apresentaram proliferação de células fusiformes, arranjadas em feixes longos densamente celulares, que foram vimentina e CD117 positivas, com diferenciação neural (S100 positivo), muscular (actina e desmina positivas) e anaplásica, cuja morfologia caracteriza neoplasias malignas com sobrevida de um dia a 12 meses. O GIST deve ser um dos diagnósticos diferenciais a serem considerados entre as neoplasias mesenquimais do trato gastrointestinal que acometem cães, e o diagnóstico final necessita de imuno-histoquímica.

Circulating tumor cells as a prognostic and predictive marker in gastrointestinal stromal tumors: a prospective study

BACKGROUND

Circulating tumor cells (CTC) are prognostic and predictive for several cancer types. Only limited data exist regarding prognostic or predictive impact of CTC on gastrointestinal stromal tumor (GIST) patients. The aim of our study was to elucidate the role of CTC in GIST patients.

RESULTS

A total of 121 GIST patients and 54 non-GIST samples were enrolled in the study. The cutoff value for ANO1 positive was 3*10-5 and 65 (54%) GIST patients were defined as ANO1 positive. ANO1s were more frequently detected in unresectable patients. Tumor size, mitotic count and risk level were associated with ANO1 detection in resectable GIST patients. The presence of ANO1 significantly correlated with poor disease-free survival (15.3 versus 19.6 months, p = 0.038). Most patients turned ANO1-negative after surgery and inversely, all 21 patients with recurrence turned ANO1-positive with high ANO1 expression levels. Moreover, in the neoadjuvant setting, decline of ANO1 expression level correlated with the response of imatinib.

METHODS

Cells from peripheral blood mononuclear cells tested positive for anoctamin 1, calcium activated chloride channel, ANO1 (DOG1) were considered as tumor CTC of GISTs. The expression levels of ANO1 were determined using quantitative real-time polymerase chain reaction (qRT-PCR). The highest level of ANO1 expression in non-GIST samples was used as the "cutoff" value.

CONCLUSION

ANO1 detection by qRT-PCR in peripheral blood is of clinical potential for monitoring recurrence and evaluating therapeutic efficacy of imatinib for GIST patients.

Canine Gastric Pathology: A Review

Gastric disorders are common in dogs and are a major reason for veterinary consultation. In human medicine, the classification of gastric diseases based on histological features, genotypes and molecular phenotypes helps to better understand the characteristics of each subtype, and to improve early diagnosis, prevention and treatment. Canine gastric lesions often show strong histological similarities to their human counterparts. However, such conditions in the canine stomach are poorly studied and their cellular and molecular features are largely unknown. This article reviews the histopathological classification of inflammatory and neoplastic lesions of the canine stomach and provides an update on the application of molecular techniques within the field of canine gastric pathology. The canine disorders are compared with current knowledge of the equivalent human diseases.