Feline Facial Spindle Cell Tumors in 29 Cats: Histomorphological and Immunohistochemical Characterization.

Soft tissue tumors/sarcomas (STSs) in felines, encompassing a variety of mesenchymal tumors with similar histomorphological features, present diagnostic challenges due to their diverse cellular origins and the overlap with other tumor types such as feline sarcoid. This study aimed to delineate the clinical, histomorphological, and immunohistochemical characteristics of 34 feline facial spindle cell tumors affecting 29 cats, including testing for bovine papillomavirus type 14 (BPV14), the virus causing feline sarcoids. Only five out of 12 tumors previously diagnosed as feline sarcoids based on histomorphology were confirmed by PCR for BPV14, underscoring the importance of comprehensive diagnostic approaches to accurately distinguish between STSs and feline sarcoids. This study shows that most facial spindle cell tumors were compatible with peripheral nerve sheath tumors (PNSTs) based on positive immunohistochemical staining for Sox10 and other immunohistochemical markers such as GFAP, NSE, and S100. Some of these tumors displayed as multiple independent masses on the face or as erosive and ulcerative lesions without obvious mass formation, an atypical presentation and an important highlight for general practitioners, dermatologists, and oncologists. This study also describes periadnexal whorling of neoplastic cells as a novel histomorphologic finding in feline facial PNSTs and emphasizes Sox10 as a useful complementary immunohistochemical marker for the diagnosis of facial PNST in cats, providing valuable insights for veterinary pathologists.

Extensive staging has no prognostic value in dogs with low-risk mast cell tumours.

In canine mast cell tumours (MCTs), distant metastasis (DM) occurs infrequently. However, high-risk MCTs or tumours with certain negative prognostic factors (NPFs) are those more prone to develop metastatic disease. Accordingly, a thorough workup might not be necessary for MCTs lacking NPFs. The objective of this study was to evaluate the rate of DM and, therefore, the benefit of extensive staging in dogs presenting with and without NPFs. Furthermore, the association between the selected NPFs and DM was assessed, and factors that may have influenced outcome were evaluated. Dogs presenting with at least one NPF (Patnaik III/Kiupel high-grade, LN metastasis, rapid growth, ulceration, recurrence, high-risk location) were defined as high-risk and without as low-risk MCTs. Ninety-nine dogs were included, with 49% of MCTs in the high-risk and 51% in the low-risk group. All seven dogs with DM were identified in the high-risk group; 43% were Patnaik III/Kiupel high-grade tumours. The median survival time (MST) for this subgroup was 84 days. Patnaik III/Kiupel high-grade and rapid growth were NPFs significantly associated with DM at staging. Furthermore, a significant difference (p < .001) in MST was demonstrated between the high-risk and low-risk groups (899 days vs. not reached). NPFs significantly associated with outcome were rapid growth, presence of DM at staging, and surgical tumour excision. These results indicate that extensive staging in the absence of NPFs does not seem to be beneficial. On the other hand, by using the selected NPFs, a subset of MCTs prone to DM can be identified.

Maintenance treatment in relapsed canine lymphoma after a short L-CHOP protocol.

OBJECTIVE: A number of different rescue protocols for relapsed canine multicentric large-cell lymphoma have been described. The aim of this pilot study was to evaluate the efficacy of a maintenance treatment in dogs that experienced a second complete remission after a short L-CHOP-rescue protocol. MATERIAL AND METHODS: Included in the study were dogs experiencing the first lymphoma relapse during a treatment-free period which were treated with a short L-CHOP protocol, achieved a complete remission and were afterwards treated with a continuous maintenance phase (MP) protocol. The L-CHOP protocol consisted of weekly treatments, with at least 3 additional treatments following complete remission. Thereafter the MP protocol with 2-week treatment intervals was conducted. It consisted of alternating oral home administration of different alkylating agents and one intravenously administered cytotoxic agent of a different mechanism of action. The dogs were presented either every 4 or 6 weeks for intravenous treatment and at this time a complete blood count was performed. The durations of the first remission, disease-free interval and overall survival time were evaluated. RESULTS: A total of 20 dogs were included in the study. A median of 7 weekly applications were given before the treatment was switched to the MP protocol. During MP, 14 dogs were treated intravenously every 6 weeks and 6 dogs every 4 weeks. Haematological adverse events were mainly mild. During the L-CHOP-protocol, one septic event occurred, and 2 dogs were hospitalized due to gastrointestinal adverse events. No patient required hospitalization during the MP. Fifteen dogs completed at least one cycle in the MP and a median of 8.5 chemotherapeutic treatments were administered. The median disease-free interval was 264 days and the median overall survival time was 737 days. CONCLUSION AND CLINICAL RELEVANCE: The protocol was generally well tolerated. Since 5 patients showed disease progression during the first cycle of the MP, dogs should ideally be evaluated for minimal residual disease before being switched to the MP. The case number in the presented study was low and the treatment relatively heterogeneous. Therefore, more dogs have to be treated with the proposed protocol before general recommendations can be made.

Serum concentrations of IL-31 in dogs with nonpruritic mast cell tumours or lymphoma.

BACKGROUND: The aim of this study was to compare serum interleukin (IL)-31 concentrations in dogs with lymphoma and mast cell tumours (MCT) without pruritus to those of healthy dogs. HYPOTHESIS/OBJECTIVES: To determine if IL-31 plays a role in tumour pathogenesis and if IL-31 could be a biological marker for disease progression. ANIMALS: Forty-eight healthy dogs and 36 dogs with neoplasia [multicentric lymphoma (14), MCT (15) and cutaneous lymphoma (7)] were included in the study. METHODS AND MATERIALS: Dogs with neoplasia were assigned to three different groups. Group 1 consisted of patients with multicentric lymphoma, which were diagnosed by cytological, histopathological and clonality investigations. Thoracic radiographs, ultrasound examination of the abdominal cavity, and fine-needle aspirates from liver and spleen were used to determine the lymphoma stage Patients with cutaneous lymphoma, diagnosed by cytological and histopathological findings, were included in Group 2. Patients with MCT, diagnosed by cytological and histopathological findings, were included in Group 3. Serum was frozen at -80ºC before measuring the concentration of IL-31 via a Simoa ultra-sensitive, fully automated two-step immunoassay. RESULTS: Serum concentrations of IL-31, regardless of the disease and its staging, were within the normal range in all patients; there was no difference between any of the different tumour groups and healthy dogs. CONCLUSIONS AND CLINICAL IMPORTANCE: IL-31 is not likely to be involved in the pathogenesis of canine MCT or lymphoma without pruritus.

Nasal transmissible venereal tumours in 12 dogs - a retrospective study.

OBJECTIVE: The aim of this study was a retrospective analysis of clinical manifestation and treatment outcome of the nasal form of transmissible venereal tumours (TVT). MATERIAL AND METHODS: Twelve dogs suffering from nasal TVT were included in this study. Patients with primary genital lesions were excluded from the study. Signalment, physical examination and laboratory findings, results of further diagnostics, and treatment results were recorded in all patients. RESULTS: The study population comprised 9 male and 4 female dogs with an (estimated) age ranging from 3 to 7 years. With one exception all dogs originated from Ukraine. Symptoms of nasal TVT included sneezing, nasal bleeding (all cases), skull infiltration (9 cases), oronasal fistulas (9 cases) and cutaneous fistulas (5 cases). Animals received vincristine sulfate at 0.7 mg/m2 i. v. weekly. The treatment course consisted of 4-9 cycles (median 5 cycles). Complete remission was achieved in all cases. All dogs were disease-free during the follow-up period (median 23.5 months, range 12-56 months). All patients tolerated the treatment very well. CLINICAL SIGNIFICANCE: In conclusion, our data suggest that nasal TVT can have a good response to vincristine treatment. TVT should be considered as a differential diagnosis in sneezing dogs with nasal discharge or bleeding especially in young dogs and in dogs with suspected nasal tumours, even in countries without a stray animal population.