Mitotic activity: A systematic literature review of the assessment methodology and prognostic value in feline tumors

Increased proliferation is a driver of tumorigenesis, and quantification of mitotic activity is a standard task for prognostication. This systematic review is an analysis of all available references on mitotic activity in feline tumors to provide an overview of the assessment methods and prognostic value. A systematic literature search in PubMed and Scopus and a nonsystematic search in Google Scholar were conducted. All articles on feline tumors that correlated mitotic activity with patient outcome were identified. Data analysis revealed that of the 42 eligible articles, mitotic count (MC, mitotic figures/tumor area) was evaluated in 39 studies, and mitotic index (MI, mitotic figures/tumor cells) in 3 studies. The risk of bias was considered high for most studies (26/42, 62%) based on small study populations, insufficient details of the MC/MI methods, and lack of statistical measures for diagnostic accuracy or effect on outcome. The MC/MI methods varied between studies. A significant association of MC with survival was determined in 20 of 28 (71%) studies (10 studies evaluated other outcome metrics or provided individual patient data), while 1 study found an inverse effect. Three tumor types had at least 4 studies, and a prognostic association with survival was found in 5 of 6 studies on mast cell tumors, 5 of 5 on mammary tumors, and 3 of 4 on soft-tissue sarcomas. MI was shown to correlate with survival for mammary tumors by 2 research groups; however, comparisons to MC were not conducted. Further studies with standardized mitotic activity methods and appropriate statistical analysis for discriminant ability of patient outcome are needed to infer the prognostic value of MC and MI.

Feline ventral abdominal wall angiosarcoma: haemangiosarcoma or lymphangiosarcoma? Clinical and pathological characteristics in nine cases

OBJECTIVES

Angiosarcomas are rare malignant mesenchymal neoplasms of endothelial cell origin with a predilection to the ventral abdominal wall in cats. Larger case series describing this entity are lacking.

METHODS

Two referral centre laboratory databases were searched for angiosarcoma of the ventral abdominal wall. Nine cases with a histological diagnosis were included. Immunohistochemistry (factor VIII and PROX-1 antibodies) was used to phenotype them as haemangiosarcoma or lymphangiosarcoma.

RESULTS

All cats presented with a ventral abdominal mass, five of which were producing a serosanguinous discharge. Eight underwent tumour staging and pulmonary metastases were suspected in one cat (but not histologically confirmed). With histopathology alone, a diagnosis of angiosarcoma and lymphangiosarcoma was made in four and five cases, respectively. After immunohistochemistry, five cases had a haemangiosarcoma phenotype and four had a lymphangiosarcoma phenotype, including two cases of lymphangiosarcoma that were reclassified as hemangiosarcoma. Eight cats received treatment (either surgery with or without adjuvant therapies or medical management alone). Six cats were euthanased due to local disease progression. The median survival time for haemangiosarcoma was 166 days (range 137-381), and for lymphangiosarcoma it was 197 days (range 67-208). Two cats with haemangiosarcoma remained alive for a follow-up period of 329 and 580 days, respectively.

CONCLUSIONS AND RELEVANCE

Feline ventral abdominal angiosarcomas are rare locally aggressive neoplasms. While histology often provides a diagnosis of angiosarcoma, immunohistochemistry is ultimately required to differentiate between haemangiosarcoma and lymphangiosarcoma phenotypes. Further studies are required to evaluate whether the different phenotypes have an impact on treatment response and outcome.

Urinary bladder hemangiosarcoma in a cat treated with partial cystectomy and adjuvant metronomic cyclophosphamide and thalidomide

Visceral hemangiosarcomas (HSA) are rare in cats and typically associated with aggressive biologic behavior and poor prognosis. A 4-year-old male neutered domestic shorthair cat was presented with a 3-month history of hematuria and stranguria; ultrasonography identified a large bladder mass. Complete excision was achieved by partial cystectomy. Histopathology and immunohistochemistry for von Willebrand factor confirmed HSA. The cat was treated using adjuvant cyclophosphamide, thalidomide, and meloxicam for 8 months. Abdominal ultrasonography repeated at 2 months and computed tomography repeated at 5 and 19 months after diagnosis showed no evidence of local recurrence or metastasis. The cat was alive at last follow-up (896 days). Although the cat described in this report experienced a more favorable prognosis compared to other visceral HSA locations, additional cases are needed to further understand the biological behavior of bladder HSAs and guide treatment decisions.

Histopathological Results of Mouth Lesions in Dogs and Cats from Colombia

Mouth-related neoplastic and non-neoplastic lesions are commonly found in dogs and cats, and their diagnosis and classification are important for treatment planning and prognosis. This retrospective study analyzed mouth-related lesions in dogs and cats between 2000-2019 from the animal pathology laboratory of the Universidad de Antioquia, Medellín, Colombia. A total of 640 mouth-related lesions affecting 572 dogs (89.4%) and 68 cats (10.6%) were reviewed. Lesions were classified as neoplastic or non-neoplastic. The average age for neoplastic lesions was 8.6 years in dogs and 6.4 years in cats, while for non-neoplastic lesions the average age was 7.7 years for dogs and 5 years for cats. Data was analyzed using descriptive statistical methods according to year and source of report, demographic information for the animal, location of the lesion, and diagnosis. Tissue origin and behavior were variables considered for neoplastic lesions. Melanoma was the most common neoplasia in dogs and squamous cell carcinoma was most common in cats. The most frequent non-neoplastic lesion in dogs was gingival hyperplasia, while in cats the inflammatory lesions showed a wide range of morphological diagnoses. This study described many pathological lesions affecting the oral cavity for both dogs and cats and provides useful epidemiological data for both pathologists and clinicians.

Hemorrhage and Sudden Death in a Cat with Pancreatic Hemangiosarcoma

A 15-year-old female, indoor, spayed, domestic shorthair cat was presented for post-mortem evaluation with a history of sudden death. A red-brown 3 cm x 4 cm neoplastic mass was identified within the body of the pancreas, along with multiple similar nodular structures within the omentum and liver. Associated lesions included hemoperitoneum, yellow discoloration of the peritoneal wall, and severe anemia. Spindle-shaped neoplastic cells exhibiting malignancy features, which occasionally contained within the cytoplasm haematoidin crystals and/or red blood cells, were observed during cytological examination. Histologically, the neoplastic cells were organized in short streams forming vascular spaces filled with erythrocytes. Immunohistochemically, the neoplastic cells were immunolabeled for vimentin and CD31, supporting the diagnosis of hemangiosarcoma. This report offers a complete post-mortem and histological evaluation of a rare tumor in cats with an unusual location and a comparative assessment of 3 anti-CD31 antibodies.

Hemangiosarcoma of the nasal planum in cats: five cases (2010-2021)

CASE SERIES SUMMARY

Nasal planum tumors are rare in cats, with squamous cell carcinoma over-represented. Other skin tumors have been reported in this location and though hemangiosarcoma frequently occurs on the skin of the head, these tumors localized to the nasal planum have not been specifically reported. The objectives of this study were to report the clinical findings and outcomes in cats diagnosed with hemangiosarcoma of the nasal planum. Medical records from four different institutions were reviewed to identify cats with a definitive diagnosis of hemangiosarcoma of the nasal planum. Five cats met the inclusion criteria. One cat was treated with palliative radiation therapy (RT) alone, two cats had lesions removed via an excisional biopsy by the primary care veterinarian and two cats had excisional biopsies performed at a referral institution. All four cats that received surgical treatment were treated with adjuvant strontium-90 therapy. The cat receiving palliative RT alone was lost to follow-up 311 days after treatment. At the time of writing, the survival time for 2/3 cats receiving surgery and strontium-90 was 365 days and 1381 days, respectively. One cat receiving this combination of therapy was lost to follow-up immediately after treatment. One cat developed tumor recurrence and a revision surgery via nasal planectomy and upper lip resection was performed 376 days following the initial surgery. Following revision, palliative RT was pursued. The cat was still alive at the time of writing 618 days after the initial procedure, with no evidence of recurrence.

RELEVANCE AND NOVEL INFORMATION

In this case series, surgery was the primary treatment used, but due to the location, only narrow or incomplete surgical margins were possible. RT (strontium-90 and/or palliative) was utilized to decrease the risk of recurrence.

Use of doxorubicin chemotherapy following debulking surgery in the treatment of a cat with mesenteric hemangiosarcoma

Case summary

A 7-year-old male castrated domestic shorthair cat presented with a 5-day history of inappetence. A mid-abdominal mass was palpated and, on exploratory laparotomy, a cystic mass arising from the root of the mesentery was observed. The mass was drained, debulked and omentalized. Histopathologic examination and immunohistochemistry supported a diagnosis of hemangiosarcoma. Adjuvant doxorubicin was started and, prior to the third of five doses of doxorubicin, repeat abdominal ultrasound showed complete response of the primary tumor. Continued monitoring 240 days following histopathologic diagnosis revealed suspected metastasis to local lymph nodes, though the primary tumor remained absent on abdominal ultrasound. A second course of five doses of doxorubicin chemotherapy was completed. Serial abdominal ultrasounds demonstrated stable disease in the locoregional lymph nodes with no visible recurrence of the primary tumor. The cat presented 430 days following diagnosis with lethargy and inappetence. Abdominal ultrasound revealed suspected metastatic mesenteric and ileocolic lymphadenopathy, hepatic metastasis and peritoneal effusion, and the owner elected for humane euthanasia. Necropsy findings and negative immunohistochemical staining for lymphatic vessel endothelial receptor-1 were consistent with a metastatic mesenteric hemangiosarcoma.

Relevance and novel information

Hemangiosarcoma is an uncommon malignancy in cats, and few cases describing treatment have been reported. To our knowledge, this is the first report to describe the use of debulking surgery and adjuvant doxorubicin chemotherapy in the treatment of mesenteric hemangiosarcoma resulting in extended survival in a cat. Multimodal therapy can be considered for the management of cats with mesenteric hemangiosarcoma.

Extravascular papillary endothelial hyperplasia mimicking soft tissue sarcoma in 2 cats: a potential diagnostic pitfall

Papillary endothelial hyperplasia (PEH) is a rare soft tissue lesion arising from excessive reactive endothelial cell proliferation described in humans, dogs, and horses. PEH is considered a diagnostic challenge in humans, in which it is frequently misdiagnosed as angiosarcoma. We describe here PEH that developed at injection sites in 2 cats that were initially misdiagnosed as feline injection-site sarcoma by cytology and as subcutaneous angiosarcoma by histopathology. Morphologic features included sharp demarcation from surrounding tissues, and a layered microscopic architecture with an outer fibrous capsule from which emerged fibrovascular stalks covered by a monolayer of factor VIII-related antigen and CD31-positive flat-to-plump endothelial cells. Both lesions had a cystic core containing abundant erythrocytes and fibrin. PEH lesions did not recur in either case. Immunohistochemistry for α-smooth muscle actin and desmin demonstrated that the capsule was devoid of smooth muscle cells, excluding an intravascular origin. PEH in these cats was hypothesized to have developed extravascularly following trauma related to injection. We wish to provide awareness of PEH in domestic cats and of the risk of misdiagnoses leading to overtreatment.

Hemangiosarcoma cells induce M2 polarization and PD-L1 expression in macrophages

Hemangiosarcoma (HSA) is a malignant tumor derived from endothelial cells. Tumor-associated macrophages are one of the major components of tumor microenvironment and crucial for cancer development. The presence and function of macrophages in HSA have not been studied because there is no syngeneic model for HSA. In this study, we evaluated two mouse HSA cell lines and one immortalized mouse endothelial cell line for their usefulness as syngeneic models for canine HSA. Our results showed that the ISOS-1 cell line developed tumors with similar morphology to canine HSA. ISOS-1 cells highly expressed KDM2B and had similar KDM2B target expression patterns with canine HSA. Moreover, we determined that in both ISOS-1 and canine HSA tumors, macrophages were present as a major constituent of the tumor microenvironment. These macrophages were positive for CD204, an M2 macrophage marker, and express PD-L1, an immune checkpoint molecule. Canine HSA with macrophages expressing PD-L1 had a smaller number of T-cells in tumor tissues than tumors with PD-L1 negative macrophages. ISOS-1-conditioned medium could induce M2 polarization and PD-L1 expression in RAW264.7 mouse macrophage cell line and mouse peritoneal macrophages. These results show that ISOS-1 can be used as a syngenic model for canine HSA and suggest that macrophages play an important role in immune evasion in HSA. Using the syngeneic mouse model for canine HSA, we can further study the role of immune cells in the pathology of HSA.

Auricular Non-Epithelial Tumors with Solar Elastosis in Cats: A Possible UV-Induced Pathogenesis

The photoinduced etiopathology of actinic keratosis and squamous cell carcinoma in feline species is well known. This etiology has also been reported for non-epithelial cutaneous tumors in other species. To date, no cases of auricular non-epithelial cutaneous neoplasms erased in a contest of actinic keratosis in cats have been reported. The aim of this study was to describe feline auricular non-epithelial cutaneous neoplasms associated with typical UV-induced cutaneous lesions and solar elastosis. The study was conducted on five feline cases diagnosed with auricular non-epithelial cutaneous tumors (two fibrosarcomas, one mixosarcoma, one epithelioid melanoma and one hemangiosarcoma), selected from the Tumor Registry of the Department of Veterinary Sciences of the University of Pisa (1998–2018). Ten and six feline auricular biopsies of normal skin and skin with actinic keratosis, respectively, were used as controls. Orcein stain was used to investigate solar elastosis. Histological changes related to chronic solar irradiation were documented in the skin adjacent to the neoplastic lesions in the five cats. Considering the anatomical localization and the results of histopathology, this study suggests that non-epithelial cutaneous neoplasms may have a UV-induced etiopathogenesis in the feline species.

Primary Uterine Hemangiosarcoma in a Thoroughbred: A Case Report

A 1.8-year-old maiden Thoroughbred filly, without previous history of mating or reproductive management, was referred for clinical inspection due to the presence of sanguineous vaginal discharge and severe abdominal pain. Transrectal palpation indicated uterine asymmetry, and transrectal ultrasonography revealed a mass near the cervix measuring 8.3 cm in diameter, with heterogeneous echogenicity, a trabeculated center, and a well-defined hyperechoic border. Smaller masses surrounded the larger uterine mass. During the examination, the mare expelled a uterine mass through the vulva. Histological and immunohistochemical (CD31 and Factor VIII) examinations of the expelled mass suggested a diagnosis of hemangiosarcoma. Therefore, a therapeutic hysterectomy was performed, and examinations of the uterine tissue confirmed the diagnosis. However, the mare was euthanized 2 weeks later due to postoperative complications. The animal was subjected to necropsy, and intestinal adhesions in the surgical incision were diagnosed as postoperative complications. No other neoplasms were found during necropsy, establishing the primary origin of the tumor. This case study presents the first known report of uterine hemangiosarcoma in an equine species.

Canine and feline haemangiosarcoma

INTRODUCTION

Haemangiosarcoma (HSA) is a malignant neoplasm of dogs and cats that is suspected to originate from a pluripotent bone marrow progenitor with a complex and multifactorial pathogenesis.

APPROACH

Pertinent literature was identified, reviewed, and summarized for inclusion in the manuscript.

RESULTS/INTERPRETATION

Dogs are more frequently diagnosed with HSA than cats, and primary sites of this disease include dermal, subcutaneous/intramuscular, and visceral (most commonly the spleen). Dogs and cats with HSA generally have a poor prognosis owing to the rapid and widespread metastasis typically associated with this disease. However, some forms such as cutaneous HSA behave in a less aggressive fashion with improved outcomes. Surgical excision and anthracycline-based chemotherapy remain the mainstays of treatment, although novel treatment modalities are currently under investigation for potential roles in treatment of this disease.

CONCLUSION

This review aims to describe the clinical presentation and progression of the various forms of HSA in dogs and cats as well as to provide a systematic review of the veterinary literature with a focus on the various published treatment options and associated outcomes.

Comparison of the oncogenomic landscape of canine and feline hemangiosarcoma shows novel parallels with human angiosarcoma

Angiosarcoma (AS) is a highly aggressive tumor of blood and lymphatic vessels in humans that shares many similarities with spontaneously occurring hemangiosarcoma (HSA) in dogs and cats. To investigate the genetic suitability of HSA as a model for AS, we sequenced ∼1000 cancer genes in 41 cases of HSA and matched germline tissue: 15 canine visceral HSAs, 13 canine skin HSAs and 13 feline skin HSAs. Analysis of visceral HSAs from dogs presenting with concurrent splenic and cardiac neoplasms showed that the tumors were not independent primaries, consistent with the highly metastatic nature of HSA. Comparison of HSA to AS revealed that several driver genes were recurrently mutated in both species, such as TP53, PIK3CA, ATRX, GRIN2A and LRP1B. Similar to AS, a UV mutational signature was found in a subset of canine cutaneous HSAs and both species show differing mutational profiles between tissue sites. Our characterization of canine and feline HSA demonstrates many important parallels to AS and provides hope that future studies on these cancers will benefit of all three species.

Recurrent corneal hemangiosarcoma in a cat with subsequent extension into the orbit

A 7-year-old neutered female Domestic Short-haired cat was presented for evaluation of ulceration and severe vascularization of the left cornea. Ophthalmic examination revealed a large red irregular mass over the whole cornea in the left eye. A lamellar keratectomy was performed. Histopathology revealed a chronic lymphoplasmacytic, histocytic, neutrophilic ulcerative keratitis with fibrosis and vascularization. The tumor recurred within 3 months, and another lamellar keratectomy and sclerotomy were performed. The lesion was diagnosed histopathologically as a hemangiosarcoma with incomplete margins. The mass recurred locally 6 weeks later, and an enucleation was performed. Histopathology revealed infiltration of the limbus and connective tissue beyond the sclera. Seven weeks later, a fluctuant swelling was found in the left orbit. Computed tomography confirmed a soft tissue attenuating mass measuring 33 x 24 mm diameter in the orbit. There was no sign of metastasis. Clinical remission was achieved with combined chemotherapy with doxorubicin and radiation therapy. The patient remained in clinical remission 20 months post-chemotherapy.

Aural Hematoma Secondary to Hemangiosarcoma in a Domestic Cat-Case Report

A 7-year-old, white, domestic short hair, female cat was presented with an aural hematoma of the right pinna, which had been partially resected a year previously. A 3 × 4 cm mass, macroscopically similar to an auricular hematoma, was visible on the convex surface and a smaller vascular lesion was present on the ear margin. Cytological examination of the smaller mass was suggestive of hemangiosarcoma, and a diagnosis confirmed by histopathologic and immunohistochemical tests. Complete pinnectomy with a wide margin was performed and during the 3-year follow-up, the cat had no local recurrence or metastasis. We conclude that hemangiosarcoma should be considered as a potential differential diagnosis in white-coated cats with an unusual clinical presentation of aural hematoma.

Use of metronomic chemotherapy in the management of a cat with abdominal haemangiosarcoma

CASE SUMMARY

A 12-year-old entire domestic shorthair was evaluated for a 5 week history of intermittent vomiting, loss of appetite and weight loss. Abdominal ultrasound revealed a multi-lobulated heterogeneous mass adjacent to the mesenteric vessels. Cytology from fine-needle aspirates was non-diagnostic. Histopathology from a Tru-cut biopsy was consistent with haemangiosarcoma. The cat was treated with metronomic chemotherapy using oral cyclophosphamide. The cat remained clinically well and was euthanased 10 months after diagnosis owing to development of a haemoabdomen.

RELEVANCE AND NOVEL INFORMATION

Prognosis of feline abdominal haemangiosarcoma is generally poor and limited information on treatment is available in the veterinary literature. The use of metronomic chemotherapy with oral cyclophosphamide in this cat provided a 10 month period of good-quality life.

Cutaneous Hemangiosarcoma in a Pacific Parrotlet (Forpus coelestis)

A 2-month-old Pacific parrotlet (Forpus coelestis) was presented for assessment following a traumatic injury to the right wing that resulted in persistent swelling and inflammation. Six weeks postinjury the bird underwent surgical resection of a large hemorrhagic cavitated mass that had formed at the site of the original injury and a second, smaller mass on the body in direct contact with the wing mass. Histopathology of the wing mass confirmed a diagnosis of hemangiosarcoma. While commonly diagnosed in domestic species, hemangiosarcoma is uncommonly reported in avian species. To the authors' knowledge, this is the first report of hemangiosarcoma in a Pacific parrotlet and describes the development of hemangiosarcoma in a psittacine bird following trauma-induced inflammation.

MULTICENTRIC T-CELL LYMPHOMA AND CUTANEOUS HEMANGIOSARCOMA IN A CAPTIVE CHEETAH (ACINONYX JUBATUS)

A 13-yr-old intact male cheetah (Acinonyx jubatus) presented for evaluation after a 4-mo history of intermittent lethargy and increased expiratory effort. The clinical signs were initially noted after the diagnosis and death of its 13-yr-old male sibling with solitary hepatic T-cell lymphoma. Physical examination findings included thin body condition, harsh lung sounds, peripheral lymphadenopathy, and a cutaneous mass on the right medial tarsus and scrotum. Excisional biopsies diagnosed well-differentiated cutaneous hemangiosarcomas. Thoracic radiographs revealed a cranial mediastinal mass. Complete blood count and serum biochemical analyses showed a leukocytosis with persistent lymphocytosis, progressive azotemia, and markedly elevated alkaline phosphatase. Because of the cheetah's declining quality of life, euthanasia was elected. Postmortem examination, histopathology, and immunohistochemical staining revealed multicentric T-cell lymphoma. Feline leukemia virus (FeLV) enzyme-linked immunosorbent assay, FeLV polymerase chain reaction (whole blood), and viral metagenomic analysis were negative. This is the first case of cutaneous hemangiosarcoma and multicentric T-cell lymphoma reported in a FeLV-negative cheetah.

Primary cranial mediastinal hemangiosarcoma in a young dog

Primary cranial mediastinal hemangiosarcomas are uncommon tumors. A 30-kg, 2-year-old, intact female German shepherd was presented for evaluation of cachexia and respiratory distress of a few days’ duration. Lateral radiographic projection of the thorax revealed significant pleural effusion. Computed tomography revealed a cranial mediastinal mass effect adjacent to the heart. On surgical exploration, a pedunculated mass attached to the esophagus, trachea, brachiocephalic trunk, left subclavian artery and cranial vena cava without attachment to the right atrium and auricular appendage was removed and debrided by use of blunt dissection and dry gauzes, respectively. Histopathology results described the cranial mediastinal mass as hemangiosarcoma. At 8 months and 5 days post-operatively, the patient died. Primary cranial mediastinal hemangiosarcomas, although a seemingly rare cause of thoracic pathology in young dogs, should be considered in the differential diagnosis for pleural effusion and soft tissue mass effect in the cranial mediastinum. This is the first case report in a dog to describe primary cranial mediastinal hemangiosarcoma.

Histology and Clinical Outcome of Benign and Malignant Vascular Lesions Primary to Feline Cervical Lymph Nodes

A novel form of primary feline hemangiosarcoma and additional cases of plexiform vascularization in the cervical lymph nodes are reported. Sixteen cases of feline lymphadenopathy attributed to abnormal vascular proliferation were identified and evaluated. Most of these lesions were diagnosed histologically as hemangiosarcoma. However, lesions of plexiform vascularization, with and without areas of putative malignant transformation, were also identified. Mean age of the cats was 11 years (range, 3–16 years) with most being domestic shorthair and medium hair (13). Two domestic long hair and 1 Maine Coon were identified. Excisional nodal biopsy was performed in 15 cases and incisional biopsy in 1 case. Six cats were euthanized due to their disease. Survival times ranged from ≤1 month to ≥30 months. We provide a new clinical differential for cervical lymphadenopathy in cats that is not widely recognized. Proper identification of primary nodal vascular lesions in cats will enable further characterization of clinical features and biologic behavior to determine specific therapy.

Laparoscopic splenectomy: operative technique and outcome in three cats

CLINICAL SUMMARY: The clinical findings, treatment and outcome for three cats that underwent laparoscopic splenectomy using bipolar vessel-sealing devices for resection of diffuse splenic disease are described. In each case, a three-portal laparoscopic technique was used. The spleen was manipulated and its mesentery and associated vessels sequentially cauterized and ligated to enable removal through a portal incision with minimal hemorrhage. Each of the three patients recovered from anesthesia without incident and was able to be discharged to the owner the next day. PRACTICAL SIGNIFICANCE: Laparoscopic splenectomy may be a safe and effective alternative to celiotomy in a select group of cats requiring splenectomy.

Comparison of CD34, CD31, and factor VIII-related antigen immunohistochemical expression in feline vascular neoplasms and CD34 expression in feline nonvascular neoplasms

The diagnosis of vascular neoplasms is often facilitated by the use of immunohistochemical markers such as factor VIII-related antigen, CD31, and CD34. However, the relative sensitivity and specificity of these markers have not been compared in cat vascular neoplasms. In this study, these 3 immunohistochemical markers were evaluated in 61 endothelial neoplasms (50 hemangiosarcomas and 11 hemangiomas) in 59 cats. All neoplasms were labeled by all 3 markers. CD34 had the highest average immunolabeling intensity in neoplastic endothelial cells. CD31 had the lowest average background labeling, followed by CD34 and factor VIII-related antigen, respectively. CD34 expression was also examined in 130 nonvascular neoplasms of cats; 14 of 62 epithelial neoplasms, 39 of 43 mesenchymal neoplasms, 8 of 23 leukocytic neoplasms, and 2 of 2 melanomas were positive. Given the broad expression of CD34 in mesenchymal neoplasms, this marker has limited diagnostic relevance for vascular neoplasms of cats.

Musculoskeletal neoplasia: an important differential for lumps or lameness in the cat

PRACTICAL RELEVANCE

Musculoskeletal neoplasia is an uncommon but Important differential diagnosis for cats presenting with lameness, pain or swellings associated with bones and/or soft tissues. The most common tumours of soft tissue origin are the sarcomas (in particular feline injection site sarcomas [FISSs]); the most common bone tumour of the cat is osteosarcoma (OSA).

CLINICAL CHALLENGES

FISSs present a clinical challenge in terms of their local invasiveness, difficulty in obtaining complete surgical excision and high risk of local recurrence. Axial and extraskeletal OSAs pose similar challenges, whereas appendicular OSA is usually easy to remove via limb amputation and can, therefore, carry a good prognosis in many cases.

PATIENT GROUP

Cats of any age, gender or breed may be affected, although bone tumours predominantly affect middle- to old-aged cats.

GLOBAL IMPORTANCE

Vaccination of cats is of global importance in preventing feline diseases; hence, any possible significant consequences of vaccination such as neoplasia, even of a low incidence, are of huge concern to cat owners and veterinarians alike.

EVIDENCE BASE

This review is based on current literature relating to pathogenesis, pathology, presentation, diagnosis, staging, treatment and prognosis. It aims to summarise feline musculoskeletal neoplasia for clinicians in general practice.

Mesenteric Vascular Thrombosis Associated with Disseminated Abdominal Visceral Hemangiosarcoma in a Cat

An adult castrated male cat was evaluated because of a 4 day history of lethargy and partial anorexia. Physical examination revealed abdominal pain with a palpable fluid wave. Cytologic and biochemical analyses of peritoneal effusion were suggestive of septic peritonitis. On surgical exploration of the abdomen, the mesenteric vessels had no palpable pulses and they contained gross thromboses. The intestines were white with no visible peristalsis. Necropsy findings included disseminated, poorly differentiated hemangiosarcoma throughout the abdomen. Mesenteric arterioles contained fibrin thrombi. To the author's knowledge, no previous reports exist of complete mesenteric vascular thrombosis associated with disseminated abdominal visceral hemangiosarcoma in a cat.

Epithelioid haemangiosarcoma in the ocular tissue of horses

Haemangiosarcomas (HSAs) are malignant tumours of endothelial cell origin. Epithelioid HSA is a variant of the histologically conventional HSA that has little or no morphological evidence of a vascular origin and has been reported rarely in domestic animals. The following report documents six cases of equine epithelioid HSA occurring in the ocular tissues of horses with a mean age of 19.8 years at the time of diagnosis. Microscopically, all of the lesions consisted of solid sheets or cords of epithelioid cells with rare narrow clefts or small spaces containing erythrocytes that were often the only feature indicating a vascular origin. On immunohistochemistry, the neoplastic cells expressed vimentin, CD31 and factor VIII-related antigen, but not cytokeratin, indicating an endothelial nature.

Outcome following splenectomy in cats

No studies have yet examined whether there are prognostic factors for survival for cats undergoing splenectomies. The medical records of 19 cats that had complete splenectomy were reviewed for information on preoperative, intraoperative, and postoperative factors. The most common presenting signs were a palpable abdominal mass in 58% and anorexia in 47% of the cats. Mast cell tumors were the most common reason for splenectomy and were found in 10/19 cats (53%); followed by hemangiosarcoma in 4/19 (21%); and lymphoma in 2/19 (11%). The Kaplan-Meier median survival time (MST) was 197 days, with a range from 2 days to 1959 days. Three cats were noted to have preoperative weight loss, and this was the only factor that had prognostic significance for survival following surgery. For cats with weight loss the MST was 3 days, for cats with no weight loss noted the MST was 293 days (P=0.008).