Immunohistochemical expression of vimentin, E-cadherin, and CD45 in natural cases of canine cutaneous round tumors.

Round cell tumors are common cutaneous lesions in dogs, with increased occurrence percentages among different skin tumors. This study aimed to investigate the frequency as well as gross and pathological characteristics of round cell tumors in natural cases of tumorous dogs in relation to breed, sex, and age. Moreover, it aimed to evaluate the immunohistochemical expression of a panel of immunohistochemical stains, including vimentin, E-cadherin, and cluster of differentiation (CD45) as an adjunct technique for the differential diagnosis of cutaneous round cell neoplasm. Data were collected from 64 dogs of both sexes (36 females and 28 males), various breeds, and different ages (8 months to 7 years). The histopathological nature of neoplastic growth was reported, and neoplasm prevalence was classified using age, sex, breed, and site on the body. We observed 48 cases of transmissible venereal tumors, 12 cutaneous histiocytomas, and 4 histiocytic sarcoma. Immunohistochemical characterization revealed an intense positive immunoreactivity for vimentin in transmissible venereal tumor cells and moderate positive immunoreactivity for E-cadherin and CD45 in cutaneous histiocytoma and histiocytic sarcoma cells. In conclusion, the canine transmissible venereal tumor was the most frequent form of round cell tumor; thus, a definitive cutaneous neoplasm diagnosis should be based on histopathological morphology and immunohistochemical findings.

Immunohistochemical evidence of NF-kB activation in canine lymphomas, histiocytic sarcomas, hemangiosarcomas, and mast cell tumors.

Increased or constitutive activation of nuclear factor kappa B (NF-kB) is a feature of many chronic disease processes, including cancer. While NF-kB overactivation has been documented extensively in human oncology, there is a relative paucity of data documenting the same phenomenon in veterinary medicine. To assess NF-kB activity, antibodies to p65 and p100/p52, which are components of NF-kB heterodimers, were first validated for specificity and canine cross-reactivity via Western blot and labeling of immortalized cell pellets. Then, nuclear labeling for these antibodies was assessed via QuPath software in over 200 tumor tissue samples (10 hemangiosarcomas, 94 histiocytic sarcomas, 71 lymphomas, and 28 mast cell tumors) and compared to immunolabeling in appropriate normal tissue counterparts. Greater than 70% of spontaneous canine tumors evaluated in this study had more nuclear p65 and p100/p52 immunoreactivity than was observed in comparable normal cell populations. Specifically, 144/204 (70.58%) of tumors evaluated had positive p65 nuclear labeling and 179/195 (91.79%) had positive p100/p52 nuclear labeling. Surprisingly, greater nuclear p100/p52 reactivity was associated with a longer progression-free survival (PFS) and overall survival (OS) in canine lymphomas. These results provide support and preliminary data to investigate the role of NF-kB signaling in different types of canine cancer.

Concomitant occurrence of multicentric hemangiosarcoma and histiocytic sarcoma in a dog

Histiocytic sarcoma (HS) is uncommon malignant neoplasia of round cells with marked predilection in Rottweiler and Bernese Mountain. The disseminated form, which mainly affects the spleen, lungs, lymph nodes, bone marrow, skin, and subcutis, presents a quick and aggressive clinical behavior. Hemangiosarcoma (HAS) is a malignant neoplasm of endothelial vessel cells commonly reported to affect the right atrium of dogs' hearts. A male Rottweiler, five years old, presented flaccid paraplegia and progressive muscular atrophy in the temporal, masseter, and limbs muscles; Due to the clinical stage of the animal, euthanasia was conducted. During the necroscopic examination, it was noticed that several masses presented different sizes; some were whitish, and others were reddish and spread in multiple organs (lungs, heart, spleen, stomach, kidneys, brain, medulla, skeletal muscle, and pre-scapular lymph node). Microscopically, in some organs such as the stomach, right ventricle, lungs, and medulla, it was noticed a proliferation of myeloid cells, highly cellular, with poor demarcation, no encapsulation, and with the infiltrative growth pattern of cells with high pleomorphism. Numerous tumoral emboli were observed in the spleen, brain, skeletal muscle, and lymph node. These cells were submitted for immunohistochemistry and were positive for CD18 (HS antibody). In the right atrium, liver, and kidney it was observed malignant and infiltrative endothelial proliferation (HSA) and emboli in the medulla. Therefore, we conclude that both neoplasms (HS and HSA) cause the animal's paraplegia due to their embolism and metastasis to the spinal cord and skeletal muscle.(AU)

Myeloid and histiocytic sarcomas in subantarctic fur seals Arctocephalus tropicalis, Brazil.

Histopathological and immunohistochemical methods were used to diagnose round cell tumors in 2 subantarctic fur seals Arctocephalus tropicalis with marked anemia. Although wild-born, both individuals were placed under human care while juveniles in a Brazilian aquarium. Both pinnipeds were PCR tested for herpesvirus, and 1 was infected with otariid gammaherpesvirus 5 (OtHV-5), previously described in a subantarctic fur seal stranded in Brazil. Although some gammaherpesviruses can cause sarcomas and other neoplasms, it was not possible to definitively associate OtHV-5 with the neoplasm. To our knowledge, these are the first neoplasm records in subantarctic fur seals.

Atypical spleen hemophagocytic histiocytic sarcoma in a dog

Background: The histiocytic sarcoma (HS) complex is a set of malignant neoplasms originating from interstitial dendritic cells or macrophages. When it involves macrophages of the splenic red pulp and bone marrow, it is referred to as hemophagocytic histiocytic sarcoma (HHS). HHS behaves more aggressively than HS and is usually fatal. HHS can be diagnosed by cytological and histopathological examination of neoplastic tissue. HHS is confirmed by immunohistochemistry using an anti-CD11d antibody. This neoplasm is often confused with immune-mediated hemolytic anemia or Evans syndrome due to erythrophagocytosis and platelet consumption. The clinical presentation of the animals progresses with evident anemia and thrombocytopenia, leading to signs such as prostration, inappetence, and pale mucosa, making diagnosis challenging and often late. This study aimed to report the clinic-pathological aspects of a canine with atypical hemophagocytic splenic HS. Case: A 4-year-old male Shih-Tzu canine was referred to the Veterinary Hospital with a history of prostration and anorexia. Pale mucous membranes were observed on physical examination. Blood tests revealed non-regenerative anemia, leukopenia, and thrombocytopenia. Serum protein levels were below the reference values for the species in biochemical examinations. Hemoparasitosis was suspected; however, the result of the polymerase chain reaction was negative. Abdominal ultrasound revealed a splenomegaly with heterogeneous parenchyma and a slightly irregular surface, but no visible mass in the spleen. Due to the difficulty of stabilizing the patient, even after successive transfusions, the animal underwent exploratory laparotomy with medial access and posterior splenectomy. Subsequently, the spleen was surgically removed, fixed in 10% buffered formalin, and processed routinely. Macroscopically, it had an irregular reddish-brown capsular surface. Histopathological examination of the spleen revealed a densely cellular neoplasm composed of round to spindle cells (histiocytes) arranged haphazardly in variably sized sheets separating the pre-existing spleen stroma. These histopathological findings were consistent with a histiocytic malignant neoplasm. Immunohistochemical analysis was performed to better define the origin of the histiocytic neoplasm. Neoplastic cells showed positive immunostaining of more than 80% of tumor cells for the CD11d antibody and weak immunostaining for CD11c and lysozyme. The patient survived for less than 30 days after the first hospital visit. Discussion: The diagnosis of HHS was based on the histological characteristics and positive immunostaining of more than 80% of the tumor cells for the CD11d antibody. HHS is an extremely aggressive and rare tumor that affects elderly dogs of any breed. In this study, HHS had atypical histologic characteristics, in which erythrophagocytosis and hemosiderin were not observed within macrophages. HHSs arise from macrophages of the red pulp of the spleen or bone marrow and express the b2 integrin, CD11d, and have low expression of CD1 and CD11c, which are predominantly expressed by non-hemophagocytic HS. The hematological and biochemical changes observed in this case were similar to those described in other dogs with HHS. Treatment of HHS is only palliative. Erlichia ewingii, E. canis, Anaplasma phagocytophilum, A. platys, Borrelia burgdorferi, Dirofilaria immitis, Leishmania infantum and immune-mediated hemolytic anemia are the main differential diagnoses because they cause anemia and thrombocytopenia accompanied by splenomegaly.

Hemophagocytic histiocytic sarcoma in dog

Background: Histiocytic sarcoma can present in a localized or disseminated form, being a malignant neoplasm derived from interstitial dendritic cells. Another form of the disease is called hemophagocytic histiocystic sarcoma (HHS), which originates from macrophages located in the splenic red pulp and bone marrow. HHS is a rare neoplasm with unknown etiology and rapid development. It mainly affects middle-aged to elderly animals. It primarily affects the spleen and bone marrow, with occurence of metastases in other organs. Some canine breeds are considered more predisposed to this neoplasia, among them the Rottweiler. The aim of this study was to report a case of HHS in a Rottweiler dog. Case: An 8-year-old Rottweiler suffering from hyporexia and progressive weight loss for a month was attended at the Veterinary Hospital of State University of Maringá. On physical examination, he only presented mild discomfort on abdominal palpation. Blood count was performed, which revealed mild thrombocytopenia (145,000/µL, reference value for the species 150,000-500,000/µL). The Polymerase Chain Reaction (PCR) exam was requested for babesiosis and ehrlichiosis, due to a history of ectoparasites. The animal was released with the prescription of Doxycycline at a dose of 10 mg/kg orally for 28 days. After 5 days, the condition worsened and the animal returned with emesis, apathy and hyporexia, being hospitalized. Abdominal ultrasound, blood count, urinalysis, serum urea and creatinine tests were requested. Among the hematological changes, thrombocytopenia (116,000/µL) and the appearing of regenerative anemia and atypical round cells with ample and slightly basophilic cytoplasm in the smear, similar to histiocytes, stood out. On ultrasound examination, splenomegaly was observed with hypoechogenic areas. Ultrasound-guided fine-needle aspiration cytology (FNAC) of the spleen was performed, which...(AU)

Hemophagocytic histiocytic sarcoma in dog

Background: Histiocytic sarcoma can present in a localized or disseminated form, being a malignant neoplasm derived from interstitial dendritic cells. Another form of the disease is called hemophagocytic histiocystic sarcoma (HHS), which originates from macrophages located in the splenic red pulp and bone marrow. HHS is a rare neoplasm with unknown etiology and rapid development. It mainly affects middle-aged to elderly animals. It primarily affects the spleen and bone marrow, with occurence of metastases in other organs. Some canine breeds are considered more predisposed to this neoplasia, among them the Rottweiler. The aim of this study was to report a case of HHS in a Rottweiler dog. Case: An 8-year-old Rottweiler suffering from hyporexia and progressive weight loss for a month was attended at the Veterinary Hospital of State University of Maringá. On physical examination, he only presented mild discomfort on abdominal palpation. Blood count was performed, which revealed mild thrombocytopenia (145,000/µL, reference value for the species 150,000-500,000/µL). The Polymerase Chain Reaction (PCR) exam was requested for babesiosis and ehrlichiosis, due to a history of ectoparasites. The animal was released with the prescription of Doxycycline at a dose of 10 mg/kg orally for 28 days. After 5 days, the condition worsened and the animal returned with emesis, apathy and hyporexia, being hospitalized. Abdominal ultrasound, blood count, urinalysis, serum urea and creatinine tests were requested. Among the hematological changes, thrombocytopenia (116,000/µL) and the appearing of regenerative anemia and atypical round cells with ample and slightly basophilic cytoplasm in the smear, similar to histiocytes, stood out. On ultrasound examination, splenomegaly was observed with hypoechogenic areas. Ultrasound-guided fine-needle aspiration cytology (FNAC) of the spleen was performed, which...

Disseminated histiocytic sarcoma in a Labrador retriever in Brazil

Histiocytic sarcoma (HS) refers to a rare neoplasm of round cells frequently presented in a disseminated form, affecting bones, joints, skin, and subcutaneous tissue. The objective of this study was to report a case of disseminated HS in a canine attended at HOVET-UFRPE, Recife, Brazil. Physical examination and complementary tests were performed; complete blood count and serum biochemistry were normal, but at thoracic radiography exam a neoformation was detected in the right lung. Cytopathological evaluation was suggestive of malignant epithelial neoplasia. At necropsy, there were disseminated nodules in the lungs, liver, spleen, kidneys, meninges and eye. The histopathological examination revealed proliferation of pleomorphic round cells, suggesting HS, which was confirmed by immunohistochemistry. From the obtained results, it becomes evident the importance of complementary exams to properly diagnose histiocytic diseases. This is one of the few reports of canine disseminated HS in Brazil.

Disseminated histiocytic sarcoma in a Labrador retriever in Brazil

Histiocytic sarcoma (HS) refers to a rare neoplasm of round cells frequently presented in a disseminated form, affecting bones, joints, skin, and subcutaneous tissue. The objective of this study was to report a case of disseminated HS in a canine attended at HOVET-UFRPE, Recife, Brazil. Physical examination and complementary tests were performed; complete blood count and serum biochemistry were normal, but at thoracic radiography exam a neoformation was detected in the right lung. Cytopathological evaluation was suggestive of malignant epithelial neoplasia. At necropsy, there were disseminated nodules in the lungs, liver, spleen, kidneys, meninges and eye. The histopathological examination revealed proliferation of pleomorphic round cells, suggesting HS, which was confirmed by immunohistochemistry. From the obtained results, it becomes evident the importance of complementary exams to properly diagnose histiocytic diseases. This is one of the few reports of canine disseminated HS in Brazil.(AU)

Risk Factors Associated with Development of Histiocytic Sarcoma in Bernese Mountain Dogs.

BACKGROUND: Histiocytic sarcoma (HS) is a rare but aggressive malignancy in humans that is poorly responsive to existing treatments. Although rare in most breeds of dogs, HS is common in Bernese mountain dogs (BMDs). OBJECTIVE: Determine risk factors associated with development of HS in BMD. ANIMALS: A total of 216 BMD were registered with the Berner-Garde Foundation. METHODS: An internet-based cross-sectional survey was used to collect information from owners of BMD diagnosed with HS and owners of disease-free littermates of dogs with HS. Mixed-effects logistic regression (MELR) and conditional logistic regression (CLR) were used in parallel to examine associations between potential risk factors and the occurrence of HS. RESULTS: When controlling for litter as a marker of relatedness, dogs diagnosed with orthopedic conditions were found to be more likely to develop HS (MELR, OR: 2.5, 95% CI: 1.5, 5.2; CLR, OR: 2.81, 95% CI: 1.1, 7.3), whereas dogs receiving prescription anti-inflammatory medications were found to be at considerably lower risk of developing HS (MELR, OR: 0.42, 95% CI: 0.2, 0.8; CLR, OR: 0.32, 95% CI: 0.1, 0.8). CONCLUSIONS AND CLINICAL IMPORTANCE: These results suggest inflammation may be a modifiable risk factor for the development of HS in BMD.

Histomorphological and immunohistochemical characterization of 172 cutaneous round cell tumours in dogs / Caracterização histomorfológica e imuno-histoquímica de 172 neoplasias cutâneas de células redondas em cães

This paper describes the use of a panel of antibodies (CD117, CD3, CD79a, CD45, cytokeratin, vimentin and E-cadherin) on formalin-fixed, paraffin-embedded sections of canine cutaneous round cell tumours. Neoplastic tumours were diagnosed by histology and histochemical stains and included 107 mast cell tumours, 31 cutaneous histiocytomas, two localized histiocytic sarcomas, 21 cutaneous lymphomas, three plasma cell tumours, one transmissible venereal tumour and seven unclassified round cell tumours. The histologic diagnosis was modified in 39.5% of the total 172 neoplasms. The staining for CD45 and Ecadherin were variable, and therefore, the final diagnoses of cutaneous histiocytoma and localized histiocytic sarcoma were made based on histology in association with negative results for CD3, CD79a, CD117 and cytokeratin. The cellular origin of unclassified round cell tumours was defined in all cases. Cutaneous B-cell lymphoma and plasma cell tumours were CD79a-positive and could be distinguished from each other by the morphological characteristics. Mast cell tumours and T cell lymphoma were CD117 and CD3 positive, respectively. The positive staining for vimentin and the negative staining for CD3, CD79a, CD117 and cytokeratin favoured the diagnosis of transmissible venereal tumours. Thus, the final diagnosis of cutaneous round cell tumours should be based on the interpretation of immunohistochemical results together with the cellular morphology observed by histology. Therefore, more studies to optimize the specific markers in formalin-fixed, paraffinembedded tissues (especially for histiocytes) are required for definitive diagnosis of round cell tumours in dogs.(AU)

Este trabalho descreve o uso de um painel de anticorpos (CD117, CD3, CD79a, CD45, citoqueratina, vimentina e e-caderina em tecidos formalizados e parafinizados para o diagnóstico de neoplasias de células redondas em cães. Os tumores foram diagnosticados usando-se a histopatologia e a marcação imuno-histoquímica. Foram incluídos 107 mastocitomas, 31 histiocitomas cutâneos, 2 sarcomas histiocíticos localizados, 21 linfomas cutâneos, 3 plasmocitomas, 1 tumor venéreo transmissível e 7 tumores de células redondas não classificados. O diagnóstico histológico foi modificado em 39,5% do total de 172 neoplasias. A marcação do anticorpo CD45 e E-caderina foi variável e, nesse sentido, o diagnóstico final de histiocitoma cutâneo e sarcoma histiocítico localizado foi baseado na histologia em associação com os resultados negativos para CD3, CD79a, CD117 e citoqueratina. A origem celular dos tumores de células redondas não classificados foi definida em todos os casos. Linfoma cutâneo de célula B e plasmocitoma foram positivos para CD79a e foram distinguidos entre si pelas características morfológicas. Marcação positiva para vimentina e negativa para CD3, CD79a, CD117 e citoqueratina favoreceram o diagnóstico dos tumores venereos transmissíveis. Assim, o diagnóstico final dos tumores de células redondas foram baseados na interpretação dos resultados da imuno-histoquímica em conjunto com a avaliação das características morfológicas observadas na histologia. Finalmente, mais estudos em relação à padronização de marcadores específicos para tecidos parafinizados (especialmente para histiócitos) são necessários para o diagnóstico definitivo das neoplasias de células redondas em cães.(AU)

Histomorphological and immunohistochemical characterization of 172 cutaneous round cell tumours in dogs / Caracterização histomorfológica e imuno-histoquímica de 172 neoplasias cutâneas de células redondas em cães

This paper describes the use of a panel of antibodies (CD117, CD3, CD79a, CD45, cytokeratin, vimentin and E-cadherin) on formalin-fixed, paraffin-embedded sections of canine cutaneous round cell tumours. Neoplastic tumours were diagnosed by histology and histochemical stains and included 107 mast cell tumours, 31 cutaneous histiocytomas, two localized histiocytic sarcomas, 21 cutaneous lymphomas, three plasma cell tumours, one transmissible venereal tumour and seven unclassified round cell tumours. The histologic diagnosis was modified in 39.5% of the total 172 neoplasms. The staining for CD45 and Ecadherin were variable, and therefore, the final diagnoses of cutaneous histiocytoma and localized histiocytic sarcoma were made based on histology in association with negative results for CD3, CD79a, CD117 and cytokeratin. The cellular origin of unclassified round cell tumours was defined in all cases. Cutaneous B-cell lymphoma and plasma cell tumours were CD79a-positive and could be distinguished from each other by the morphological characteristics. Mast cell tumours and T cell lymphoma were CD117 and CD3 positive, respectively. The positive staining for vimentin and the negative staining for CD3, CD79a, CD117 and cytokeratin favoured the diagnosis of transmissible venereal tumours. Thus, the final diagnosis of cutaneous round cell tumours should be based on the interpretation of immunohistochemical results together with the cellular morphology observed by histology. Therefore, more studies to optimize the specific markers in formalin-fixed, paraffinembedded tissues (especially for histiocytes) are required for definitive diagnosis of round cell tumours in dogs.

Este trabalho descreve o uso de um painel de anticorpos (CD117, CD3, CD79a, CD45, citoqueratina, vimentina e e-caderina em tecidos formalizados e parafinizados para o diagnóstico de neoplasias de células redondas em cães. Os tumores foram diagnosticados usando-se a histopatologia e a marcação imuno-histoquímica. Foram incluídos 107 mastocitomas, 31 histiocitomas cutâneos, 2 sarcomas histiocíticos localizados, 21 linfomas cutâneos, 3 plasmocitomas, 1 tumor venéreo transmissível e 7 tumores de células redondas não classificados. O diagnóstico histológico foi modificado em 39,5% do total de 172 neoplasias. A marcação do anticorpo CD45 e E-caderina foi variável e, nesse sentido, o diagnóstico final de histiocitoma cutâneo e sarcoma histiocítico localizado foi baseado na histologia em associação com os resultados negativos para CD3, CD79a, CD117 e citoqueratina. A origem celular dos tumores de células redondas não classificados foi definida em todos os casos. Linfoma cutâneo de célula B e plasmocitoma foram positivos para CD79a e foram distinguidos entre si pelas características morfológicas. Marcação positiva para vimentina e negativa para CD3, CD79a, CD117 e citoqueratina favoreceram o diagnóstico dos tumores venereos transmissíveis. Assim, o diagnóstico final dos tumores de células redondas foram baseados na interpretação dos resultados da imuno-histoquímica em conjunto com a avaliação das características morfológicas observadas na histologia. Finalmente, mais estudos em relação à padronização de marcadores específicos para tecidos parafinizados (especialmente para histiócitos) são necessários para o diagnóstico definitivo das neoplasias de células redondas em cães.

Histiocitose maligna sistêmica em um cão - Relato de caso / Malignant histiocystosis in a dog - Case report

A histiocitose maligna sistêmica é uma proliferação de histiócitos que acomete cães idosos de raças grandes e que geralmente ocorre na pele e vísceras. Os sinais clínicos variam e são inespecíficos. A quimioterapia prolonga a sobrevida do paciente, porém esta neoplasia tem alta taxa de metástase e prognóstico pobre. Este relato descreve um caso de histiocitose maligna sistêmica em um cão fêmea da raça Rottweiler, cuja evolução clínica foi rápida e com agravamento provocado pelas inúmeras metástases. Clinicamente o cão apresentou emagrecimento progressivo, dificuldade respiratória e nódulos ulcerados na pele. A radiografia torácica indicou múltiplos nódulos radiopacos pulmonares. A quimioterapia empregada não foi considerada eficaz. O animal apresentou progressão da doença e foi submetido à eutanásia. Foi realizada a necropsia tendo sido observado presença de nódulos na pele, pulmões, rins, cavidade abdominal e linfonodos. O exame histopatológico concluiu que se tratava dehistiocitose

Malignant histiocytosis is a proliferation of histiocitic cells occurring in older dogs of large breeds.Lesions may occur in the skin and internal organs. Clinical signs are unspecific. The clinical course of the disease is usually rapid and fatal. Chemotherapy may promote temporary remission and it could prolong survival time. This disease is highly metastatic and has a poor prognostic. The case of a female Rottweiler with malignant histiocytosis is reported in this paper. The systemic disease progressed rapidly. Clinically the dog showed weight loss, dyspnea and ulcerated skin lesions. There was evidence of multiple pulmonary nodules. The chemotherapy was not considered efficient. The dog developed progressive disease and was euthanized. At necropsy, the presence of nodules in skin, lungs, kidneys, abdominal cavity and lymph nodeswere observed

Histiocitose maligna sistêmica em um cão - Relato de caso / Malignant histiocystosis in a dog - Case report

A histiocitose maligna sistêmica é uma proliferação de histiócitos que acomete cães idosos de raças grandes e que geralmente ocorre na pele e vísceras. Os sinais clínicos variam e são inespecíficos. A quimioterapia prolonga a sobrevida do paciente, porém esta neoplasia tem alta taxa de metástase e prognóstico pobre. Este relato descreve um caso de histiocitose maligna sistêmica em um cão fêmea da raça Rottweiler, cuja evolução clínica foi rápida e com agravamento provocado pelas inúmeras metástases. Clinicamente o cão apresentou emagrecimento progressivo, dificuldade respiratória e nódulos ulcerados na pele. A radiografia torácica indicou múltiplos nódulos radiopacos pulmonares. A quimioterapia empregada não foi considerada eficaz. O animal apresentou progressão da doença e foi submetido à eutanásia. Foi realizada a necropsia tendo sido observado presença de nódulos na pele, pulmões, rins, cavidade abdominal e linfonodos. O exame histopatológico concluiu que se tratava dehistiocitose(AU)

Malignant histiocytosis is a proliferation of histiocitic cells occurring in older dogs of large breeds.Lesions may occur in the skin and internal organs. Clinical signs are unspecific. The clinical course of the disease is usually rapid and fatal. Chemotherapy may promote temporary remission and it could prolong survival time. This disease is highly metastatic and has a poor prognostic. The case of a female Rottweiler with malignant histiocytosis is reported in this paper. The systemic disease progressed rapidly. Clinically the dog showed weight loss, dyspnea and ulcerated skin lesions. There was evidence of multiple pulmonary nodules. The chemotherapy was not considered efficient. The dog developed progressive disease and was euthanized. At necropsy, the presence of nodules in skin, lungs, kidneys, abdominal cavity and lymph nodeswere observed(AU)

Malignant histiocytosis in a cat - Case report

A crossbred 14-year-old castrated male cat had a history of lethargy, anorexia and weight loss of one month evolution. On clinical examination, anemia, emaciation, jaundice and a large mass in the abdomen were detected. Ultrasonography revealed hepatomegaly and a single splenic mass. The cat was submitted to biopsy and euthanatized during the surgical procedure. The diagnosis of malignant histiocytosis was achieved on the basis of the clinical presentation, histopathologic and immunoistochemical findings.