Ocular melanoma and mammary mucinous carcinoma in an African lion

  • Didier Q Cagnini1Email author,

    Affiliated with

    • Breno S Salgado2, 3,

      Affiliated with

      • Juliana L Linardi1,

        Affiliated with

        • Fabrizio Grandi2, 4,

          Affiliated with

          • Rafael M Rocha5,

            Affiliated with

            • Noeme S Rocha1, 2,

              Affiliated with

              • Carlos R Teixeira1,

                Affiliated with

                • Fabio Del Piero6 and

                  Affiliated with

                  • Julio L Sequeira2

                    Affiliated with

                    BMC Veterinary Research20128:176

                    DOI: 10.1186/1746-6148-8-176

                    Received: 19 July 2011

                    Accepted: 22 September 2012

                    Published: 25 September 2012

                    Abstract

                    Background

                    Reports of neoplasms in Panthera species are increasing, but they are still an uncommon cause of disease and death in captive wild felids. The presence of two or more primary tumor in large felids is rarely reported, and there are no documented cases of ocular melanoma and mammary mucinous carcinoma in African lions.

                    Case presentation

                    An ocular melanoma and a mammary mucinous carcinoma are described in an African lion (Panthera leo). The first tumour was histologically characterized by the presence of epithelioid and fusiform melanocytes, while the latter was composed of mucus-producing cells with an epithelial phenotype that contained periodic acid-Schiff (PAS) and Alcian blue staining mucins. Metastases of both tumor were identified in various organs and indirect immunohistochemistry was used to characterize them. Peribiliary cysts were observed in the liver.

                    Conclusions

                    This is the first description of these tumor in African lions.

                    Keywords

                    Panthera leo Ocular neoplasms Mammary gland Melanocytic neoplasms Peribiliary cysts

                    Background

                    Reports of neoplasms in Panthera species are increasing, particularly due to the increase in longevity of captive animals as well as the increased use of ultrasound, routine physical examinations, complete blood counts, blood chemistries, diagnostic biopsies and necropsies. Various neoplasms have been reported in captive lions. These include cutaneous tumor such as basal cell epithelioma [1], mast cell tumor [2], and subcutaneous fibrosarcoma [3]. There are also reports of other neoplasms such as oligodendroglioma [4], mucoepidermoid carcinoma of the salivary gland [5], gastric carcinoma [6], mammary carcinoma with ductular differentiation [7], lymphoma [8], intestinal adenocarcinoma with peritoneal carcinomatosis [9], and gall bladder carcinomas [10]. Recently, peribiliary cysts were also recognized in African lions [11, 12].

                    The presence of two or more primary tumor in wild felids has rarely been reported [13, 14] and there are no documented cases of ocular melanoma and mammary mucinous carcinoma in African lions. This report describes the clinical, histological, and immunohistochemical features of an ocular melanoma of the anterior chamber and of a spontaneous mammary mucinous carcinoma in an African lion (Panthera leo).

                    Case presentation

                    A 19-year-old captive ovariohysterectomized female African lion from a zoological park in Brazil was presented at the Veterinary Hospital of the São Paulo State University, Botucatu, Brazil, with the suspicion of an intraocular neoplasm with liver metastasis. Conjunctival hyperemia, moderate serous epiphora, buphthalmia and presence of an intraocular mass were detected in the left eye. Additionally, the lioness had a history of progressive weight loss, regurgitation, vomiting, and chronic fatigue. Biochemical analysis revealed an increase in alkaline phosphatase [145.8 IU/L; Reference: 0–96 IU/L], gamma glutamyltransferase [42.4 IU/L; Reference: 0–17 IU/L], and alanine aminotransferase [246.2 IU/L; Reference: 0–195 IU/L]. Reference values were based on the ISIS species value references [15]. Hematologic parameters (PCV, RBC, WBC, hemoglobin, mean cell hemoglobin concentration and serum total protein) were within normal limits.

                    Ocular enucleation was performed and the ocular globe was submitted for histological evaluation to the Veterinary Pathology Service of the same institution. Grossly, a firm, mottled black to white mass, measuring 1.5 cm in diameter infiltrated the anterior uvea filling approximately 30% of the anterior chamber. Tissue samples were collected, fixed in 10% neutral buffered formalin and sent for histopathological examination. Four-μm-thick sections were stained with haematoxylin and eosin and were histologically evaluated. The mass was composed of solid sheets of oval to epithelioid cells supported by scant fibrovascular stroma. The cells had moderate amounts of cytoplasm and indistinct cell borders. There was scattered intracytoplasmic melanin pigmentation that sometimes obliterated the cellular features. The majority of the cells presented oval nuclei with coarse stippled chromatin and an irregular and single nucleolus. Moderate anisocytosis and anisokaryosis were seen and there were approximately 3 mitotic figures per high power field. No atypical mitoses were observed. The morphologic features examined lead to a diagnosis of intraocular melanoma.

                    An abdominal ultrasound examination revealed multiple anechoic areas surrounded by thin hyperechoic structures interpreted as capsules surrounding cavitary areas. Hypoechoic nodules were also observed. Liver samples were then obtained by ultrasound-guided fine-needle aspiration for cytopathologic evaluation. Direct smears were prepared and stained with Giemsa (Merck, Darmstadt, Germany). Cytologically, there were hepatocytes containing intracytoplasmic lipid droplets indicating hepatic lipidosis, which was expected given the age of the lioness. During the liver fine-needle aspiration biopsy, a subcutaneous enlargement in the region of the right inguinal mammary gland measuring 7 × 3 cm was noted. Samples for cytopathologic evaluation were obtained by fine-needle aspiration of the mass and the cell morphology was suggestive of a mammary carcinoma.

                    Given the deterioration of the lioness’ clinical condition characterized by cachexia, the animal was euthanatized 2 months after the initial diagnosis of the mammary neoplasm, and was presented at the Veterinary Pathology Service of the same institution for post-mortem examination. At necropsy, an encapsulated subcutaneous lobular mass in the mammary region, measuring 25 × 13 × 5 cm was observed. On cut surface, the tumor was moderately firm, mottled white to yellow, and contained multifocal cysts measuring from 0.4 to 2 cm in diameter. Inguinal lymph nodes were enlarged measuring 2 × 9 × 3 cm, and presented multifocal lesions similar to the mammary nodule on cut surface. No additional cutaneous or subcutaneous masses were observed.

                    The liver had multifocal to coalescing cystic areas and masses (Figure 1). The cysts measured from 0.5 to 12 cm in diameter and contained a translucent fluid. Masses were moderately firm, white to yellow, measured from 2 to 12 cm in diameter, and had multifocal petechiae and ecchymoses on cut surface.
                    http://static-content.springer.com/image/art%3A10.1186%2F1746-6148-8-176/MediaObjects/12917_2011_500_Fig1_HTML.jpg
                    Figure 1

                    Cystic (arrow) and solid formations (arrowheads) can be observed in the liver.

                    Tumor similar to the mammary and liver masses were observed in the lungs and pleura and measured 1–4 cm. No other abnormalities were observed.

                    Samples were collected and processed for histologic examination. Microscopically, the mammary neoplasm was composed of clusters of cuboidal epithelial cells surrounded by a robust fibrovascular stroma separating the tissue in lobules. The cells presented moderate amounts of cytoplasm with indistinct cell borders, oval nuclei with a coarse stippled chromatin and multiple prominent nucleoli (Figure 2). Occasional cells with signet-ring appearance could be observed. There were small lakes of basophilic to eosinophilic proteinaceous material and multifocal necrosis of neoplastic tissue (Figure 2).
                    http://static-content.springer.com/image/art%3A10.1186%2F1746-6148-8-176/MediaObjects/12917_2011_500_Fig2_HTML.jpg
                    Figure 2

                    Basophilic to amphophilic extracellular mucus and slightly eosinophilic intracellular mucus can be observed in the mammary neoplasm. Hematoxylin and eosin (bar = 50 μm).

                    The histochemical features of the fluid were assessed by PAS, PAS-diastase, and alcian blue pH 2.5 stains. Intestinal and bronchial mucosal tissues from domestic cat and lion were used as positive controls for mucin. In the present case, PAS, with and without diastase, and alcian blue pH 2.5 positive mucins were observed within cells and stroma. Based on gross and histologic examination, the tumor was considered to be a spontaneous mammary mucinous carcinoma.

                    The liver contained solid neoplastic areas composed of medium size round to larger epithelioid oval cells with abundant cytoplasm, vesicular nuclei, and single prominent nucleoli supported by a fibrovascular stroma. Intracytoplasmic melanin was detected in a few neoplastic cells. Sections of the cystic areas had single layers of epithelial cells surrounded by fibrous connective tissue and were primarily located around the portal areas and were interpreted as peribiliary cysts. Lungs and pleura contained metastatic foci histologically similar to the primary mammary and ocular neoplasms.

                    To characterize the primary neoplasms and the metastatic foci, 3 μm serial sections were obtained and used for indirect immunohistochemistry. Antigen retrieval was performed by heat treatment in 10 mM citrate buffer, pH 6.0 for all primary antibodies. A polymeric labeling system kit (NovoLink Polymer Detection System, Novocastra Laboratories, Newcastle, UK) was used for peroxidase and protein blockages and detection of antigen-antibody reactions in all slides. Slides were incubated overnight at 4°C with specific primary antibodies. The primary antibodies used consisted of monoclonal antibodies against cytokeratin (Dako, clone AE1/AE3, diluted 1: 500), cytokeratin 19 (LabVision, clone BA17, diluted 1:400), α-smooth muscle actin (Santa Cruz Biotechnologies, clone 1A4, diluted 1:1200), vimentin (Dako, clone V9, diluted 1:2000), and melan A (Dako, clone M7196, diluted 1:50). Sections of normal domestic cat, lion mammary gland were used as positive controls for all antibodies except melan A, for which a canine cutaneous melanoma and domestic cat, lion pigmented skin were used. For negative control purposes the primary antibody was replaced by non-immune rabbit IgG (Dako). The slides were immersed with the detection system following the manufacturer’s instructions and 3,3’ diaminobenzidine tetrahydrochloride was used as chromogen in order to allow the visualization of antigen-antibody reaction. The slides were then counterstained using Harris’s hematoxylin, dehydrated, and mounted for evaluation via light microscopy.

                    The intraocular neoplastic cells expressed vimentin and Melan A, while cytokeratin, cytokeratin 19, and α-smooth muscle actin were not expressed. This immunophenotype indicated melanoma. The mucin-producing cells of the mammary tumor had an epithelial phenotype with cytokeratin 19 expression in the membrane and cytoplasm. These cells were also strongly vimentin positive (including mucin-producing cells) and mildly α-smooth muscle actin positive. Nonmucin-producing mammary cells were also detected and expressed cytokeratin 19, vimentin and α-smooth muscle actin. Stromal cells expressed vimentin and were negative for cytokeratin 19 and α-smooth muscle actin and were interpreted as fibroblasts. Given the immunohistochemical results, the mammary tumor was characterized mucinous carcinoma.

                    Metastatic foci in the lungs were also assessed using immunohistochemistry. Epithelial cuboidal cell clusters immersed in a mucinous stroma expressed cytokeratin, cytokeratin 19 and vimentin, an immunohistochemical profile consistent with mammary cells. In contrast, areas with epithelioid single cells expressed vimentin and Melan A, indicating melanoma cells. This indicated the presence of both mammary and melanoma pulmonary metastases. Multifocal melanoma liver metastases were identified by lack of expression of cytokeratin, cytokeratin 19 and the expression of Melan A and vimentin (Figure 3).
                    http://static-content.springer.com/image/art%3A10.1186%2F1746-6148-8-176/MediaObjects/12917_2011_500_Fig3_HTML.jpg
                    Figure 3

                    Melanoma cells expressing vimentin obliterating the liver architecture. DAB indirect immunohistochemistry, Harris hematoxylin counterstain (bar = 50 μm).

                    The presence of two or more primary tumor in wild felids is rarely reported. Multiple myeloma, adrenocortical carcinoma, and pheochromocytoma in a Jaguar (Panthera onca) [13], seminoma and parathyroid adenoma in a Snow leopard (Panthera uncia) [14], and mammary carcinoma and leiomyosarcoma in a Jaguar [16] were previously documented. There are no reports of multiple neoplasms in African lions (Panthera leo). Additionally, there are no documented cases of simultaneous and isolated occurrence of ocular melanoma and mammary mucinous carcinoma in these animals.

                    Tumor of melanocytic origin are the most common primary intraocular neoplasms of cats [17]. Ocular melanomas are tumor that tend to occur in the anterior uveal tract of felines, originating within the iris [1820], which was the possible origin in this case since it was affecting the anterior ocular chamber. In large felids, there are no data regarding ocular melanomas. Ocular melanomas can be locally infiltrative and may metastasize widely in cats [19, 21]. Data concerning metastatic potential and rate of metastasis in feline ocular melanomas are controversial. Although, some authors described that ocular melanomas in cats posses a high metastatic behavior [22, 23] attention should be paid to the fact that there are few long term survival studies regarding rate of metastasis in this type of cancer. In an observational study in domestic cats with diffuse iris melanomas, authors were not able to confirm with a satisfactory degree of reliability if the causes of death were truly associated with metastatic disease [24]. In this case, metastases to the liver and lungs were observed as has been described in cats. Neoplastic cells of the ocular neoplasm expressed Melan A and vimentin, similarly to those observed in domestic felines’ melanomas [25].

                    Mammary carcinomas were described in wild felids [26, 27] and were more common in animals that had been implanted with melengestrol acetate (MGA)-impregnated silastic devices [26]. Mammary mucinous carcinomas are tumor of the mammary gland characterized by presence of abundant mucin. This histologic pattern was described in a Tiger [28] and is rarely reported in the veterinary literature [2931]. Their prominent feature is the presence of large amounts of mucinous material with tintorial affinities to periodic acid-schiff (PAS), with and without diastase, and alcian blue stains [3236]. It was asserted that the predominant feature of this neoplasm is the presence of large amounts of mucinous material that stains positive to PAS, with and without diastase, and alcian blue stains [36]. In this case, positive staining of the mucus with PAS-diastase and an epitelial cytokeratin staining pattern indicated the presence of a mammary mucinous carcinoma.

                    Mucin-producing cells expressed cytokeratin, cytokeratin 19 and vimentin. This is similar to those observed in humans [37] and domestic felines, where luminal vimentin-positive epitelial cells were described [30].

                    This event is a consequence of neoplastic progression participating in the metastatic cascade and indicating a poor prognosis [3840]. Additionally, vimentin expression in human breast carcinomas is considered a malignancy indicator [37]. It is well known that feline mammary tumor express vimentin and that most of them are malignant [30]. Consequently, similar features apply to other felids’ mammary neoplasms.

                    Peribiliary cysts were observed in the liver. The cysts were primarily located in portal areas, with abundant fibrous tissue, and a single layer of epithelial cells. Differentiating biliary cysts from biliary cystadenoma can be challenging since the two entities are rather similar grossly and histologically [11]. Biliary cystadenoma is located within the parenchyma, whereas peribiliary cysts are located in the connective tissue of the hepatic hilus and also within the large intrahepatic portal tracts. Also, the typical biliary cystadenoma of domestic animals has a smaller amount of stromal content, in contrast to this case that exhibited abundant stromal component around the cysts. In humans, peribiliary cysts can have a genetic predisposition, or are associated with hepatobiliary disease, and exposure to chemical carcinogens [41, 42]. Peribiliary cysts have already been reported in African lions [11, 12] and there are no data regarding their aetiology in animals. Perhaps they are predisposed by the melanoma metastases in the liver in this case. Metastatic nodules could obliterate the necks of the peribiliary glands, resulting in the formation of retention cysts, as described by others [41].

                    The most plausible explanations for two different tumor in the same or separate organs are clonal variants of the same neoplasm, metastatic populations from separate tissue types of a mixed tumor, or metastases of two completely separate tumor. In this lioness, the tumor in her liver and lungs were grossly similar and required histological and immunohistochemical examination for better characterization. Immunohistochemistry is a useful tool to confirm the cell origin and differentiate multiple neoplasms and metastasis. In the present case, Melan A indirect immunohistochemistry was able to correctly differentiate between metastatic melanoma and mammary cell populations.

                    Conclusions

                    This is the first case in an African lion where there were two simultaneous neoplasms had metastasized. Additionally, this is the first case in which peribiliary cysts were associated with obliteration of hepatic tissue due to a metastatic neoplasm. Immunohistochemistry is a good ancillary tool for differentiation of cell populations in metastatic foci.

                    Declarations

                    Acknowledgments

                    The National Counsel of Technological and Scientific Development (CNPq) provided financial support for Noeme Rocha through the research grant 479178/2010-0. The São Paulo Research Foundation (FAPESP) provided financial support for Noeme Rocha through the research grants 2009/53493-9, 2010/51596-2, and 2011/01610-1.

                    Authors’ Affiliations

                    (1)
                    Departamento de Clínica Veterinária, Faculdade de Medicina Veterinária e Zootecnia, University Estadual Paulista – UNESP
                    (2)
                    Departamento de Patologia, Faculdade de Medicina de Botucatu, University Estadual Paulista – UNESP
                    (3)
                    Curso de Medicina Veterinária, Fundação de Ensino e Pesquisa de Itajubá – FEPI
                    (4)
                    Department of Diagnostic Pathology, Public Veterinary Hospital, Veterinary Service of National Association of Small Animal Clinicians (Anclivepa)
                    (5)
                    Departamento de Anatomia Patológica, Hospital A.C. Camargo. Fundação Antônio Prudente
                    (6)
                    Department of Pathobiological Sciences, Louisiana State University, School of Veterinary Medicine

                    References

                    1. White GL: A basal cell epithelioma in as African lion. Vet Med Small Anim Clin 1975, 70:1096.PubMed
                    2. Stolte M, Welle M: Cutaneous mast cell tumours in a lion ( Panthera leo ): a light and transmission electron microscopical study. J Comp Pathol 1995, 113:291–294.PubMedView Article
                    3. Odendaal JS, Van der Merwe SJ, Coetzee FP, Botha WS: Subcutaneous fibrosarcomas in a lion ( Panthera leo ). J S Afr Vet Assoc 1985, 56:143–144.PubMed
                    4. Tucker A, Ramsay EC, Donnell R: Oligodendroglioma in an African lion ( Panthera leo ). J Zoo Wildl Med 2008, 39:650–654.PubMedView Article
                    5. Dorso L, Risi E, Triau S, Labrut S, Nguyen F, Guigand L, Wyers M, Abadie J: High-grade mucoepidermoid carcinoma of the mandibular salivary gland in a lion ( Panthera leo ). Vet Pathol 2008, 45:104–108.PubMedView Article
                    6. El-Sergany M: Gastric carcinoma in a lion. Berl Munch Tierarztl Wochenschr 1966, 79:410–412.PubMed
                    7. Gilette DM, Acland HM, Klein L: Ductular mammary carcinoma in a lioness. J Am Vet Med Assoc 1991, 173:1099–1102.
                    8. Harrison TM, Mckinght CA, Sikarskie JG, Kitchell BE, Garner MM, Raymond JT, Fitzgerald SD, Valli VE, Agnew D, Kiupel M: Malignant lymphoma in African lions ( Panthera leo ). Vet Pathol 2010, 47:952–957.PubMedView Article
                    9. Sonmez G, Aytug N, Akkoc A, Cihan H, Alasonyalilar A: Intestinal adenocarcinoma with diffuse peritoneal carcinomatosis in a lion ( Panthera leo ). Eur J Wildl Res 2008, 54:385–389.View Article
                    10. Sakai H, Yanai T, Yonemaru K, Hirata A, Masegi T: Gallbladder adenocarcinomas in two captive African lions ( Panthera leo ). J Zoo Wildl Med 2003, 34:302–306.PubMed
                    11. Yu CH, Kim KT, Hwang DN, Yhee JY, Moon CT, Hur TY, Sur JH: Peribiliary cysts associated with severe liver disease: a previously unrecognized tumour in a lion ( Panthera leo ). J Vet Diagn Invest 2007, 19:709–712.PubMedView Article
                    12. Gerhauser I, Philipp U, Distl O, Beineke A: Multiple cyst formation in the liver and kidneys of a lion ( Panther leo ): a case of polycystic kidney disease? Eur J Wildl Res 2009, 55:433–437.View Article
                    13. Port CD, Maschgan ER, Pond J, Scarpelli DG: Multiple neoplasia in a jaguar ( Panthera onca ). J Comp Pathol 1981, 91:115–122.PubMedView Article
                    14. Doster AR, Armstrong DL, Bargar TW: Seminoma and parathyroid adenoma in a snow Leopard ( Panthera unica ). J Comp Pathol 1989, 100:475–480.PubMedView Article
                    15. ISIS, International Species Information System: Physiological reference values – American Units. Apple Valley, Minnesota: CD-ROM; 2002.
                    16. Frazier KS, Hines ME II, Ruiz C, Herron AJ, Altman NH: Immunohistochemical differentiation of multiple metastatic neoplasia in a Jaguar ( Panthera onca ). J Zoo Wildl Dis 1994, 25:286–294.
                    17. Dubielzig RR: Tumours of the eye. In Tumours in domestic animals. 4th edition. Edited by: Meuten DJ. Ames: Iowa State Press; 2002:739–754.View Article
                    18. Acland GM, McLean IW, Aguirre GD, Trucksa R: Diffuse iris melanoma in cats. J Am Vet Med Assoc 1980, 176:52–56.PubMed
                    19. Patnaik AK, Mooney S: Feline melanoma: a comparative study of ocular, oral, and dermal neoplasms. Vet Pathol 1988, 25:105–112.PubMedView Article
                    20. Day MJ, Lucke VM: Melanocytic neoplasia in the cat. J Small Anim Pract 1995, 36:207–213.PubMedView Article
                    21. Bellhorn RW, Henkind P: Intra-ocular malignant melanoma in domestic cats. Trans Ophthalmol Soc UK 1970, 89:321–333.PubMed
                    22. Pigatto JAT, Hünning PS, Almeida ACVR, Pereira FQ, Freitas LVRP, Gomes C, Schiochet F, Rigon GM, Driemeier D: Diffuse iris melanoma in a cat. Acta Scientiae Veterinariae 2010,38(4):429–432.
                    23. Planellas M, Pastor J, Torres MD, Peña T, Leiva M: Unusual presentation of a metastatic uveal melanoma in a cat. Veterinary Ophthalmology 2010,13(6):391–394.PubMedView Article
                    24. Kalishman JB, Chappell R, Flood LA, Dubielzig RR: A matched observational study of survival in cats with enucleation due to diffuse iris melanoma. Veterinary Ophthalmology 1998,1(1):25–29.PubMedView Article
                    25. Ramos-Vara J, Miller MA, Johnson GC, Turnquist SE, Kreeger JM, Watson GL: Melan A and S100 protein immunohistochemistry in feline melanomas: 48 cases. Vet Pathol 2002, 39:127–132.PubMedView Article
                    26. Harrenstien LA, Munson L, Seal US, The American Zoo and Aquarium Association Mammary Cancer Study Group: Mammary cancer in captive wild felids and risk factors for its development: a retrospective study of the clinical behavior of 31 cases. J Zoo Wildl Med 1996,27(4):468–476.
                    27. Owston MA, Ramsay EC, Rotstein DS: Neoplasia in felids at the knoxville zoological gardens, 1979–2003. J Zoo Wildl Med 2008,39(4):608–613.PubMedView Article
                    28. McAloose D, Munson L, Naydan DK: Histologic features of mammary carcinomas in zoo felids treated with melengestrol acetate (MGA) contraceptives. Vet Pathol 2007, 44:320–326.PubMedView Article
                    29. Hampe JF, Misdorp W: Tumours and dysplasias of the mammary gland. ICTDA/World Health Organization 1974, 50:111–133.
                    30. Martin de las Mulas J, Espinosa de los Monteros A, Bautista MJ, Gomez-Villamandos JC, Morales C: Immunohistochemical distribution pattern of intermediate filament proteins and muscle actin in feline and human mammary carcinomas. J Comp Pathol 1994, 111:365–381.PubMedView Article
                    31. Sarli G, Brunetti B, Benazzi C: Mammary mucinous carcinoma in the cat. Vet Pathol 2006, 43:667–673.PubMedView Article
                    32. Cooper DJ: Mucin histochemistry of mucous carcinomas of breast and colon and non-neoplastic breast epithelium. J Clin Pathol 1974, 27:311–314.PubMedView Article
                    33. Walker RA: Mucoid carcinomas of the breast: a study using mucin histochemistry and peanut lectin. Histopathology 1982, 6:571–579.PubMedView Article
                    34. Coady AT, Shousha S, Dawson PM, Moss M, James KR, Bull TB: Mucinous carcinoma of the breast: further characterization of its three subtypes. Histopathology 1989, 15:617–626.PubMedView Article
                    35. Misdorp W, Else RW, Hellmen E, Lipscomb TP: Histological classification of mammary tumours of the dog and cat. 2nd series. Washington: Armed Forces Institute of Pathology; 1999.
                    36. Misdorp W: Tumours of the mammary gland. In Tumours in domestic animals. 4th edition. Edited by: Meuten DJ. Ames: Iowa State Press; 2002:575–606.View Article
                    37. Niveditha SR, Bajaj P: Vimentin expression in breast carcinomas. Indian J Pathol Microbiol 2003, 46:579–584.PubMed
                    38. Gould VE: Histogenesis and differentiation: a reevaluation of these concepts as criteria for the classification of tumours. Hum Pathol 1986, 14:212–214.View Article
                    39. Thiery JP: Epithelial-mesenchymal transitions in development and pathologies. Curr Opin Cell Biol 2002, 15:740–746.View Article
                    40. Kalluri R, Weinberg RA: The basics of epithelialmesenchymal transition. J Clin Invest 2009, 119:1420–1428.PubMedView Article
                    41. Wanless IR, Zahradnik J, Heathcote EJ: Hepatic cysts of periductal gland origin presenting as obstructive jaundice. Gastroenteroly 1987, 93:894–898.
                    42. Seguchi T, Akiyama Y, Itoh H, Tanaka H, Naganuma S, Nagaike K, Uchiyama S, Kataoka H: Multiple hepatic peribiliary cysts with cirrhosis. J Gastroenterol 2004, 39:384–390.PubMedView Article

                    Copyright

                    © Cagnini et al.; licensee BioMed Central Ltd. 2012

                    This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://​creativecommons.​org/​licenses/​by/​2.​0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                    Advertisement