Primary Ocular Melanoma in Dogs

Abstract

Abstract. The clinical signs, gross and microscopic appearance, treatment, and follow-up results of 35 dogs with primary ocular melanomas are reviewed. The melanomas are classified as epibulbar or intraocular based on the site of origin. The intraocular tumors are classified as spindle A, spindle B, mixed spindle B and epithelioid, and purely epithelioid based on cytologic criteria. The pathologic findings are matched with the follow-up history in an attempt to determine which features have prognostic significance. The findings are contrasted to those of similar studies of spontaneous ocular melanomas in man.Canine ocular melanomas, although rare, are the most common primary ocular neoplasm in the dog [ l , 2, 6-10, 12, 14, 171. No studies correlating the clinical, gross and microscopic appearance with treatment results and biologic behavior of the tumors have been reported to date. These canine tumors have been classified using criteria similar to those used in ocular melanomas in man [ 161. The prognosis in the dog, as in man, has been related to cell type. The validity of this approach for the dog is unknown because of small numbers reported and lack of follow-up information. The purpose of this report is to begin a preliminary study to correlate morphologic findings with biological behavior. Materials and MethodsCase records of dogs with ocular melanomas seen between 1964 and I980 were reviewed. Practitioners who submitted biopsies were contacted for additional information, and when necessary, owners were called to obtain further data. Age, breed, sex, site of occurrence, morphologic appearance, and clinical behavior of the tumors were compiled.Material collected for histology was fixed in either 10% buffered formalin or Zenker's solution and processed routinely for light microscopy. Deeply pigmented sections were bleached with hydrogen peroxide prior to staining. Tissues for transmission electron microscopy were dissected from formalin-fixed tissues, washed in buffer, and postfixed in osmium tetroxide prior to embedding in an epoxy resin. One pm sections were used for tissue orientation and selection of areas to be viewed by electron microscopy. After trimming. blocks were sectioned with a diamond knife, stained with uranyl acetate and lead citrate, and examined with an electron microscope.

Estudo morfológico das neoplasias melanocíticas uveais em cães

“…As células fusiformes A descritas por Callander (1931) em seres humanos e por Diters et al (1983) e Ryan e Diters (1984) em cães, não estavam presentes na amostra do presente estudo. Wilcock e Peifer (1986) e Dubielzig et al (2010) descreveram essas tipo celular como sendo componentes de alguns melanocitomas caninos, onde há presença de células fusiformes com baixo grau de pleomorfismo e atipia nuclear, explicando assim a classificação equivocada dessas células por alguns autores.…”

“…Essas células foram consideradas como epitelióides no passado, mas lhes faltam as características de anaplasias nuclear e citoplasmática no qual caracteriza as células epitelióides dos melanomas oculares (DITERS et al, 1983). Essas células também já foram consideradas macrófagos, porém uma análise das estruturas citoplasmáticas pela microscopia eletrônica revelou pré-melanossomos ou melanossomos maduros não fagocitados, provando tratar-se de células neoplasicas.…”

“…Para Diters et al (1983), o critério usado para diferenciação entre fusiforme A, fusiforme B e epitelióide são características normalmente usadas para diferenciar melanoma benigno e maligno. Diters et al (1983) referem que há melanomas de células fusiformes A quando há predominância de células fusiformes pequenas com núcleo alongado e delgado, com proporção núcleo/citoplasma pequeno e figuras de mitose extremamente raras.…”

“…Diters et al (1983) referem que há melanomas de células fusiformes A quando há predominância de células fusiformes pequenas com núcleo alongado e delgado, com proporção núcleo/citoplasma pequeno e figuras de mitose extremamente raras.…”

“…As células epitelióides também apresentam anaplasia nuclear com nucléolo proeminente, mas o citoplasma é redondo ou poligonal em vez de alongado. Diters et al (1983), Ryan e Diters …”