Malignant Melanoma of the Eyelid in a Red Squirrel(Sciurus vulgaris orientis).

Abstract

ABSTRACT. A 6-year-old male red squirrel (Sciurus vulgaris orientis) developed bilateral tumors of upper and lower eyelids. The tumors in the left lid recurred despite surgical removal. Necropsy revealed metastasis to the lung. The neoplastic cells were epithelioid and highly pleomorphic, and only a few cells contained melanin granules. Occasionally melanoma cells were immunoreactive for S100, neuron-specific enolase and vimentin, and a small number of cells for cytokeratin. Ultrastructurally, the presence of premelanosomes was confirmed in the cytoplasm. Possible presence of cytokeratin-positive neoplastic melanocytes should be taken into account when differentiating a nonpigmented epithelioid melanoma from other tumors such as anaplastic carcinomas.KEY WORDS: cytokeratin, malignant melanoma, squirrel.J. Vet. Med. Sci. 64(3): 261-264, 2002 Malignant melanoma of the eyelid has been reported in dogs [8], cats [16] and man [11]. Dutta et al. [2] reported an amelanotic malignant melanoma on the cervical skin of a ground squirrel. Although considered to be absent in canine and feline melanomas [10,16], cytokeratin has been observed in human malignant melanomas [4]. Our report describes a case of malignant melanoma of the eyelid skin in a red squirrel, in which cytokeratin immunoreactivity was detected.A 6-year-old, male red squirrel (Sciurus vulgaris orientis) had a 1-year history of right palpebral tumor masses and a 4-month history of left ones. Both upper and lower lids were involved, and the tumor of the upper left lid was excised for histological examination. The other three tumors were removed 12 days later. Because of corneal ulceration, the right eye was enucleated 8 days later. Recurrent tumors on the upper and lower lids of the left eye were excised 22 days after eye extirpation, but a recurrence was detected on the left lower lid and surgery was performed 14 days later. The left eye was removed owing to corneal ulceration 19 days after surgery, and the animal died the next day. The excised tumors were white and homogeneous, and ranged from 1.5 to 1.0 cm in diameter. At necropsy, a 5 mm diameter white lesion was detected in the lung.Surgically resected eyelid tumors and necropsied tissues were fixed in 10% buffered formalin and processed according to routine histological techniques. Paraffin sections were stained with hematoxylin and eosin (HE) and MassonFontana stains. Selected paraffin sections were stained by immunoperoxidase techniques using polyclonal antibodies to S100 protein (Nichirei, Tokyo, Japan), neuron-specific enolase (NSE) (Lipshaw, Detroit, U.S.A.) and cytokeratin (BioGenex Laboratories, San Ramon, U.S.A.) and a monoclonal antibody to vimentin (Dako, Carpinteria, U.S.A.). A universal kit was used in the subsequent processes. Small pieces taken from formalin-fixed tissues were post-fixed in osmium tetroxide and embedded in epoxy resin. Thin sections were mounted on copper grids, stained with uranyl acetate and lead citrate, and examined with a transmission electron microscope.The tumors e...

Histopathologic features of melanocytic tumors in <i>Xiphophorus</i> melanoma receptor kinase (<i>xmrk</i>)-transgenic medaka (<i>Oryzias latipes</i>)

“…Spontaneous malignant melanomas occur in several mammalian and bird species, but their incidence and the most frequently affected sites vary between species as well as among breeds within the same species 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 . For instance, malignant melanoma is relatively common in dogs and horses, but it is rare in cats, pigs, and cattle 2 .…”

“…Based on these histopathologic findings, the tumors were diagnosed as malignant melanoma. Mitotic figures in neoplastic cells are frequently observed in spontaneous malignant melanomas in several species of mammals and birds 1 , 3 , 5 , 7 , 8 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 . According to the World Health Organization Histologic Classification of Epithelial and Melanocytic Skin Tumors of Domestic Animals 19 , ≥3 mitotic figures per 10 high-power fields is indicative of malignancy.…”

Embryonal rhabdomyosarcoma in a Siberian chipmunk (Tamias sibiricus): a case report

“…There have been a few reports of naturally occurring tumours in squirrels, including mammary tumour (Shivaprasad et al 1984;Oohashi et al 2009), osteosarcoma (Tamaizumi et al 2007), lymphoma (Honnold et al 2007;Panakova et al 2010), melanoma (Fukui et al 2002), mast cell tumour (He et al 2009), squamous cell carcinoma (Trigo and Riser 1981), transitional cell carcinoma (Childs-Sanford et al 2015) and adenocarcinoma (Carminato et al 2012). However, to the best of our knowledge, RMSs…”

“…The Siberian chipmunk (Tamias sibiricus) is a member of the family Sciuridae within the order Rodentia that primarily inhabits Northeastern Asia and has been raised as a pet. There are a few reports of neoplastic diseases in squirrels (Trigo and Riser 1981;Shivaprasad et al 1984;Fukui et al 2002;Honnold et al 2007;Tamaizumi et al 2007;He et al 2009;Oohashi et al 2009;Panakova et al 2010;Carminato et al 2012;Childs-Sanford et al 2015); however, RMSs have not been reported. Here we provide the first report of a RMS in a Siberian chipmunk together with histopathological findings.…”

Influência do hipotireoidismo na progressão do melanoma experimental

“…Entre os animais selvagens, há relato de melanoma em pálpebras do esquilo vermelho e na conjuntiva de veado (FUKUI et al, 2002;SAKAI et al, 2001;GOLSCHMIDT;MCMANUS, 2002 Em outro estudo, observou-se que quatro dentre vinte pacientes com câncer renal e melanoma e que foram tratados com imunoterapia utilizando-se Interleucina-2 (IL-2) e Interferon alfa-2 (IFN-2 ), apresentaram evidência laboratorial de hipotireoidismo iatrogênico em decorrência a este protocolo de tratamento e, aparentemente, três destes pacientes obtiveram benefícios com esta condição, que resultou em 50% de regressão tumoral (SCALZO et al, 1990).…”