title: Malignant melanoma of the eyelid in a red squirrel (Sciurus vulgaris orientis).
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.
authors: Asahikawa Zoological Park and Wildlife Conservation Center, Higashi-Asahikawa, Japan.
authors: Daisuke
authors: D
authors: Fukui
authors: Gen
authors: G
authors: Bando
authors: Masao
authors: M
authors: Kosuge
authors: Masanori
authors: M
authors: Yamaguchi
authors: Tomoyuki
authors: T
authors: Shibahara
authors: Koichi
authors: K
authors: Kadota
mesh_terms: D000818:Animals; D005142:Eyelid Neoplasms / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D017809:Fatal Outcome; D007150:Immunohistochemistry / Q000662:veterinary; D008175:Lung Neoplasms / Q000473:pathology / Q000556:secondary / Q000662:veterinary*; D008297:Male; D008545:Melanoma / Q000473:pathology / Q000556:secondary / Q000601:surgery / Q000662:veterinary*; D012376:Rodent Diseases / Q000473:pathology* / Q000601:surgery; D012589:Sciuridae