Cutaneous Neoplasms in Pet Rabbits: A Retrospective Study

Abstract

Abstract. Over a 16-year period, 190 tumors and tumorlike lesions from 179 pet rabbits were submitted for histopathologic examination. A total of 23 different tumor types and 1 tumorlike lesion were diagnosed. The most common diagnoses were trichoblastoma, collagenous hamartoma, and Shope fibroma. Viral-induced tumors were Shope fibroma (19) and Shope papilloma (2). Common nonviral epithelial tumors included trichoblastoma (59), squamous cell carcinoma (5), squamous papilloma (4), trichoepithelioma (3), and apocrine carcinoma (3). Common mesenchymal tumors were lipoma (10), liposarcoma (3), myxosarcoma (9), malignant peripheral nerve sheath tumor (8), fibrosarcoma (7), and leiomyosarcoma (4). Malignant melanoma was diagnosed in 8 rabbits. Collagenous hamartomas were diagnosed in 26 rabbits. Mesenchymal proliferations occurred significantly more often in male rabbits than in females. Collagenous hamartomas and myxosarcomas occurred exclusively in male animals, and 3 rabbits had multiple collagenous hamartomas. Immunohistochemistry was applied in cases in which a definite diagnosis could not be reached on hematoxylin and eosin slides. Follow-up information was received in 19 cases. Carcinomas recurred (2 of 3) or metastasized (1 of 3), whereas sarcomas frequently recurred (7 of 12). One malignant melanoma (1 of 3) and one poorly differentiated round cell neoplasm recurred (1 of 1). This is the first comprehensive retrospective analysis on skin neoplasia in pet rabbits.

The Malassezia Genus in Skin and Systemic Diseases

“…Additional epidemiological data from different animal species on the rate of Malassezia colonization implied a role for this yeast in the induction of this type of cancer. Malassezia yeasts and basal cell carcinoma are more common in dogs and cats (33), while they are extremely rare in lagomorphs and rodents (325). In dogs and cats, these tumors develop on the head and neck region (272), overlapping with the Malassezia niche in these animals.…”

Dermatologic Diseases

“…22,33 Nonviral skin tumors include squamous cell carcinoma, basal cell tumor, trichoepithelioma, trichoblastoma, sebaceous cell carcinoma, nonviral squamous papilloma, apocrine carcinoma, meibomian adenoma, sebaceous carcinoma, lipoma, liposarcoma, myxosarcoma, nerve sheath tumor, fibrosarcoma, leiomyosarcoma, leiomyoma, rhabdomyosarcoma, anaplastic sarcoma, and malignant melanoma. 75 Uterine adenocarcinoma and connective tissue tumors can metastasize to skin. 75 Uterine adenocarcinoma and connective tissue tumors can metastasize to skin.…”

Amelanotic Melanoma in a New Zealand White Rabbit (Oryctolagus cuniculus)

“…All tumors contained abundant melanin. 2 Melanomas have been reported in other species, including cat, 18 opossum, 16 monkey, 20 rat, 15 dog, 14 ferret, 27 and horse. 17 Melanomas account for 7% of all malignant tumors in dogs and are most often found in the oral cavity, with metastases commonly occurring in the lung and lymph nodes.…”