CHAPTER 12 – Neoplastic Diseases

Publisher Summary This chapter provides an overview of the neoplastic process in the various rabbit species. It discusses the naturally occurring tumors of Oryctolagus, Sylvilagus, and Lepus, namely, neoplasms without known antecedent triggering mechanisms, and at least one important case, chronic inflammation subsequent to syphilitic orchitis. Squamous cell carcinoma of the vaginal squamous–columnar junction is a rare tumor. It is an important tumor, however, because in the rabbit the columnar epithelium of the uterus is continued out over the cervix into the vagina. The transition to squamous epithelium occurs at the level of the urethral meatus. Bile duct adenoma and its malignant counterpart, the bile duct adenocarcinoma, are relatively common as spontaneous tumors of Oryctolagus. Bile duct adenomas are present as a massive solitary growth or as multiple tumors of variable size. The lesions are unencapsulated and sharply circumscribed from the normal liver. The tumor is frequently described as a cystadenoma because the gross appearance of multiple interloculating cysts filled with honey-like fluid is matched by the microscopic pattern of variably differentiated ductalforms within a myxoid to fibrotic stroma. The Brown–Pearce carcinoma, one of the most useful of the transplantable rabbit tumors, arose from the syphilitic scrotal chancre of a rabbit.