Renal Tumors in the Rabbit

Abstract

New growths of any kind are evidently rare in rabbits. Although the rabbit is very extensively used for laboratory purposes, we have found reports of only thirty-five tumors. Twenty-four of the recorded tumors were uterine. Of these Stilling and Beitzke (1) have reported thirteen cases, noting a distinctly hereditary tendency to tumor formation. The youngest animal in their series was four years old. Boycott (2) has recorded four cases, and Wagner (3), Selinow (4), Katase (5), Marie and Aubertin (6), Leitch (7), and Shattock (8) have found one each. Shattock and Leitch both agreed that the case described by Lack (9) was really a primary uterine tumor with metastases. Schmorl (10) reported one case of carcinoma of the lung and a second case with carcinoma of the stomach. Von Dungern (11) and Baumgarten (12) each described a case of sarcoma, while Schultz (13) has done some very interesting work with a transplantable round cell sarcoma. Petit (14) has recorded a primary carcinoma of the lung and a carcinoma of an accessory pancreas in the omentum, and Bashford (15) has found a carcinoma of the mamma and a sarcoma of the subcutaneous tissue. Of the thirty-five tumors recorded, only two were tumors of the kidney. The first, described by Lubarsch (16) in 1905, was similar to the two that we are reporting. In Lubarsch9s case the growth occupied the upper half of the left kidney, and was sharply marked off from the renal tissue. Upon microscopic examination it was found to be composed mainly of gland-like structures of varying form and width, embedded in a very cellular stroma. Lubarsch noted that the histological structure bore a close resemblance to the human renal tumor commonly described as an adenosarcoma; no cartilage, squamous epithelium, or striated muscle were found, and no Malpighian corpuscles were mentioned. Pieces of the tumor were inserted into the kidneys of four rabbits, with negative results. The kidney had been previously inoculated with embryonic salivary gland tissue but the author did not believe that the tumor grew from this implant; he thought, however, that the injection might have stimulated tissue rests to growth. The second renal tumor was reported by Nurnberger (17) in 1912. The growth was situated in the upper half of the right kidney and produced a spherical smooth elevation of the surface about the size of a cherry; a sagittal section through the organ showed a tumor measuring 1.5 cm. by 1.3 cm., and displacing about one-third of the renal tissue. Microscopically, the tumor was composed of numerous cysts of varying size lined with cubical or flattened epithelium, and of large numbers of gland-like tubules lined by high columnar epithelium taking a basic stain and showing many mitotic figures. In some of the tubules the epithelium formed more than one layer; in others there was no lumen, the structure appearing as a solid cord. Between the tubules and cysts there was a cellular connective tissue. Smooth muscle fibers were noted under the capsule of the tumor; no striated muscle, cartilage, bone, or elastic tissue was present. Nurnberger recorded his case as a mixed tumor, and compared it to the embryonal glandular tumors found in man. Our two neoplasms occurred in adult male rabbits, both having been found on the same afternoon; and although we have autopsied over four hundred rabbits during the last three years, no other tumors have been seen. We were not able to ascertain the ages of the rabbits, neither could we determine whether they were both from the same litter, since animals obtained from different persons had been put into a cage together.