Cutaneous mastocytomas in the neotenic caudate amphibians Ambystoma mexicanum (axolotl) and Ambystoma tigrinum (tiger salamander)

• Published in: Journal of cancer research and clinical oncology 1999-04, Vol.125 (3-4), p.187-192
• Main Authors: HARSHBARGER, J. C, SING CHEN CHANG, DELANNEY, L. E, ROSE, F. L, GREEN, D. E
• Format: Article
• Language: English
• Subjects: Ambystoma; Ambystoma mexicanum; Ambystoma tigrinum; Animal tumors. Experimental tumors; Animals; Biological and medical sciences; Hypodermis; Mast-Cell Sarcoma - pathology; Mast-Cell Sarcoma - ultrastructure; Medical sciences; Skin Neoplasms - pathology; Skin Neoplasms - ultrastructure; Spontaneous animal tumors; Tumors
• ISSN: 0171-5216; 1432-1335
• DOI: 10.1007/s004320050262

Spontaneous mastocytomas studied in 18 axolotls (Ambystoma mexicanum) and six tiger salamanders (Ambystoma tigrinum) were gray-white, uni- to multilobular cutaneous protrusions from 2 mm to 2 cm in diameter. Tumors were moderately cellular unencapsulated masses that usually infiltrated the dermis and hypodermis with the destruction of intervening tissues. Some tumors were invading superficial bundles of the underlying skeletal muscle. Tumors consisted of mitotically active cells derived from a single lineage but showing a range of differentiation. Immature cells had nearly smooth to lightly cleft or folded basophilic nuclei bordered by a band of cytoplasm with few cytoplasmic processes and containing a few small uniform eccentric granules. Mature cells had basophilic nuclei with deep clefts or folds and abundant eosinophilic cytoplasm with multiple long intertwining cytoplasmic extensions packed with metachromatic granules. The axolotls were old individuals from an inbred laboratory colony. The tiger salamanders were wild animals from a single polluted pond. They could have been old and inbred. Both groups were neotenic. These are the first mastocytomas discovered in cold-blooded animals.