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After a chance observation that multiple cutaneous papillomas and squamous cell carcinomas occurred in 2 adult mice heterozygous for the repeated epilation gene Er, we surveyed a panel of 10 +/+ (wild type) and 30 Er/+ (heterozygous) mice from birth to over 2 years of age. Homozygous Er/Er mice could not be included since their defect is lethal at birth. Whereas no cutaneous tumors developed in the +/+ mice, 20 of the Er/+ mice, males and females, had developed 1-5 cutaneous papillomas and at least 1 cutaneous invasive squamous cell carcinoma by 2 years of age. No lesions were seen in mice younger than 6 months old. Although almost all Er/+ mice died with their tumor burden, no metastases have yet been proven histologically. The Er/+ mouse should serve as a useful model for the exploration of genetic factors in cutaneous squamous cell carcinomas in humans.

Multiple melanophoromas in the axolotl Ambystoma mexicanum were characterized by cell anaplasia and polymorphism. Pigment spots may be the first stage of tumor development.

Pathologic studies were made on 18 Tasmanian devils that were necropsied at the San Diego Zoo. Spontaneous neoplasms and/or preneoplastic hyperplasia were the most frequently occurring diseases. Abnormal proliferative lesions were present in 9 animals; 6 of these had two or more concomitant proliferative diseases. Renal disease was observed in 7 animals.