イヌの膀胱腫瘍における自然史の病理組織学的検討 ： Ⅱ. N-butyl-N-(4-hydroxybutyl)nitrosamineにて発生したイヌの膀胱腫瘍の病理組織学的所見のMappingによる検討

Abstract

Histopathological mapping study was performed on the development and progression of urinary bladder tumor induced by N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in five adult beagle dogs and four adult mongrel dogs. The results are as follows : 1) Urinary bladder tumors induced by low doses of BBN showed papillary, non-invasive type, G1-2, pTa-1 carcinomas which were similar to human superficial bladder cancer ; 2) Microinvasion was occasionally observed in the papillary, non-invasive tumors induced by low doses of BBN, especially in the proliferated cells with atypia in the lamina propria ; 3) Urinary bladder tumors induced by high doses of BBN showed non-papillary, invasive type, G2-3, pT3b, and carcinoma in situ (CIS), which were similar to human invasive bladder cancer ; 4) No malignant progression was seen in low-grade, low-stage tumors during observation through the whole life of the dogs ; 5) The duration and the total dosage of BBN until bladder tumor occurred in beagle dogs were longer and higher than those of BBN in mongrel dogs ; 6) Those changes such as mild dysplasia and Brunn's nests-like lesion in lamina propria were seen during the development of low grade, papillary and non-invasive bladder tumors induced by low dose of BBN. On the other hand, those changes such as severe dysplasia and carcinoma in situ were seen during the development of non-papillary, invasive transitional cell carcinomas induced by high dose of BBN. The present study suggests that it contributed to knowledge of the natural history of bladder carcinogenesis in dogs, and is a valuable model of bladder carcinoma in humans.