This is a report of papillary endothelial hyperplasia in a 9-year-old girl with a pilomatricoma showing bullous appearance. Histologically, papillary proliferation of endothelial cells was found within dilated lymphatic endothelium-lined vascular channels overlying a pilomatricoma. The endothelial cells covering the papillae were of a lymphatic endothelial cell nature proved by immunohistochemi...

Tumor development was examined sequentially in the nasal cavity of male F344 rats given 0.01% 1,4-dinitrosopiperazine (DNP) in their drinking water for various periods. Rats were sacrificed at 10-week intervals for up to Week 50. On continuous DNP administration, simple hyperplasia of the nasal cavity epithelium was observed from Week 10, papillary hyperplasia, nodular hyperplasia, and papillom...