Peau d' orange is due to -
Peaud's orange is produced due to obstruction of superficial lymph vessels by cancer cells. This causes edema of the skin giving rise to an appearance like that of the skin of an orange (Peau'd orange appearance) Ref - Srb's manual of surgery 5e p534
Secondary infection
Blockage of subdermal lymphatics
Invasion of skin with malignant cells
Aerial obstruction
Endocrinology and breast