Diffuse dermal angiomatosis (DDA) is a rare, benign, acquired vascular disorder, classified as a distinct form of cutaneous reactive angiomatosis (benign, rare vascular processes characterized by intravascular proliferation and hyperplasia of endothelial dermal cells).

DDA predominantly affects middle-aged women. However, it can occur in both men and women. The disease has been documented across diverse racial / ethnic backgrounds, including in White, Black, and Asian populations.

DDA is typically localized and is most commonly reported to affect the breasts, especially occurring in women with macromastia. It is also associated with medical conditions that increase susceptibility to ischemia, including severe peripheral vascular disease, hypertension, or diabetes (type 1, type 2), arteriovenous fistulae, obesity, and with smoking. Ischemia with or without superadded inflammation leads to localized hypoxia. This hypoxic environment triggers an upregulation of vascular endothelial growth factor (VEGF), resulting in the proliferation of endothelial cells (neovascularization).