What best describes the condition of a 46-year-old female with bilateral lower-extremity edema and a history of increased left lower leg size?

The condition described best aligns with multi-factorial lymphedema due to the combination of bilateral lower-extremity edema and a history of increased size specifically in the left lower leg. Multi-factorial lymphedema often arises from a combination of various factors, including chronic venous insufficiency, obesity, or a previous history of conditions leading to lymphatic dysfunction.

In this case, the presence of bilateral edema alongside a noted increase in size of one leg suggests that there may be multiple contributing factors to the lymphedema. The asymmetry in size, particularly in the left leg, indicates that a potential lymphatic compromise could be exacerbated by other existing conditions, which is characteristic of multi-factorial lymphedema.

Examining the other potential conditions: lipedema primarily presents with disproportionate fat distribution affecting primarily women, usually sparing the feet, and does not typically present with unilateral leg size increase; primary lymphedema is often congenital or develop during puberty or pregnancy and tends to have a genetic basis; chronic venous insufficiency would typically cause swelling that may not be unilateral or associated primarily with lymphatic issues, often leading to other differentiating symptoms such as skin changes or ulceration.