What is the most common cause of lymphedema in the United States?

• A. Filariasis
• B. Breast cancer surgery
• C. Hereditary
• D. Sarcoma

Answer: (B)

In the United States, lymphedema is most often a secondary condition caused by disruption of lymphatic drainage after cancer treatment, especially breast cancer surgery that removes or injures axillary lymph nodes and is often followed by radiation. When these lymph nodes are removed or damaged, the arm’s lymphatic pathways can’t drain properly, leading to persistent swelling.

Filariasis is a common global cause, but it’s not endemic in the US. Hereditary (primary) lymphedema occurs, but it’s much less common than post-treatment lymphedema. Sarcoma can cause swelling if it blocks lymphatics, but it is not the typical or most frequent cause.