What is the most likely cause of non-pitting edema?

Non-pitting edema is most commonly associated with lymphedema due to the accumulation of lymphatic fluid in the tissues. This condition occurs when there is a blockage or damage to the lymphatic system, preventing the proper drainage of lymph fluid. As a result, the affected area may feel firm and swollen, but when pressure is applied, the indentation (or pit) does not remain. This characteristic is what differentiates non-pitting edema from other types of edema, where pressing the skin may cause a temporary dent.

Lymphedema can occur due to various factors such as surgery, radiation of lymphatic tissues, or infections negatively impacting lymphatic drainage. In the context of this question, lymphedema stands out as the most likely cause of non-pitting edema among the options provided. Other conditions listed, like heart failure and venous insufficiency, typically result in pitting edema where the affected area retains a pit upon pressure due to the transient nature of fluid accumulation, which is different from the permanent or chronic nature seen in lymphedema.