Fascial Hernias or Trigger Points: These are common causes of palpable knots in the lower extremities, often resulting from muscle strain, overuse, or direct trauma. They can cause localized pain and stiffness.

Varicose Veins: While not typically described as "knots," varicose veins can feel like cord-like structures under the skin and may be associated with pain and swelling.
Lipomas: Benign fatty tumors that can feel like knots under the skin. They are usually mobile and painless but can cause discomfort if they press on nearby nerves.
Cystic Lesions (e.g., Ganglion Cysts): These can present as firm, palpable masses under the skin, often around joints or tendons, and may cause pain or discomfort.

Deep Vein Thrombosis (DVT): Although DVT typically presents with swelling, warmth, and discoloration of the affected limb, it can sometimes cause palpable cord-like structures due to the thrombosed vein. Missing this diagnosis can be fatal due to the risk of pulmonary embolism.
Soft Tissue Sarcomas: Rare malignant tumors that can present as a palpable mass. Early detection is crucial for treatment and prognosis.

Neurofibromas: Benign nerve sheath tumors that can present as palpable knots along nerves. They are associated with neurofibromatosis type 1 (NF1) but can also occur sporadically.
Elastofibroma: A rare, benign soft tissue tumor that can occur in the lower extremities, among other locations, and may feel like a firm knot.
Hematoma or Pseudotumor: A collection of blood that can form a palpable mass after trauma. In some cases, it can become chronic and form a pseudotumor.