What Causes A Large Lump On Ankle On Being Diagnosed With Mantle Cell Lymphoma?

A family member has Mantle Cell Lyphoma. Dx is 2010.. Hes been taking oral meds for this. After other treatmenst .My question is. He has a lump on his ankle twice the size of a half dollar and has some purple coloration. He sees his oncologist this month. Is this a sign of coming out of remission