<s>[INST] I have a small hard pea sized lump on the back of my thigh, which is a slightly discoloured (purple), it s been there for about 6months and does not hurt at all. When should you worry about lumps on the skin? I thought it might be an ingrown hair but surely that would hurt? There is no sign of infection. [/INST] Hi.Thanks for your query and an elucidate history.Any lump at the back side of the thigh should be removed/ excised. This is a pressure-area.. and the lumps will cause a problem some or the other day.. So get this excised ::It is better to get this removed (excised) for 2 reasons.1> your get rid of the disease and 2> you get the histopathological diagnosis- makes you tension-free.. </s>