A lump in the buttocks is a bit painful, may be boils, sebaceous cysts secondary infection, perianal abscess, hemorrhoids and other causes. 1. Boil: is due to the deep follicles and the surrounding tissues of purulent infection, the early stage will cause subcutaneous nodules and lumps, skin redness, swelling, heat, pain and other inflammatory manifestations, may cause a lump in the buttocks a little pain. 2. Sebaceous cysts secondary infection: sebaceous cysts can cause pain if there is secondary infection. It can also lead to the symptom of a lump in the buttocks and a little pain. 3. Perianal abscess: secondary infection of the soft tissues of the anus or the interstitial space, the formation of purulent abscesses, can also lead to a lump in the buttocks a little pain. 4. hemorrhoids: external hemorrhoids and mixed hemorrhoids may cause a protruding anal mass, pain, resulting in the buttocks have a lump a little pain symptoms. In addition, internal hemorrhoids prolapse embedded, may also appear lump and pain performance. The buttocks have a lump a little pain, there may be other reasons, need to go to the hospital in time for examination, clear cause of the treatment as prescribed by the doctor.