A lump on the right side of the back at the ribs may be a lipoma, boil, or bulging dermatofibrosarcoma. 1. Lipoma: it is a tumor of adipose tissue, preferably occurring in the trunk and limbs. Lumps have clear boundaries, soft texture, cystic and painless to touch, slow growth, but can reach a huge size, which can be manifested as a lump on the right side of the back at the ribcage. 2. Boil: It is due to bacterial infection of hair follicles and surrounding tissues, resulting in purulent inflammation. The bacteria, mostly found in Staphylococcus aureus, are commonly found on the back and neck, causing the patient to feel a lump on the right side of the back at the ribs. Patients are often accompanied by generalized discomfort, such as chills, fever, and loss of appetite. 3. Elevated dermatofibrosarcoma: commonly found in trunk, originated from the dermis layer of the skin, with smooth surface skin and keloid-like elevation on the surface, which can manifest as a lump at the right side of ribs in the back, with low malignancy and easy to recur after excision. There may be other causes, such as cavernous hemangioma, sebaceous cysts, etc., which should be consulted in time, and the doctor should be asked to clarify the specific causes, and the corresponding treatment should be carried out if necessary.