A vague foreign body sensation without pain under the left rib cage may be due to sebaceous cyst, old fracture, osteochondroma and so on. 1. Sebaceous cyst: It may be that the local sebaceous gland secretes exuberantly and its discharge is obstructed, which will result in localized expansive growth and produce a foreign body sensation. If it occurs in the left rib cage, it may manifest as a foreign body sensation in the left rib cage, without pain. Smaller cysts are usually asymptomatic. 2. Old fracture: When the fracture heals, localized hyperplasia may occur, resulting in a prominent growth. When touching the skin, there may be a sensation of a foreign body healing, but during the recovery period, the local inflammatory reaction has gradually disappeared, so there is usually no obvious pain. If it occurs in the left rib, there will be a foreign body sensation in the left rib but no pain will be felt. 3. Osteochondroma: it can be manifested as a hard mass, usually without pressure pain, so if osteochondroma occurs in the left rib, there may be a foreign body sensation in the left rib but no pain, except for pathologic fracture. The left side of the ribs vaguely have a foreign body sensation does not hurt, there may be other reasons, when this symptom occurs and continues to be unrelieved should be timely consultation, improve the relevant examination, comply with the doctor’s instructions for treatment, so as not to delay the condition.