A lump on the upper medial side of the right arm suggests consultation with general surgery, dermatology, or orthopedics, depending on the condition. Common causes of lumps on the inner side of the right arm may be sebaceous cysts, lipomas, epidermoid cysts, etc., as well as other causes such as bone cysts and bone tumors. 1. General Surgery: If the infection is caused by virus, bacteria and other pathogenic microorganisms, the localized mass accompanied by pain, fever and other symptoms may be lymphadenitis, and it is recommended to go to the General Surgery Department for consultation. 2. Dermatology: if the localized mass is obvious but not accompanied by pain, elastic, and can move slightly when pushed, it may be lipoma; if there is a clear boundary, medium hardness, and it is difficult to push the cysts, it may be sebaceous cysts, which are mostly formed due to the blockage of local follicles and sebaceous gland orifices. Dermatology can be consulted to clarify the size, nature, mobility, pressure and pain of the mass, and further examination of local ultrasound to clarify the nature of the mass, whether it is cystic, solid or cystic-solid mass. 3. Orthopedics: if there is a mass on the inner side of the right arm, which may be accompanied by vague pain or no obvious symptoms, it may be a simple bone cyst; if it is accompanied by pain on the inner side of the right arm or shoulder pain, it may be considered as a tumor, and it is recommended to consult orthopedics for a clear diagnosis. If there is a lump on the inner side of the right arm, you should go to the hospital in time and take active treatment, so as to avoid delaying the condition.