Small sarcomas in the armpits can be caused by dermatomas, warts or lipomas, which are difficult to remove on their own. 1. Dermatomas: Dermatomas are also known as soft fibrous tumors of the skin. It is a proliferative benign tumor of the skin. It is usually found in obese people and pregnant women. Patients can be treated with surgery, laser or freezing under the guidance of a doctor. 2. common warts: common warts are caused by patients infected with human papillomavirus, which is somewhat contagious. It can be treated with topical retinoic acid cream, laser or electrocautery. 3. Lipoma: Lipoma is a kind of benign tumor, which can appear in any place where fat exists. At present, it is usually treated by surgical excision. For patients with small sarcoma under the armpit, it is recommended to go to regular hospitals for timely examination and standardized treatment under the guidance of professional doctors.