There are many reasons for a little yellow dots muscle in the middle of the upper chest, such as flat warts, skin sarcoma, fat particles and so on. 1. flat warts: due to long-term sun exposure, low immune function or usually do not pay attention to the health of the human body infected with human papillomavirus flat warts, commonly in the face, back of the hand, chest and other parts of the surface smooth, hard texture, usually no self-conscious symptoms. 2. Skin sarcoma: originating from fibroblasts within the skin, belonging to malignant tumors, initially manifested as a single confined skin bulge, the early stage can be active, mostly seen in middle-aged men. 3. Fat grain: endocrine disorders, consuming too greasy food or not paying attention to chest skin cleaning, pore clogging, resulting in chest skin pore clogging, sebum is covered by keratin, resulting in fat grain. There is a little bit of yellow dots muscle in the middle of the upper chest may have other causes such as eczema, etc. If there are uncomfortable symptoms, you should go to the hospital in a timely manner to identify the causes and standardize the treatment.