A broken nevus is not necessarily cancerous, and whether it will become cancerous is related to the specific condition of the patient. Moles are mostly seen in congenital nevus, junctional nevus, intradermal nevus, mixed nevus and other diseases. When the skin in the area of nevus is broken, this has no direct carcinogenic effect. However, if the skin at the broken area is not healed, and is continuously stimulated by inflammation and other abnormalities for a long time, or is repeatedly broken, it may lead to abnormal differentiation of local cells, resulting in cancerous changes. Therefore, a broken nevus is not necessarily cancerous, but attention should be paid to promote the healing of the skin lesion in time. Whether nevus is cancerous or not is generally related to the patient’s condition, such as nevus is congenital pigmented nevus with large area, which is caused by gene mutation, and this kind of nevus has a high chance of malignant transformation; if the nevus has abnormal hyperplasia, enlarged area, irregular edges, itching and pain, it suggests that malignant transformation is at high risk, and the patient should consult a doctor for examination in time. In daily life, patients with nevus should pay attention to avoiding stimulation of the local area and reducing sun exposure, and when abnormal symptoms appear, they should receive professional treatment as soon as possible to avoid delaying the condition and leading to adverse consequences.