Most of the malignant tumors of the buttocks originate from mesenchymal tissues, and the differentiation mainly relies on imaging examination and pathological biopsy. 1. Imaging examination: the main means are color ultrasound, CT examination, magnetic resonance and so on, but this kind of examination can only be used as auxiliary examination to help diagnosis. 2. Pathological biopsy: the so-called biopsy is to take a part of the tissue from the lesion area by puncture or surgery, and do a pathological test, so as to finally distinguish the specific type clearly. Pathologic biopsy is the gold standard for diagnosis. Once the diagnosis of malignant tumor of the buttock is clear, it is necessary to consult the Department of Oncology or Department of Surgery of regular hospitals, and choose the appropriate treatment according to the pathological classification and staging.