Cerebellar dysplastic ganglioneuroblastoma, also known as Lhermitte-Duclos disease, is a benign tumor located mainly in the cerebellar hemispheres and has a relatively good prognosis, but it should be noted that the disease is part of Cowden syndrome, which may be combined with multiple organ diseases, especially some malignant tumors, such as breast cancer and thyroid cancer. Current data show that 20-25% of Cowden syndrome patients have breast cancer; 3-10% have thyroid cancer; 40% have gastrointestinal polyps; and 5-10% have endometrial cancer. Other lesions include renal cell carcinoma, melanoma, arteriovenous malformations, thyroid adenoma, and spinal cavernous lesions. And Cowden syndrome belongs to a kind of PTEN gene mutation syndrome, patients will have PTEN gene mutation, we once collected 10 patients from the neurosurgery department of Tiantan Hospital and also confirmed this, especially female patients, patients have a higher probability of endometrial cancer and breast cancer. Preventive measures: We believe that patients with LDD and their immediate family members should be examined in detail to exclude Cowden syndrome, and patients with Cowden syndrome should also be examined by cranial MRI to exclude LDD. The NCCN guidelines recommend: monthly breast self-examinations after the age of 18 years (females); annual thyroid ultrasound after the age of 18 years; annual detailed whole-body examination after the age of 18 years; and annual mammography or breast MRI after the age of 30-35 years for female patients. Some scholars recommend prophylactic bilateral mastectomy for women with Cowden syndrome, but the clinical significance of this remains to be considered. The famous Hollywood actress Angelina Jolie has been diagnosed with BRCA. Jolie underwent prophylactic mastectomy with bilateral ovariohysterectomy for BRCA mutation, the clinical significance of which is somewhat similar to that of PTEN mutation. The clinical significance is somewhat similar to that of PTEN mutation. For patients with PTEN mutation, there is no definite decision on whether to use the above procedure.