Cerebral cavernous malformations (CCMs) are angiographically occult cerebrovascular malformations (AOVM) of the central nervous system. They are composed of a sponge-like abnormal vascular mass with numerous thin-walled vessels. CCM incidence rate is approximately 7% of cerebrovascular malformations. The clinical manifestations mainly include seizures, bleeding, headache, etc., with seizures being the most common first symptom, and some patients may be without clinical manifestations. MRI has been the specific diagnostic method for CCMs. This article reports the case of a patient initially diagnosed with multiple myeloma in the left temporal lobe at our hospital in September 2020. Later, the patient was confirmed to have CCMs through surgery and pathology. The main symptom was a sudden onset of cognitive dysfunction, and the patient was discharged after receiving symptomatic and surgical interventions.