Hereditary breast cancer associated with Cowden syndrome-related PTEN mutation with Lhermitte-Duclos disease

BACKGROUND Cowden syndrome is characterized by multiple hamartomas in various tissues, including the skin, brain, breast, thyroid, mucous membrane, and gastrointestinal tract, and is reported to increase the risk of malignant disease. CASE PRESENTATION We describe the case of a 52-year-old woman in whom a tumor was diagnosed in the left cerebellar hemisphere and treated by surgical resection. Phosphatase and tensin homolog (PTEN) mutation in exon 8 insertion was found in the brain tumor tissue and leukocytes. This finding supported the diagnosis of Cowden syndrome. She consequently developed endometrial cancer and underwent abdominal total hysterectomy with bilateral salpingo-oophorectomy. Four years later, hormone receptor-positive breast cancer was found in the right breast, and breast-conserving surgery with radiation therapy and sentinel lymph node biopsy was performed. CONCLUSIONS Herein, we describe a patient who was diagnosed as having familial breast cancer associated with PTEN mutation-related Cowden syndrome. We also reviewed reports of this syndrome in the literature for disease appraisal.