Cowden syndrome is extremely rare and is characterized by multiple
hamartomas in various tissues, including the skin, mucous membranes, gastrointestinal tract, breast, thyroid, and brain, and has an increased risk of breast, thyroid, and
uterine cancers. Here, we report a case of
Cowden syndrome diagnosed following presentation with bilateral
breast cancer and provide a discussion of the relevant literature. A 47-year-old woman with a
tumor in her right breast was referred to our hospital. She was diagnosed with bilateral
breast cancer upon imaging and underwent a bilateral
mastectomy and sentinel lymph node biopsy. Previously, she had undergone total
thyroidectomy to treat a thyroid
tumor. Approximately 3 years later, she was diagnosed with
Lhermitte-Duclos disease affecting her left cerebellar hemisphere. As her sister and mother had also been diagnosed with
breast cancer, we suspected that she might have an inherited disease. Since 80% of individuals with
Cowden syndrome have a mutation in the
phosphatase and tension homolog (PTEN) gene, we did not perform any genetic testing. Instead, we used the syndrome's pathognomonic criteria and major criteria (
breast cancer, thyroid
tumor, and
Lhermitte-Duclos disease) to diagnose our patient with
Cowden syndrome. While treatment of
Cowden syndrome is currently limited to strategies that can manage the symptoms, patients are at an increased risk of certain
cancers and require regular screening to allow for early detection of disease.