LAUSR

Cowden syndrome (CS) is a multiple hamartoma syndrome associated with the development of various tumors, including endometrial cancer. However, the histology of CS-associated endometrial cancer remains to be fully described. To our knowledge, this is the first report of a patient with CS having endometrial endometrioid carcinoma with ovarian metastasis demonstrating morula-like features. A 31-yr-old, nulliparous, Japanese woman presented with abnormal genital bleeding. Endometrial biopsy revealed endometrioid carcinoma with an extensive morular formation, partially resembling atypical polypoid adenomyoma (APAM). Moreover, she had a past history of bilateral breast cancer and a family history of juvenile breast cancer in her mother. Genetic testing revealed they shared the same pathogenic germline PTEN mutation. She underwent an abdominal hysterectomy, bilateral salpingo-oophorectomy, and pelvic lymph node biopsy. Pathologic examination revealed endometrial endometrioid carcinoma with APAM-like histology. Furthermore, the solid components with morula-like morphology and immunophenotypes showed myometrial invasion and ovarian metastasis (FIGO stage IIIA/pT3aN0M0). The present case highlights the need for careful assessment of myometrial invasion and extrauterine spread for appropriate gynecologic treatment even if endometrial biopsy shows APAM-like histology. Moreover, characterization of CS-associated endometrial cancers is required.