Case report: Mesonephric-like carcinoma of the endometrium in a 73-year-old female

Mesonephric-like carcinoma (MLC) is a newly described malignant tumor that represents 1 % of endometrial cancers. The etiology of this disease is currently unknown but immunohistochemical expression with GATA-3, PAX-8 and TTF-1 and lack of ER/PR positivity can aid in correct diagnosis.

A 73-year-old female presented to our hospital with post-menopausal bleeding, an initial hysteroscopy identified a lesion suggestive of endometrial cancer. Ultimately, the patient underwent a hysterectomy and a bilateral salpingectomy/oophorectomy. Chemotherapy ensued due to metastatic disease. At 7 months post-op, the patient appeared to be doing well. Grossly, the lesion was 5.5 cm and appeared to infiltrate the entire thickness of the myometrium. Microscopically, densely packed malignant glands were seen with eosinophilic secretions. GATA-3, PAX-8 and TTF-1 immunostains were all positive. ER and PR immunostains were negative. Finally, a wild-type staining pattern was seen with p-53. PIK3CA and KRAS mutations have been observed in other cases of MLC.

Currently no standardized treatment regimen exists for this cancer; chemotherapy utilization including carboplatin and paclitaxel treatments are seen in medical literature. Researchers have explored the expression of the L1CAM adhesion molecule and have found higher expression in MLC compared to endometrioid endometrial carcinoma (EEC).

Awareness of this entity is important due to its rarity, clinical course, and histological similarities to EEC. Ultimately, eosinophilic secretions on histology and the specific immunophenotype can help guide a diagnosis of MLC.