Malignant mixed müllerian tumor of the ovary and false negative punctures

Malignant mixed müllerian tumour (MMMT) of the ovary is a rare and aggressive tumour with a poor prognosis. We present a case of a 57-year-old woman with a large pelvic mass, omental cake, ascites and pleural effusions, clinically highly suspect of an ovarian neoplasm. Paracentesis and ultrasound-guided biopsy of the ovary were negative for malignant disease. Therefore a CT-guided true cut biopsy was performed. The latter gave a histopathologic diagnosis of an endometrioid adenocarcinoma of the ovary. However after cytoreductive surgery anatomopathologic examination revealed a malignant mixed müllerian tumour of the ovary with heterologous differentiation. Apparently only one of the two components was found in the puncture. Adjuvant chemotherapy, active against the sarcomatous and the carcinomatous component, was given. At present the patient is well and disease free 35 months after the initial diagnosis. Cytological examination of ascites may be negative in the presence of malignant disease. If a tumour consists of two components, puncture can miss one, which may lead to undertreatment. Punctures should be discouraged as a diagnostic tool in patients in whom an ovarian malignancy is suspected.