Hydatidiform moles are associated with numeric alterations of immune cell infiltrate. The numeric dominance of immune cells in the hydatidiform moles may reflect either non-specific or specific immunological processes. The possible pathogenetic and prognostic ramifications of our findings are open for further investigations.

Based on the present case and on previous studies, primary peritoneal MMMT seems to be a rare but highly malignant neoplasm with an aggressive behavior and poor prognosis. Its exact origin, histogenesis and molecular alterations are poorly understood.