What is hydatidiform mole (complete and partial)?

➢ The typical hydatidiform mole is a voluminous mass of swollen, sometimes cystically dilated, chorionic villi, appearing grossly as grapelike structures. ➢ Varying amounts of normal to highly atypical chorionic epithelium cover the swollen villi. ➢ There are two distinctive subtypes of hydatidiform moles: complete and partial. ➢ Complete hydatidiform moles are not compatible with embryogenesis and rarely contain fetal parts. All of the chorionic villi are abnormal, and the chorionic epithelial cells are diploid (46,XX or, uncommonly, 46,XY). ➢ The partial hydatidiform mole is compatible with early embryo formation and therefore may contain fetal parts, has some normal chorionic villi, and is almost always triploid (e.g., 69,XXY) ➢ Both types result from abnormal fertilization with an excess of paternal genetic material. ➢ In a complete mole the entire genetic content is supplied by two spermatozoa (or a diploid sperm), yielding diploid cells containing only paternal chromosomes. ➢ Whereas in a partial mole a normal egg is fertilized by two spermatozoa (or a diploid sperm), resulting in a triploid karyotype with a preponderance of paternal genes.