PMC7297480_01
Placental gross findings. (A) The umbilical cord is dusky and hypercoiled with approximately 6 coils per 10 cm length. (B) On cross section, the placental parenchyma is pale pink-tan with a discrete 2.8cm firm, white-tan, whorled-appearing nodule underlying the maternal surface and extending nearly to the fetal surface.
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The umbilical cord was dusky, edematous, and hypercoiled, with a coiling index of 0.6 (17 coils per 28 cm; expected coiling index 0.1-0.3), right-handed twist, and eccentric insertion 1 cm from the placental disk edge (Figure 1A). The placental parenchyma was pale pink-tan and contained a well-defined, firm, white-pink intraplacental nodule (2.8 cm) with a whorled-appearing cut surface, involving the maternal surface and approaching within 0.5 cm of the fetal surface, overall occupying approximately 20% of the maternal surface (Figure 1B).
Placental leiomyoma histological findings. (A) On low power, there is a well-defined solid nodule underlying maternal decidua and distinct from the fetal surface (4x). (B) There is decidua with implantation-site trophoblasts (top of image; arrows) overlying the leiomyoma (100x). (C) At the interface of the placental parenchyma with the leiomyoma, there are implantation-site trophoblasts infiltrating into the leiomyoma (arrows; 100x). (D) The leiomyoma consists of long fascicles of spindled cells with eosinophilic cytoplasm and long tapered nuclei (100x). Inset: Tumor cells are diffusely positive for smooth muscle actin (100x).
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Histologically, the nodule was well-circumscribed and consisted of long fascicles of spindled cells with long tapered nuclei and no significant atypia or mitotic activity; these cells were diffusely positive for smooth muscle actin, consistent with leiomyoma (Figure 2).
Other histological findings. (A) The basal plate distant from the leiomyoma shows large fragments of adherent myometrial fibers (arrows; 40x). (B) Placental villi show diffuse loss of vascularity and sclerosis, as well as accelerated villous maturation with small terminal villi and increased syncytial knots (40x). (C) Adjacent to the leiomyoma, there is a parenchymal infarct with loss of nuclear basophilia and villous agglutination (40x). (D) Decidua adherent to the surface of the leiomyoma shows retention of smooth muscle in spiral arterioles (arrows; 200x).
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Distant from the leiomyoma, there were foci of smooth muscle fibers consistent with myometrium adherent to the maternal surface of the placenta and adjacent to extravillous trophoblasts and rare sclerotic villi with few layers of intervening decidua (Figure 3A). Consistent with the maceration changes seen in the fetus, the placenta showed diffuse changes consistent with intrauterine fetal demise, including extensive villous fibrosis and fetal vessel thrombosis with recanalization (Figure 3B). Changes of maternal vascular malperfusion were also evident, including hypermaturity with multiple small villi and syncytial knots (Figure 3B) as well as a 0.7-cm placental infarct adjacent to the leiomyoma (Figure 3C). Within the decidua adherent to the surface of the leiomyoma, spiral arterioles showed retention of a smooth muscle layer (Figure 3D).