Placental site trophoblastic tumor: a case report and review of the literature

Abstract

We present a case of a gravida 1 para 1 woman, who presented with an 11-month history of amenorrhea after cesarean delivery. The patient was taking birth control pills at the time of presentation. She was observed with a slight elevation of serum β-hCG level, an enlarged heterogeneous uterus and hematometra. A biopsy was performed, and the patient was diagnosed with placental site trophoblastic tumor; the patient then underwent surgery. Placental site trophoblastic tumor is the rarest form of gestational trophoblastic disease, derived from intermediate trophoblast cells. It does not have a pathognomonic appearance; therefore, correlation with medical history, as well as results of laboratory tests and pathological analysis is mandatory. It is a relatively chemoresistant tumor, posing considerable therapeutic challenges; patients with localized disease are managed with surgery and those with metastatic disease require additional chemotherapy. Herein, we review the main features of this entity and top differential diagnosis, as the rarity of this tumor is associated with imaging and pathological pitfalls, reinforcing the need for further experience in this field.

Keywords: Gestational trophoblastic disease; Magnetic resonance; Placental site trophoblastic tumor; Ultrasound; Uterus.

Figure 1

Ultrasonography images of the uterus of a 34-year-old female patient with placental site trophoblastic tumor. Transabdominal sonography with a 5-MHz curvilinear probe, midline sagittal transabdominal view (1A); and transvaginal sonography with a 10-MHz endocavitary probe, midline sagittal view (1B) depict an acutely retroverted uterus measuring 90×67×45mm in the longitudinal longitudinal, transverse and antero-posterior axes, with diffuse heterogeneous myometrial echotexture and hematometra distending the endometrial cavity. Note the irregular contour of the endometrial cavity in the fundus region (white arrow).

Figure 2

Pelvic magnetic resonance images of a 34-year-old female patient with placental site trophoblastic tumor. Axial T1-weighted image (2A) reveals hyperintense filling of the endometrial cavity related to the presence of blood (white arrow). Axial oblique (perpendicular to the long axis of endometrial cavity) (2B) and sagittal (2C) T2-weighted images reveal heterogeneous hypersignal of the myometrium of the uterine corpus (asterisk), with loss of the zonal anatomy (white arrowhead). On a sagittal T1-weighted dynamic contrast-enhanced MR image obtained 2 minutes after contrast medium injection (2D), the tumor enhances to a lesser degree (white circle) than the normal cervix. [Philips Intera Pulsar 1.5T: T1-weighted images (TR=566; TE=10); T2-weighted images (TR=3500; TE=90); Dynamic contrast-enhanced MR image obtained with a three-dimensional gradient-recalled echo T1-weighted sequence (TR=5.6; TE=2.8), with fat suppression and after the administration of 0.1mmol/kg of gadopentetate dimeglumine at a rate of 2mL/sec acquired 2 minutes after injection].

Figure 3

Diffusion-weighted magnetic resonance (MR) images of the uterus of a 34-year-old female patient with placental site trophoblastic tumor. In the axial diffusion-weighted MR image (b=1000sec/mm²) (3A), the tumor shows high signal intensity with deep myometrial invasion (black asterisk). In the axial apparent diffusion coefficient (ADC) map (3B), the area of high signal intensity in the diffusion-weighted MR image shows low signal intensity, a finding that is consistent with restricted diffusion (white asterisk). Note the high intensity of the endometrial cavity in the diffusion-weighted MR image (black arrowhead) and the corresponding low intensity on the ADC map (white arrowhead) related to the presence of blood products causing marked restriction. [Philips Intera Pulsar 1.5T: Axial diffusion-weighted images (TR=2500; TE=70,9); flip angles of 90°, performed with b values of 1000sec/mm²].

Figure 4

Specimen obtained from the uterus of a 34-year-old female patient with placental site trophoblastic tumor. Macroscopic pathologic features (4A, 4B) reveal an infiltrating yellowish-white tumor with irregular contours that invades the whole thickness of the myometrium and projects into the endometrial cavity, without reaching the cervix. The tumor margin (yellow demarcation line in 4B) does not extend to the uterine serosa.

Figure 5

Sample of the uterus of a 34-year-old female patient with placental site trophoblastic tumor. [Photomicrograph showing intermediate trophoblastic cells with abundant eosinophilic cytoplasm and moderate nuclear pleomorphism, which deeply invades the myometrium. Hematoxylin and eosin stain, magnification: 5× (5A) and 10× (5B)].