4.4x4.2

[Earlie Schwoyer]

Amixed gestational trophoblastic neoplasia (GTN) is a very rare, histologically heterogeneous form of tumour, generally made up by choriocarcinoma and/or placental site trophoblastic tumour (PSTT) and/or epithelioid trophoblastic tumour (ETT) [1-3].

GTN present in women during the reproductive age and very rarely after menopause, generally with irregular metrorrhagia, weeks, months or years after a regular pregnancy, spontaneous miscarriage or voluntary termination; sometimes, GTNs might present with unexplained metastases, which often affect the lungs, in the weeks and months after normal childbirth or ectopic pregnancy [1].

A 34 year-old Caucasian woman was referred to our Obs/Gyn division, presenting with unexplained metrorrhagia, almost 4 months after normal childbirth. All laboratory tests were unremarkable, except for elevated serum β-HCG (4333 IU/L) and CA-125 levels (366 KU/L). The patient was then referred to our Radiology unit, for a Chest X-ray and abdominal ultrasound evaluation; a dishomogeneously hypoecoic uterine mass (4.4x4.2 cm, Figure 1) was noted. Except for this finding, the initial imaging tests were otherwise unremarakable. The patient was immediately scheduled for a contrast-enhanced Pelvic MRI evaluation, that confirmed the presence of a dishomogenous, irregularly round mass (4.5x4.3x3.6 cm, Figures 2-5), in the endometrial cavity but protruding outwards, eroding the myometrium, the latter barely recognisable at the right lateral aspect of the uterine fundus. The post-contrast acquisitions showed the mass to be highly vascular, almost reaching the outlying sierosa.

Figure 2. MRI Axial pre-contrast fat-sat T1 weighted sequence shows a rounded, dishomogeneously intense mass within the endometrial cavity; hyperintense spots within and around the mass are suggestive for haemorrhage. Infiltration of the right cranial aspect of the fundic myometrium is noted

Figure 3. MRI Axial post-contrast fast-sat T1 weighted sequence shows dishomogeneous enhancement of the mass, which is prevalently peripheral. Enhancement spots within the mass are found, too

Figure 4. MRI Diffusion weighted images (DWI) show hyperintense spots within the mass, highly suggestive for pathologic hypercellularity. The vast majority of the mass is hypointense, due to the high presence of necrosis. No pathologic lymph nodes are found

Figure 5. MRI Sagittal post-contrast fat-sat T1 weighted sequence clearly shows peripheral contrast enhancement and the infiltration of the right cranial aspect of the fundic myometrium

After multidisciplinary evaluation, considering the clinical history and recent pregnancy, the unexplained, high serum β-HCG levels and the MRI findings, a diagnosis of gestational trophoblastic neoplasia, namely PSST, was suspected.

The patient was then scheduled for a Total Body CECT, which was carried out three days later, to rule out the presence of distant disease. The pelvic findings were, of course, totally confirmed; a slight increase in vascularization was noted, albeit the MRI exam was executed only three days before. Even though abdomen, pelvis and head, except for the mass, were completely unremarkable, the presence of small (60), rounded lung nodules, compatible with metastases, was noted.

Ki-67 replication index was 30% for the first set of nodules, and 90% for the latter. The two histological patterns were respectively compatibile with PSTT and choriocarcinoma, which combine to form a mixed gestational trophoblastic neoplasia (Figures 6-9).

Figure 6. Post-contrast arterial phase CT appearance of the mixed PSTT/Choriocarcinoma GTN. Intense peripheral contrast enhancement of the mass, with infiltration of the myometrium towards the sierosa

Figure 8. Pathologic features of the mixed PSTT/Choriocarcinoma GTN. The presence of plurinucleated elements with clear cytoplasm is suggestive for syncytiotrophoblast and choriocarcinoma. Haemorrhage, necrosis are noted too

Figure 9. Pathologic features of the mixed PSTT/Choriocarcinoma GTN. Clusters of moderately pleiomorphic, mononucleated elements suggestive for intermediate trophoblast and PSTT, with a high mitotic index (>5 mitoses/field)

Even though pure and mixed GTNs are a quite rare disease, the presence of vaginal bleeding/metrorrhagia, plus elevated serum β-HCG, should prompt the suspect in the differential. Pelvic, contrast-enhanced MRI is the method of choice for regional disease staging; total-body CECT should always be added, too, to exclude the spread of the disease to distant sites, especially to the lungs. Treatment can be by hysterectomy only or by hysterectomy plus chemotherapy, when in presence of metastases or in selected, high-risk patients with local disease.

2021 Fontanella G. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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