Prenatal diagnosis of abdominal aortic aneurysm with pseudoaneurysm

A 34-year-old woman was referred to our hospital at 24+4 weeks of gestation for further evaluation of two cystic masses in the fetal abdomen. The patient had a history of antiphospholipid syndrome and was receiving aspirin for anticoagulation. No other medications were taken during organogenesis. Noninvasive DNA screening for Down syndrome yielded negative results. Whole exome sequencing and chromosome analysis revealed no abnormalities, and there was no family history of congenital anomalies. The upper pulsatile mass measured 41×35×30 mm and was located below the diaphragm and above the renal artery in the descending aorta. It exhibited characteristics consistent with a true aneurysm, such as a smooth wall, a wide communication with the descending aorta, and swirling blood flow within the cystic mass without a biphasic flow spectrum ([Fig. 1]A–C). The distal mass measured approximately 22×10×11 mm and was located below the renal artery. It exhibited a laceration approximately 5.3 mm wide between the mass and the abdominal aorta. Based on its irregular wall structure, uneven echogenicity, narrow laceration with the descending aorta, and the presence of a biphasic flow spectrum, we identified the lower mass as a pseudoaneurysm. A small normal arterial course was observed between these 2 masses.

Fig. 1 Prenatal and postnatal ultrasonographic imaging. A–C At 24+4 weeks of gestation, D–F Postnatal imaging. Two cystic masses were observed to communicate with the abdominal aorta. A, B Two-dimensional ultrasound: The upper mass displayed a smooth wall and wide communication with the DAO, while the lower mass exhibited an irregular wall, uneven echo, and narrow interference with the DAO. C Color Doppler ultrasound: Biphasic flow spectrum was detected only in the lower mass during dynamic observation (yellow arrows). D, E The size of both cystic masses had increased compared to previous measurements, and there was part of the normal abdominal aorta (arrows) between them. F Discontinuity of the vessel wall was noted, with approximately 5.3mm of communication between the lower cystic mass and the abdominal aorta. (DAO: descending aorta, RCIA: right common iliac artery, LCIA: left common iliac artery, H: heart, ST: stomach).

Upon follow-up, both masses were found to be enlarged. The patient opted for pregnancy termination, and at 26 +6 weeks of gestation, she delivered a stillborn male fetus vaginally. Postnatal ultrasound findings were consistent with the prenatal diagnosis ([Fig. 1]D–F).

The autopsy revealed no other congenital anomalies, except for those involving the cardiovascular system. Notably, the celiac trunk and superior mesenteric artery were absent from their usual positions ([Fig. 2]A). The vessel wall showed continuity between the descending aorta and the abdominal aortic aneurysm (AAA) ([Fig. 2]B), and prominent vessels were observed along the AAA wall ([Fig. 2]C). A segment of normal descending aorta was present between the AAA and the pseudoaneurysm ([Fig. 2]D). Pathological findings of the AAA included: (1) thickened vessel wall ([Fig. 3]C), (2) infiltrated inflammatory cells ([Fig. 3]C), (3) an increased number of larger vessels ([Fig. 3]C), (4) sparse endothelial cells and intima exudation, with few internal elastic membranes ([Fig. 3]D), (5) thinning and disarray of elastic fibers, along with thickened and disordered collagen fibers ([Fig. 3]I, J), and (6) thinning of the media layer with disordered and reduced muscle fiber content ([Fig. 3]I, J). Pathological findings of the pseudoaneurysm (PSA) included: (1) a higher number of inflammatory cells than in the AAA, with the formation of lymphoid follicles ([Fig. 3]E, F), (2) disrupted intima-media layers and disappearance of the 3-layer structure ([Fig. 3]K, L, [Fig. 4]A), and (3) thrombus formation ([Fig. 4]B).

Fig. 2 Postnatal anatomical diagram. A The abdominal aorta was isolated. B The vessel wall was continuous between the DAO and the AAA. C Large vessels are observed on the wall of the AAA. D There was a part of the normal DAO between the AAA and PSA. (H: heart, DAO: descending aorta, AAA: abdominal aortic aneurysm, PSA: pseudoaneurysm, RCIA: right common iliac artery, LCIA: left common iliac artery).

Fig. 3 HE and Van Gieson’s staining of the normal vessel wall, AAA, and PSA. A, C, E HE staining ×40. B, D, F HE staining ×100. G, I, K Van Gieson’s staining ×40. H, G, L Van Gieson’s staining ×100. A, B Normal abdominal aortic wall structure. C The vessel wall was thickened. The intima and media of the AAA were infiltrated by inflammatory cells (ellipse). The adventitia exhibited large nutrient vessels (blue arrows). D Only a small portion of the internal elastic membrane remained in the intima of the AAA (gray arrows), endothelial cells are sparse, and exudation is present in the intima. E, F In the PSA, the normal vessel wall structure is disrupted. Numerous inflammatory cells and lymphoid follicles (green arrows) were observed throughout the full thickness of the surrounding wall (ellipse). G, H In the normal vessel wall, the media layer contains abundant elastic fibers (black arrows), collagen fibers (red arrows), and muscle fibers (yellow arrows). I, J The media layer of the AAA was thinned, with disordered and significantly reduced muscle fibers (yellow arrows). Collagen fibers (red arrows) were increased, thickened, and disorganized, while elastic fibers (black arrows) were thin and irregular. K, L The intima-media membrane was disrupted, and the 3-layer structure disappeared. (AAA: abdominal aortic aneurysm, PSA: pseudoaneurysm).

Fig. 4 Van Gieson’s staining of a PSA. A Van Gieson’s staining ×10. B Van Gieson’s staining ×40. A Interruption of the vascular wall (arrows). B The thrombus formed in the middle of the PSA wall (dashed line). (PSA: pseudoaneurysm).

Publikationsverlauf

Eingereicht: 12. Juli 2024

Angenommen nach Revision: 24. Februar 2025

Artikel online veröffentlicht:
14. März 2025