Natural History of Fetal Non-Nuchal Lymphatic Malformations: A Single Center Retrospective Study.

OBJECTIVE

To document the natural history and complications of second- and third-trimester non-nuchal lymphatic malformations (LM) and identify predictors of these complications.

METHODS

We conducted a single-centre retrospective review of fetuses diagnosed with LMs between January 2015 and January 2024. Lesion size was quantified using the lymphatic malformation volume ratio (LVR): LVR = 0.523 x width x length x height (cm3) / head circumference (cm). Outcomes and LVR growth trends were analyzed using Student's t-test and a linear mixed-effects model.

RESULTS

Eighteen cases were included (10 cervical, 8 axillary). Uncomplicated cervical LMs grew at 0.3 cm2/week (p < 0.001). Intralesional bleeding (n = 3) was associated with LVR > 11 cm2 and significantly higher growth rates (2.6 vs. 0.3 cm2/week; p = 0.005). All cases with LVR > 5 cm2 required subsequent tracheostomy after birth. Axillary LMs grew at 0.21 cm2/week. One case with bleeding had LVR 4.4 cm2. Median LVR was significantly lower in vaginal deliveries compared with complicated births (2.0 vs. 7.3 cm2; p = 0.03). All LVR > 4 cm2 led to delivery complications.

CONCLUSION

Higher LVR predicts haemorrhage and airway intervention in cervical LMs, and delivery complications in axillary LMs. These exploratory observations warrant confirmation in larger prospective cohorts.