Cystic Hygroma
A 23-Year-Old female at First-Trimester Ultrasound. Diagnosis? • Xray of the Week
Figure 1. Transabdominal first-trimester pelvic ultrasound. 23-year-old patient presenting with vaginal bleeding: Diagnosis?
Figure 2. A. Magnified sagittal-plane view of the cystic structure shows a thin, complete outer wall (red arrow) and an internal septation (yellow arrow) crossing the cyst; ultrasound calipers measure 1.6 x 1.2 cm. Fetal pole (green arrow) is seen with the cystic structure (yellow arrow) immediately dorsal to it, at the craniocervical junction (blue arrow). B. Calipers placed across the dorsal nuchal region measure an additional, smaller 0.5 cm focus, in keeping with a markedly thickened/septated nuchal translucency. Note the midline septum representing the nuchal ligament (white arrow).
Epidemiology
Fetal cystic hygroma is identified in approximately 1 in 285 pregnancies undergoing first trimester nuchal translucency screening, with an estimated overall prenatal prevalence of 0.2-3%. It is far less common as a postnatal diagnosis, with an incidence at birth of only about 1 in 6000, since most affected pregnancies end in miscarriage, intrauterine fetal death, or elective termination (1). A chromosomal abnormality is identified in roughly half of prenatally detected cases overall, most commonly monosomy X (Turner syndrome), trisomy 21, trisomy 18, and triploidy (2,3).
Clinical Manifestations
Cystic hygroma is usually an incidental finding on first- or early second-trimester sonography, typically identified as a markedly increased and septated nuchal translucency. Severe lymphatic obstruction may progress to nonimmune hydrops fetalis, with generalized skin edema, pleural or pericardial effusion, and ascites, a combination associated with a markedly worse outcome. If it persists after birth, it can present as a soft, compressible, transilluminant neck mass (1).
Pathology Cystic hygroma is a macrocystic lymphatic malformation resulting from failure of the paired jugular lymphatic sacs to establish normal communication with the internal jugular veins and the remainder of the venous system during the fifth to ninth week of gestation. The resulting obstruction causes progressive dilation of the sequestered sacs, producing thin-walled, multiloculated cystic spaces filled with proteinaceous lymphatic fluid within the posterior soft tissues of the fetal neck. Histologically, the cyst walls are lined by a single layer of flattened endothelium with scant surrounding stroma (1).
Classification Cystic hygromas are classified sonographically as septated or nonseptated, a distinction with direct prognostic importance. The nonseptated form is a simple, markedly thickened nuchal translucency without an internal dividing line. The septated form, as in this case, shows a midline septum representing the nuchal ligament, flanked by paired symmetric cystic spaces. This distinction carries prognostic weight: in one comparative series, septated lesions had a 72% aneuploidy rate, a 40% rate of hydrops, and only a 12% livebirth rate, compared with 5.7%, under 2%, and 94%, respectively, for nonseptated lesions (3). Pathologically, lymphatic malformations are further categorized by cyst size as macrocystic (individual cysts greater than 2 cm), microcystic (less than 2 cm), or mixed.
Radiographic Features
On prenatal ultrasound, cystic hygroma appears as a thin-walled, anechoic to hypoechoic cystic structure in the soft tissues dorsal to the fetal craniocervical junction, frequently traversed by one or more internal septa (Figures 1-2) (4). Caliper measurements are used to document lesion size and to distinguish it from a simple increased nuchal translucency. Color Doppler characteristically shows no internal flow. Postnatally, MRI is the modality of choice for defining the full extent and its relationship to adjacent neurovascular structures before surgical planning.
Treatment and Prognosis
Once identified, cystic hygroma warrants karyotype, microarray testing (chorionic villus sampling or amniocentesis), a detailed fetal anatomic and cardiac survey, and serial sonographic surveillance for hydrops. Prognosis is governed chiefly by septation status, karyotype, and the presence of hydrops (5,6); pregnancies reaching the second trimester without these adverse features generally do well. Postnatally, a persistent or isolated lymphatic malformation is managed with intralesional sclerotherapy as first-line treatment, with surgery reserved for lesions that fail sclerotherapy, recur, or threaten the airway; an ex utero intrapartum treatment (EXIT) procedure may be needed when a large lesion is expected to obstruct the airway at delivery (7).
Conclusion
Fetal cystic hygroma is an important early sonographic marker of aneuploidy and adverse pregnancy outcome. Its recognition should prompt genetic counseling, karyotype testing, and close sonographic follow-up.
References:
Rangel V, Having K. Cystic Hygroma. J Diagn Med Sonogr. 2008;24(4):218-222. DOI: https://doi.org/10.1177/8756479308319969
Malone FD, Ball RH, Nyberg DA, et al. First-trimester septated cystic hygroma: prevalence, natural history, and pediatric outcome. Obstet Gynecol. 2005;106(2):288-294. DOI: 10.1097/01.AOG.0000173318.54978.1f
Bronshtein M, Bar-Hava I, Blumenfeld I, Bejar J, Toder V, Blumenfeld Z. The difference between septated and nonseptated nuchal cystic hygroma in the early second trimester. Obstet Gynecol. 1993;81(5 ( Pt 1)):683-687. https://pubmed.ncbi.nlm.nih.gov/8469454/
Sepúlveda WH, Ciuffardi I. Early sonographic diagnosis of fetal cystic hygroma colli. J Perinat Med. 1992;20(2):149-152. DOI: 10.1515/jpme.1992.20.2.149
Chen HY, Zheng JQ, Zhang HP. A case report of Turner syndrome associated with fetal nuchal cystic hygroma and bilateral syndactyly of the hands and feet. Ital J Pediatr. 2019;45(1):85. Published 2019 Jul 18. DOI: 10.1186/s13052-019-0680-4
Rosati P, Guariglia L. Transvaginal ultrasound detection of septated and non-septated cystic hygroma in early pregnancy. Fetal Diagn Ther. 1997;12(3):132-135. DOI: 10.1159/000264452
Gowda M, Godipelli L, Gangadhar L, Jindal B, Deodar K, Yadav M. Management of isolated fetal lymphangiomas following prenatal diagnosis: case series. J Fetal Med. 2021;8(1):39-43. DOI: https://doi.org/10.1007/s40556-021-00288-5
Umaiza Ihsan, MD is a medical graduate of King Edward Medical University,
Pakistan. She completed her internship at Mayo Hospital, Lahore, including a three-
month rotation in Radiology, which further strengthened her interest in diagnostic
imaging. She has gained additional clinical exposure in Radiology through observerships at Mon Health Morgantown and the University of Maryland, Baltimore. She has a strong interest in Radiology, particularly diagnostic imaging and its role in clinical decision-making, and is actively interested in clinical research, with experience in systematic reviews and medical research.
Kevin M. Rice, MD is the president of Global Radiology CME and is a radiologist with Cape Radiology Group. He has held several leadership positions including Board Member and Chief of Staff at Valley Presbyterian Hospital in Los Angeles, California. Dr. Rice has made several media appearances as part of his ongoing commitment to public education. Dr. Rice's passion for state of the art radiology and teaching includes acting as a guest lecturer at UCLA. In 2015, Dr. Rice and Natalie Rice founded Global Radiology CME to provide innovative radiology education at exciting international destinations, with the world's foremost authorities in their field. In 2016, Dr. Rice was nominated and became a semifinalist for a "Minnie" Award for the Most Effective Radiology Educator. He was once again a semifinalist for a "Minnie" for 2021's Most Effective Radiology Educator by AuntMinnie.com. He has continued to teach by mentoring medical students interested in radiology. Everyone who he has mentored has been accepted into top programs across the country including Harvard, UC San Diego, Northwestern, Vanderbilt, and Thomas Jefferson.
Follow Dr. Rice on Twitter @KevinRiceMD
Comments