FETAL SPLENIC CYST

Three mechanisms have been proposed (1):

• Involution of pluripotent cells in the splenic parenchyma during development with subsequent squamous metaplasia (most widely accepted theory).
• Inclusion of coelomic mesothelium during organogenesis.
• Invagination of the surface mesothelium.
• Dilatation of normal lymph spaces (1).

CLASSIFICATION

• True cysts (congenital splenic cysts comprise 25% of true cysts). These cysts have a cellular layer, and include vascular, serous and infectious cyts, congenital cysts and cystic neoplasms ,epidermoid, dermoid, hemangiomas and lymphangiomas),
• Pseudocysts or false cysts have a fibrous capsule and are usually inflammatory, degenerative or post-traumatic.

ULTRASOUND

• Seven previously antenatal reports (2,3).
• Simple splenic cyst (4), presents as an echolucent lesion in the spleen.

• Multiple splenic cysts in lymphangiomyomatosis (4).
• The majority of splenic cysts are benign and are not associated with fetal or infant compromise.
• Some cysts, however, enlarge and become symptomatic with a risk of post-traumatic rupture, hemorrhage and infection (5).

1. Ten cases of CSC have been diagnosed by prenatal sonography from 31 to 35 weeks’ gestation (6-10).

2. Okada et al. (11) report a case of a cystic lesion in the upper left quadrant of the fetal abdomen that was first observed at 17 weeks and they later confirmed the diagnosis of CSC. Only one case was managed surgically due to compression by progressive enlargement (10).

3. Yilmazer and Erden (5) described one infant with CSC diagnosed prenatally at 31 weeks, which had completely regressed by 7 months of age.

Post-natal ultrasound of the spleen

DIFFERENTIAL DIAGNOSIS

• Duodenal atresia.
• Duplication cyst of the stomach.
• Cyst in left lobe of the liver.
• Hydronephrosis.
• Renal cyst.
• Adrenal cyst.

REFERENCES

1. Burrig KF. Epithelial (true) splenic cysts. Am J Surg Pathol 1988;12:275-281.
2. Okada M, Hata T, Ariyuki Y et.al. Fetal splenic cyst: change in size and shape with advancing menstrual age. J Clin Ultrasound 1995;23:204-206.
3. Lopes MAB, Ruano R, Bundinski V et.al. Prenatal diagnosis of congenital splenic cyst: a case report. Ultrasound Obstet Gynecol 2001;17:439-441.
4. Lichman JP, Miller EI. Prenatal ultrasonic diagnosis of splenic cyst. J Ultrasound Med 1988;7:637-638.
5. Yilmazer YC & Erden A. Complete regression of a congenital splenic cyst. J Clin Ultrasound 1998; 26: 223–224
6. Lichman JP & Miller EI. Prenatal ultrasonic diagnosis of splenic cyst. J Ultrasound Med 1988; 7: 637–638
7. Stiller RJ, de Regt RH, Choy OG. Antenatal diagnosis of fetal splenic cyst: a case report. J Reprod Med 1991; 36: 320–322
8. Garel C & Hassan M. Foetal and neonatal splenic cyst-like lesions: US follow-up of seven cases. Pediatr Radiol 1995; 25: 360–362
9. Taso L & Jeanty P. Spleen, cyst. Fetus 1993; 3: 7–10
10. Todde G, Bagolan P, Fariello G et.al. Epidermoid cyst of the spleen in a newborn infant. Prenatal diagnosis and partial splenectomy. Chir Pediatr 1989; 30: 172–174
11. Okada M, Hata T, Ariyuki Y et.al. Fetal splenic cyst: change in size and shape with advancing menstrual age. J Clin Ultrasound 1995; 23: 204–206