PEDIATRICS

J Neurosurg Pediatr  Volume 15 • January 2015

case rePortJ Neurosurg Pediatr 15:89–91, 2015

Fetal ovarian cyst mimicking a CSF pseudocyst in the setting of shunt failureMark calayag, MD,1 christian cantillano Malone, MD,2 Brian Drake, MB Bch Bao,2 Govind chavhan, MD,3 and James t. rutka, MD, PhD, Frcsc2

1Division of Neurosurgery, Albany Medical Center, Albany, New York; and Divisions of 2Neurosurgery and 3Radiology, The  Hospital for Sick Children, The University of Toronto, Ontario, Canada

Fetal ovarian cysts are common congenital lesions encountered in the neonatal population. These cysts are typically benign and rarely require any invasive intervention. Abdominal pseudocyst formation as a result of a ventriculoperitoneal shunt is a relatively infrequent occurrence and is similarly an uncommon cause of shunt failure. The authors present the case of a 4-month-old girl with shunted hydrocephalus who presented with shunt failure from a suspected abdominal pseudocyst that was found to be a fetal ovarian cyst.http://thejns.org/doi/abs/10.3171/2014.9.PEDS149Key WorDs fetal ovarian cyst; abdominal pseudocyst; ventriculoperitoneal shunt; hydrocephalus

The formation of an intraabdominal fluid collection at the distal end of a functioning ventriculoperito-neal (VP) shunt is somewhat rare and can be found

in the setting of shunt failure. These collections are typi-cally referred to as pseudocysts, and are usually associat-ed with shunt infection. Such pseudocysts are frequently associated with shunt malfunction. In this paper we pre­sent a case of an infant who presented with a potential shunt malfunction, and was found to have a fetal ovarian cyst mimicking a pseudocyst.

case reportHistory and examination

The patient was born preterm as a twin at 25 weeks gestational age. Her early neonatal course was compli-cated by Escherichia coli sepsis and meningitis, with the subsequent development of postinfectious hydrocephalus requiring a right occipital VP shunt at 11 weeks of age. Placement of the peritoneal catheter was performed lapa-roscopically, and no intraabdominal issues were reported at that time. She then presented at 4 months of age with a 5­day history of lethargy and emesis. On examination, there was a slight upward gaze preference (which was her baseline), an increased head circumference, and a bulg-ing fontanelle. There was slight dullness to percussion on abdominal examination, but the abdomen was otherwise soft and not tender, with no peritoneal signs. The patient exhibited breast budding and growth of pubic hair.

An MR image of the brain revealed acute hydrocepha-lus with an encysted left temporal horn (Fig. 1). The tem-poral horn cyst was not observed on previous imaging and was believed to have developed because of her previ-ously treated meningitis. An MR image of the abdomen was obtained that demonstrated a large, well­defined cyst measuring 5.3 × 3.7 × 4.4 cm3 in the right lower quad-rant adjacent to the right ovary. There was another 3.4 × 2.8 × 2.2 cm3 well­defined daughter cyst found within the larger cyst. Multiple loops of the peritoneal catheter were noted adjacent to the larger cyst, while the tip of the cath-eter was located in the left lower quadrant with minimal free fluid surrounding it (Fig. 2). The radiological diag-nosis was that of an ovarian cyst given the presence of a daughter cyst; a CSF pseudocyst was believed to be less likely (Fig. 3). Subsequent workup included CSF cultures, which were held for 5 days, from both the VP shunt and ultrasonography­guided aspiration of the abdominal cyst. These cultures were found to be negative for infection or malignancy. Benign mesothelial cells were identified on the abdominal cyst aspirate, which helped distinguish this cyst from a CSF pseudocyst, and along with the radiologi-cal characteristics, confirmed the diagnosis of an ovarian cyst.

operation and Postoperative courseFrom a neurosurgical perspective, the patient clinically

had signs of shunt malfunction; distal obstruction related

aBBreviatioN VP = ventriculoperitoneal.suBMitteD January 8, 2014.  accePteD September 22, 2014.iNcluDe WHeN citiNG Published online October 24, 2014; DOI: 10.3171/2014.9.PEDS149.Disclosure The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

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M. calayag et al.

J Neurosurg Pediatr  Volume 15 • January 2015

to the ovarian cyst was believed to be possible, but un-likely. Given the dilated ventricular system and encysted temporal horn, it was felt that she would benefit from an endoscopic fenestration of the cyst within the left tempo-ral horn, as well as an endoscopic third ventriculostomy; these were performed on Day 3 after admission. Because the CSF cultures from the VP shunt were negative for in-fection, the shunt hardware was not removed. CSF sent for microbiology assessment at the time of ventricular endoscopy was cultured for 5 days and was negative for infection. Unfortunately, the volume of fluid drawn from the abdominal cyst was inadequate for hormone analysis. Serum alpha­fetoprotein and estradiol were highly con-sistent with a functioning ovarian cyst. The gynecology service was consulted and a conservative approach was suggested. The patient recovered well postoperatively and she was eventually discharged, clinically improved, on postoperative Day 3. A postoperative MR image and CT scan showed adequately decompressed ventricles.

DiscussionFetal ovarian cysts are the most common, prenatally

diagnosed intraabdominal cysts,3 comprising approxi-mately 5% of all intraabdominal masses diagnosed in females shortly after birth.5 The exact etiology of these cysts is not known, but their pathogenesis is likely endo-crinological in origin. As reviewed by Akın et al.,1 there is an increased incidence of fetal ovarian cysts among pregnancies complicated by diabetes, preeclampsia, and Rhesus factor incompatibility, attributed to the increased

levels of placental chorionic gonadotropin levels that ac-company these conditions. Furthermore, fetal hypothy-roidism, congenital adrenal hyperplasia, and ovarian hy-perstimulation observed in premature infants have been implicated in ovarian cyst formation.1

Fetal ovarian cysts are simple, benign cysts, which typically resolve during the perinatal period in more than

FiG. 1. Axial FLAIR MR image of the brain shows hydrocephalus with an encysted left temporal horn (asterisk). FiG. 2. Abdominal radiograph of the shunt series (a) shows multiple 

loops of the VP shunt in the right lower abdomen (arrows) with its tip in the left lower quadrant. Coronal T2-weighted MR image (B) shows a large cyst (C) within the loops of the VP shunt (arrows). Axial postcon-trast T1-weighted MR image (c) shows a daughter cyst (DC) within the larger cyst (C). Arrows indicate loops of the VP shunt.

FiG. 3. Ultrasound image of the abdomen shows the cyst (C) and the daughter cyst (DC) within it.

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Fetal ovarian cyst and csF pseudocyst

J Neurosurg Pediatr  Volume 15 • January 2015

half of the cases.1,10 Histologically, these cysts are lined by benign mesothelial cells, which in our case helped to dif-ferentiate it from a CSF pseudocyst, which lacks mesothe-lial cells.9 Once diagnosed, these cysts are monitored with serial ultrasonography examinations for changes in size, structure, or intracystic hemorrhage, which may lead to or be a sign of impending torsion, the most common com-plication associated with these cysts.4,15 Other potential complications include hydramnios and ascites.1 The dif-ferential diagnosis of a perinatal, cystic, intraabdominal mass is large and includes urachal, mesenteric, and omen-tal cysts, enteric duplication cyst, uncalcified meconium pseudocyst, cystic teratoma, neuroblastoma, lymphangio-mas, renal cystic dysplasia, hydrometrocolpos, intestinal obstruction, and anterior meningocele.2,7,11,14 There are no specific features for simple cystic lesions except for the presence of “daughter cysts” or a “cyst within a cyst” be-ing specific for an ovarian cyst. Another possibility for the cyst­within­a­cyst appearance is a hydatid cyst, which is extremely uncommon in infants.

A CSF pseudocyst is a rare but well­described compli-cation of VP shunts, with an incidence of 0.7%–4.5%.8,9,12 Pseudocysts typically arise between 3 weeks and 5 years after placement of the VP shunt, but have been reported to develop as long as 10 years after VP shunt implanta-tion.6,13 Patients typically present with abdominal pain, nausea, vomiting, fever, decreased appetite, and symptoms and signs of shunt failure. The etiology of pseudocyst for-mation is believed to be either a low­grade infection or an inflammatory reaction involving the peritoneum and intes-tinal serosa.16 This notion is supported by histopathological findings of nonepithelial fibrous tissue and granulomatous tissue lined within the pseudocyst and inflammation in the surrounding serosal surfaces.16 When a CSF pseudocyst is associated with an infection, Staphylococcus epidermidis, Staphylococcus aureus, and Propionibacterium acnes are the most commonly isolated pathogens.16 A review of the literature by Yuh and Vassilyadi16 demonstrated that the reported incidence of infection with a pseudocyst ranged between 8% and 100%. Treatment of a documented pseu-docyst in the context of a VP shunt typically consists of externalization of the peritoneal catheter for a period of time while treating the VP shunt infection with antibiotics, followed by repositioning of the distal catheter within the abdominal cavity. On occasion, image­guided percutane-ous drainage of the pseudocyst is indicated, especially if the cysts are large.

In most instances, the finding of a well­organized in-traabdominal fluid collection around a distal VP shunt catheter in the setting of clinical shunt failure has a rela-tively short differential diagnosis, including intraabdom-inal abscess or a sterile or infected pseudocyst. To our knowledge, this is the first reported description of a fetal ovarian cyst occurring in the context of a patient with an indwelling VP shunt presenting with shunt malfunction. The presence of a fetal ovarian cyst in such patients has implications for therapy that are different than those for patients with documented and infected pseudocysts.

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Sander S, et al: Fetal­neonatal ovarian cysts—their monitor-ing and management: retrospective evaluation of 20 cases and review of the literature. J Clin Res Pediatr Endocrinol 2:28–33, 2010

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13.  Rovlias A, Kotsou S: Giant abdominal CSF pseudocyst in an adult patient 10 years after a ventriculo­peritoneal shunt. Br J Neurosurg 15:191–192, 2001

14.  Sandler MA, Smith SJ, Pope SG, Madrazo BL: Prenatal diagnosis of septated ovarian cysts. J Clin Ultrasound 13:55–57, 1985

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author contributionsAcquisition of data: Calayag, Cantillano Malone, Drake, Chavhan. Analysis and interpretation of data: Rutka, Chavhan. Drafting the article: Calayag, Cantillano Malone. Critically revising the article: Rutka, Calayag, Cantillano Malone, Drake. Reviewed submitted version of manuscript: Rutka, Calayag, Cantillano Malone, Drake. Approved the final version of the manuscript on behalf of all authors: Rutka.

correspondenceJames T. Rutka, Division of Neurosurgery, The Hospital for Sick Children, 555 University Ave., Ste. 1503, Toronto, ON M5G 1X8, Canada. email: james.rutka@sickkids.ca.

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