Successful Laparoscopic-Assisted Management of a Rare Purely Cystic Type IV Sacrococcygeal Teratoma in Neonate: A case report

Summary

Type IV sacrococcygeal teratomas (SCTs) are the rarest subtype of SCTs. We report a 2-week-old female who presented to a tertiary care centre in Muscat, Oman, in 2024 with abdominal distension and feeding intolerance. Imaging revealed a purely cystic presacral lesion, managed with successful laparoscopic-assisted cyst excision and coccygectomy. Histopathology confirmed a mature cystic SCT and the patient was diagnosed with a purely cystic Altman type IV SCT. The postoperative course was uneventful apart from minor wound dehiscence, which resolved with conservative management. Follow-up showed complete wound healing and no recurrence. Purely cystic Type IV SCTs are extremely rare and challenging to diagnose due to their benign radiological appearance and lack of external manifestations. Complete surgical excision with coccygectomy remains the cornerstone of treatment; laparoscopic-assisted excision in neonates is feasible and safe.

1. Introduction

Sacrococcygeal teratomas (SCTs) are congenital germ cell tumours arising from pluripotent cells of the primitive streak, incorporating tissues from all 3 embryonic germ layers (ectoderm, mesoderm and endoderm). They represent the most common solid tumour in neonates and the most frequent extragonadal germ cell tumour in children, with an estimated incidence of approximately 1 in 35,000–40,000 live births.¹ The female-to-male predominance is approximately 3:1 to 4:1.²

SCTs are classified according to the Altman system into 4 types based on their anatomical extent: type I (predominantly external with a small presacral component), type II (external with significant intrapelvic extension), type III (predominantly intrapelvic with a small external component) and type IV (entirely intrapelvic with no external component).³ Type IV SCTs—completely internal and located presacral—are the rarest subtype, accounting for only approximately 10% of all SCTs and are associated with late presentation due to the absence of a visible external mass.^4,5

Histologically, SCTs may be classified as mature (benign), immature or malignant. With respect to tissue composition, lesions may be solid, mixed or purely cystic; purely cystic SCTs account for only approximately 15% of all SCTs.⁶ The distinction of the purely cystic subtype is of considerable clinical importance as their entirely fluid-filled architecture renders them radiologically subtle and liable to be misdiagnosed as other benign presacral lesions such as tailgut cysts, rectal duplications or anterior meningoceles. Consequently, prenatal detection rates are substantially lower for purely cystic type IV SCTs than for their solid or mixed counterparts, and postnatal diagnosis is frequently delayed until the tumour reaches sufficient size to cause compressive symptoms.⁶ Despite their deceptively benign appearance, complete excision including coccygectomy remains mandatory given the risk of malignant transformation and recurrence.³

We report a rare case of a purely cystic Altman Type IV SCT diagnosed in a 2-week-old neonate managed successfully through a laparoscopic-assisted approach.

2. Case report

A 2-week-old full-term female, born via spontaneous vaginal delivery to a mother with a solitary kidney, presented to the emergency department of a tertiary care centre in Muscat, Oman, in 2024 with a 3-day history of progressive abdominal distension, non-bilious vomiting (3–4 episodes/day) and excessive crying. There were no antenatal complications and prenatal imaging was unremarkable. The baby had passed meconium on day 1 and did not require neonatal intensive care unit admission.

On examination, the patient was alert but irritable. Vital signs revealed a temperature of 37.5°C, heart rate of 210 bpm, respiratory rate of 42 breaths/min, oxygen saturation of100% on room air, blood pressure of 78/66 mmHg and weight of 3.6 kg. Mild to moderate dehydration was noted. The abdomen was distended, tense and non-tender. Genitalia examination was normal with 3 separate openings and a patent vagina. Digital rectal examination revealed a posterior presacral mass.

Laboratory investigations were normal apart from evidence of acute kidney injury (AKI) with elevated creatinine and urea (creatinine = 191 μmol/L, urea = 12.8 mmol/L). Urine culture was positive for extended-spectrum beta-lactamase producing Escherichia coli. Tumour markers were within normal limits for the patient's age (alpha-fetoprotein [AFP] = 3,780 ng/mL, β-hCG <0.1 IU/L, lactate dehydrogenase = 447 U/L, CA-125 = 14 U/mL). Renal impairment was attributed to obstructive uropathy secondary to mass effect, which improved after Foley catheterisation. Paediatric nephrology was consulted for AKI management.

The initial ultrasound demonstrated a large unilocular cystic mass in the abdominopelvic region causing bilateral hydronephrosis, along with a right femoral hernia. Repeat ultrasound post-catheterisation revealed a cystic lesion posterior to the uterus and bladder. Magnetic resonance imaging (MRI) demonstrated a 7 × 3.9 × 3.8 cm presacral cystic mass without bony sacrococcygeal defect, raising suspicion for a tailgut cyst or purely cystic SCT [Fig. 1].

Fig. 1.

Preoperative magnetic resonance imaging of the pelvis of a 2-week-old female. A, B and C demonstrate cross-sectional T2-weighted sequences showing a well-defined, homogeneously hyperintense, unilocular cystic presacral mass measuring 7.0 cm (craniocaudal) × 3.9 cm (anteroposterior) × 3.8 cm (transverse), located posterior to the uterus and bladder and anterior to the sacrum, consistent with a purely cystic Altman type IV sacrococcygeal teratoma. No sacrococcygeal bony defect or intraspinal extension was identified. D Illustrates the same findings in a sagittal plane.

Considering the entirely internal component of the lesion, a decision was made to commence with an abdominal approach via laparoscopy and, if intraoperative findings confirmed an SCT, to reposition the patient in the prone position to access the coccyx. A diagnostic laparoscopy was initiated via a 5-mm umbilical port, which revealed a cystic lesion located posterior to the uterus, distinct from the rectum and arising from the posterior pelvic wall; 2 additional 3-mm ports were placed under direct vision in the right and left abdomen. Complete laparoscopic mobilisation of the intra-abdominal component of the cyst was performed, carefully dissecting it from its lateral attachments to the pelvic wall and its anterior relation to the rectal mesentery. To enhance visualisation, controlled decompression was achieved using a laparoscopic aspiration needle, which further delineated the cyst's extension into the presacral space. At this stage, the patient was repositioned prone and the remaining lesion was excised through a posterior sagittal approach. A midline posterior incision was made, the coccyx was identified and complete excision of the residual cyst was carried out along with a coccygectomy. The specimen was delivered intact through the posterior sagittal incision. No abdominal drain was placed and the procedure was completed uneventfully without complications or significant blood loss.

The neonate was monitored in the high dependency unit for 24 hours and subsequently transferred to the ward. She had an uneventful hospital stay apart from mild serous discharge from the posterior sagittal incision that resolved spontaneously; the patient was discharged on postoperative day 7. On day 12 post-operatively, she represented with mild wound dehiscence of the posterior sagittal incision without signs of infection and was managed conservatively with wound care. Follow-up at 3 weeks and 3 months were unremarkable, with normalisation of renal function confirmed at 3 months. The patient was subsequently reviewed at 1-year and 2-year follow-up appointments. Clinically, there was no evidence of local recurrence at either visit. Urinary and bowel function remained normal. AFP measured at 20-months post-operatively was less than 5 ng/mL, well within the normal range for age, providing further reassurance against occult recurrence or malignant transformation. Assessment of continence function was deferred, as the patient remains too young for reliable evaluation at this stage of development.

The excised lesion showed features consistent with a mature SCT (prepubertal type). Microscopy revealed multiple epithelial types (serous, respiratory, squamous), mature cartilage, pancreatic acini and fibroconnective tissue. No immature or malignant elements were identified. Synaptophysin staining was negative for neuroepithelial differentiation [Fig. 2]. The final diagnosis was mature (benign) purely cystic type IV SCT.

Fig. 2.

Haematoxylin and eosin staining of the excised lesion demonstrating mature elements from all 3 germ layers: (A) Serous (arrow) and respiratory-type (arrowhead) epithelium; (B) Mature hyaline cartilage (arrow); (C) Pancreatic acinar tissue and fibroconnective stroma (arrow). No immature or malignant components were identified. Synaptophysin immunostaining (D) was negative, excluding neuroepithelial differentiation (arrow). Panel B is at × 40 magnification while the remaining panels are at × 100.

3. Discussion

SCTs arise from pluripotent cells of the primitive streak, incorporating tissues from all 3 germ layers.⁷ Their histological diversity gives rise to a wide spectrum of presentations—solid, cystic or mixed—with purely cystic types accounting for approximately 15% of all SCTs.⁶ According to the Altman classification, type IV SCTs are entirely presacral with no external component and account for only approximately 10% of all SCTs.³ A purely cystic presentation of type IV SCT, as observed in the current patient, is exceedingly rare. Winderl and Silverman described only 2 prior cases, neither of which remained purely cystic at follow-up, in addition to their own case.⁶ To the best of the authors’ knowledge, the current case represents one of the few documented instances of a persistently cystic, completely internal presacral SCT diagnosed in the neonatal period due to obstructive symptoms [Table 1].^6,8,9,10

Table 1.

Summary of reported cases of Altman type IV sacrococcygeal teratoma in the neonatal and paediatric literature, including the present case.^6,8,9,10

Author and year of publication	Tumour character (Altman classification)	Surgical approach	Outcome	Follow-up
Winderl and Silverman6 (1997)	Altman type IV SCT — completely cystic presacral mass (prenatal diagnosis)	Open abdominoperineal approach with excision of cyst and coccyx	No residual medical complication	6 months
Jumbi et al.8 (2018)	Altman type IV SCT — completely cystic presacral mass; urinary retention; bilateral hydronephrosis	Combined open abdominal and posterior sacral approach with excision of cyst and coccyx	Complete resection; full resolution of urinary symptoms	Ongoing
Jumbi et al.8 (2018)	Altman type IV SCT — presacral mass with mixed cystic and solid component	Combined open abdominal and posterior sacral approach	Complete resection; histology: immature teratoma	Ongoing
Eftekharzadeh et al.9 (2016)	Altman type IV SCT — large presacral mass with mixed cystic and solid components (144 × 63 mm); urinary retention and bladder displacement	Posterior sagittal approach followed by anterior abdominal midline approach	Complete resection; mature cystic SCT; normal voiding and bowel function preserved	18 months
Wessell et al.10 (2018)	Altman type IV SCT — cystic presacral mass (13.2 × 9.7 × 9.6 cm) with intraspinal extradural extension through S4 neuroforamen (2-month-old infant)	Posterior-anterior-posterior three-stage approach with coccygectomy	Gross total resection; no residual tumour; histology: mature cystic teratoma; normal neurological and urinary function	17 months
Present case (2024)	Altman type IV SCT — purely cystic presacral mass (7 × 3.9 × 3.8 cm); 2-week-old neonate; urinary obstruction and bilateral hydronephrosis	Laparoscopic mobilisation of intra-abdominal component followed by posterior sagittal approach with coccygectomy	Complete resection; histology: mature (benign) SCT; AKI resolved by 3 months; AFP <5 ng/mL at 20 months; no clinical recurrence; normal urinary and bowel function at 2 years; continence assessment deferred (too young)	2 years (ongoing)

SCT = sacrococcygeal teratoma; AKI = acute kidney injury; AFP = alpha-fetoprotein.

These tumours are generally benign in neonates; however, malignancy occurs in 7–13% of cases, with risk increasing in the presence of solid components or when excision is delayed.¹¹ Large tumour size (>10 cm) and rapid intrauterine growth increase perinatal risks such as preterm labour, tumour rupture or fetal demise.^3,11

While prenatal diagnosis is possible via ultrasound as early as 22 weeks of gestation, purely cystic or deeply located lesions are frequently missed prenatally, as in the current case. The initial presentation may involve abdominal distension, urinary obstruction or bowel dysfunction—highlighting the importance of a broad differential diagnosis for neonatal pelvic masses.¹² The absence of an external mass in type IV SCTs makes early diagnosis particularly challenging, underscoring the necessity for a high index of clinical suspicion in any neonate presenting with unexplained abdominal distension, hydronephrosis or a palpable presacral mass on digital rectal examination.^2,8

MRI is the preferred imaging modality for characterisation and preoperative planning, providing superior delineation of the tumour's relationship to adjacent pelvic structures compared with ultrasound or CT.⁹ Early diagnosis is paramount as diagnostic delay not only increases the risk of compressive complications—as demonstrated by the AKI encountered in this case—but also raises the probability of malignant transformation, particularly for lesions with solid components.^3,11 Prompt surgical intervention is therefore essential once the diagnosis is established.

Complete excision including coccygectomy remains the cornerstone of management, as preservation of the coccyx has been associated with recurrence rates of up to 37%.³ The introduction of minimally invasive surgery (MIS) has transformed the surgical approach to these lesions. Laparoscopy provides enhanced magnification and superior visualisation within the confined pelvic domain, facilitates precise dissection of the tumour from adjacent viscera and reduces surgical trauma and postoperative morbidity compared with open approaches.¹⁰ In the current case, laparoscopic mobilisation of the intra-abdominal component, followed by repositioning to a prone position for posterior sagittal resection and coccygectomy, allowed for complete excision in a 2-week-old neonate without complications. To the best of the authors’ knowledge, this case report represents the youngest patient reported in the literature to be managed successfully through this combined minimally invasive approach. The feasibility of laparoscopic-assisted resection in such small neonates is encouraging and supports the adoption of MIS as the preferred strategy in specialised centres with appropriate expertise.

Several limitations of this case report merit acknowledgement. First, as a single case report, the findings and surgical approach described cannot be generalised and conclusions regarding superiority of any one technique must be drawn cautiously. The rarity of purely cystic type IV SCTs in the neonatal period precludes large-scale comparative studies and the existing literature consists almost exclusively of isolated case reports and small case series. Second, the current follow-up period is 2 years. While clinical and biochemical findings at this point are reassuring, longer-term surveillance data remain limited. Continence function cannot yet be formally assessed given the patient's age and ongoing follow-up is required to fully characterise long-term bowel, bladder and continence outcomes. Recurrence and malignant transformation may occur years after apparently complete resection and continued surveillance with serial AFP monitoring and clinical review is essential.¹³ Finally, the tumour's small size relative to other reported cases may have contributed to the feasibility of a minimally invasive approach and the applicability of this technique to larger or more complex lesions remains to be established.

4. Conclusion

Purely cystic type IV SCTs diagnosed in the neonatal period are exceedingly rare and present considerable diagnostic challenges owing to the absence of an external component and their radiological resemblance to other benign presacral lesions. A high index of clinical suspicion, prompt MRI evaluation and early surgical intervention are essential to prevent compressive complications and minimise the risk of malignant transformation. Laparoscopic-assisted complete excision with coccygectomy is a feasible, safe and effective approach in neonates, offering enhanced visualisation within a limited pelvic domain while minimising surgical trauma and postoperative morbidity. This case highlights the practicality of a minimally invasive technique in managing this uncommon neonatal presentation and underscores the need for long-term oncological surveillance in all patients following resection of SCT.

Authors’ Contribution

Alghalya Khalid Almaawali: Conceptualization, Writing – Original Draft, Writing – Review & Editing, Visualization, Project Administration, Investigation. Ahmed Alwahaibi: Conceptualization, Writing – Original Draft, Writing – Review & Editing, Formal Analysis, Data Curation, Investigation. Yousuf Al-Shaqsi: Investigation, Resources, Writing – Review & Editing. Farman Laghari: Investigation, Resources, Writing – Review & Editing. Bashar Dawud: Investigation, Resources, Writing – Review & Editing. Marwa Al-Riyami: Supervision, Validation, Writing – Review & Editing.

Ethics Statement

The patient's parents provided written informed consent for the publication of this case and accompanying images.

Conflict of Interest

The authors declare no conflicts of interest.

Funding

No funding was received for this study.

Data Availability

Data as well as a copy of the written informed consent are available upon reasonable request from the corresponding author.