Fetal Testicular Teratoma: Report of a Prenatally Undiagnosed Case and Literature Review

Abstract

Background: Neonatal testicular teratoma is very rare. In addition, testicular teratoma diagnoses are usually missed during the relatively short neonatal period. We report the case of an infant with an undiagnosed testicular teratoma, who presented clinical signs during the prenatal and neonatal periods. We also reviewed the literature for ultrasonographic findings of prenatal and infancy testicular teratomas in an attempt to promote timely diagnoses and treatments for testicular teratomas.

Case presentation: A 29-year-old pregnant woman underwent a routine obstetric examination at 30w+2d of gestation. Doppler ultrasound examination revealed a cystic mass (30 × 26 × 26 mm) in the left lower abdomen of the fetus, next to the bladder. The inner wall of the cyst enveloped a heterogeneous hyperechoic solid mass of approximately 7 × 7 mm in size, without a blood flow signal. Regular ultrasound monitoring was continued during the pregnancy and neonatal periods. The infant underwent left testicular tumor resection at 10 months and 11 days after birth. The postoperative pathological result revealed a mature teratoma; after the treatment, the child presented no recurrences at the six-month follow-up visit.

Conclusions: Testicular teratomas should be suspected in fetuses with abdominal mixed cyst-solid or solid masses (especially in the presence of solid component calcifications) and an empty scrotum.

Introduction

Testicular tumors are infrequent in children and their incidence is only 0.5–2.0/100,000⁽¹⁾. Researchers in an American Academy of Pediatrics Prepubertal Testicular Tumor Registry study found a report of only 1 teratoma among 22 neonatal testicular tumors over 12 years and declared neonatal testicular teratomas to be extremely uncommon⁽²⁾. However, others have found that teratomas are the most common type of neonatal testicular tumor⁽³⁾. The neonatal period is relatively short and diagnoses may be missed during the period. In here, we report the case of an infant with testicular teratoma whose diagnosis and operation were delayed until 10 months after birth, although he had shown prenatal and neonatal clinical signs of the disease. We reviewed the literature on infancy testicular teratomas and summarized the published and our ultrasound prenatal findings to increase awareness of the condition and promote prompt diagnoses and treatments.

Case Presentation

A 29-year-old pregnant woman presented for a routine obstetric examination at 30 w + 2d of gestation, the ultrasound images showed a cystic mass (30 × 26 × 26 mm) in the left lower abdomen of the fetus. The inner wall surrounded a solid heterogeneous and hyperechoic mass of approximately 7 × 7 mm in size, lacking clear blood flow signals (Fig. 1). Subsequently, the pregnant woman underwent two more ultrasound examinations at 34w + 5d and 37w + 2d, which revealed tumor size increments, first to 28 × 26 × 22 mm and then to 32 × 28 × 22 mm, respectively. The size of the internal hyperechoic mass and its location remained unchanged. The fetus was diagnosed as having an abdominal cystic mass. At 37w + 6d of gestation, the mother gave birth to a baby boy weighing 3400 g with an Apgar score of 10. The newborn was in good general condition. Physical examination revealed an undescended left testis that was not palpated in the left groin area. Ultrasonography performed on the newborn 1 day after birth confirmed the presence of the right testis in the scrotum, and an empty left scrotum with an absent left testis that was undetectable in the groin area. A cystic mass (36 × 27 × 18 mm) was detected near the iliac fossa in the left lower abdomen. The inner wall contained a solid heterogeneous highly echogenic mass of 7 × 5 × 5 mm in size. We considered a diagnosis of left-sided cryptorchidism because the testicular dysplasia was accompanied by surrounding hydrocele, and we discharged the patient with an order for observation. On the 49th day after birth, the infant underwent another ultrasound examination. The size of the right testis was 15 × 8 mm, and the left cryptorchidism had been replaced with a descended testis into the scrotum, its size was 14 × 8 mm. However, the echo of the left testis was slightly high and uneven, and the bilateral testes were surrounded by anechoic components (Fig. 2). We diagnosed the infant as having left testicular dysplasia and bilateral hydrocele. At 10 months of age, the infant underwent an ultrasound examination that revealed an oval mass (30×16 mm) in the left scrotum with isoechoic and band-like hyperechoic areas, and anechoic areas still visible around it (Fig. 3). We considered a diagnosis of testicular teratoma on the basis of the ultrasound findings and ordered CT and MR examinations (Fig. 4). A plain CT scan showed a mass with a complete capsule and uniform density with small septa in the testis area. CT enhancement showed mild delayed enhancement of the capsule and septum, but no obvious enhancement was found in the mass. The MR imaging showed a uniform signal, high signals on T1WI and T2WI, decreased signal on the lipid-suppressing sequence, and no obvious enhancement, all the sequences were considered to contain fat components, and we diagnosed the infant as probably having a mature teratoma. At 10 months and 11 days after birth, the infant underwent left testicular tumor resection, and the postoperative pathological result confirmed the diagnosis of mature teratoma (Fig. 5).At the six-month postoperative follow-up, the child was recovering well.

Discussion

Testicular teratoma is a tumor originating from germ cells. The disease can be found during routine pregnancy examinations at the earliest, but accurately diagnosing it during the fetal period is difficult⁽⁴⁾. In this case report, a cystic mass in the lower left abdomen of the fetus was found during a routine obstetric examination and was identified twice during the pregnancy. The size of the cyst increased slightly, but the size of the internal hyperechoic light mass remained unchanged. A diagnosis of the origin or nature of the mass was not made during pregnancy. Cystic masses in the pelvis during the neonatal period are considered to be of testicular origin, but they are usually underdiagnosed because they lack typical teratoma features. That was the case in this patient who remained undiagnosed during the neonatal period. On the 49th day after birth, the testis descended into the scrotum, and the pelvic cystic mass disappeared, confirming our previous speculation about the origin of the mass; in addition, the previous hyperechoic mass increased with enhanced echo. The sizes of the bilateral testes were similar at that time, and we could not reach the correct diagnosis either. Once the child was ten months old, the left testis had undergone significant changes, and we were able to confirm the testicular teratoma diagnosis.

We found 8 case reports of prenatally diagnosed fetal teratoma in the PubMed database^(5–12), and we collected all the findings, including ours, to provide a general clinical picture summarizing the 9 cases. Most prenatal teratomas were identified during the third gestational trimester (7/9); the masses were all located in the pelvic and abdominal cavities (9/9), on left (6/9) and right (3/9) sides. We reviewed the ultrasound images of the published literature to summarize the findings. Ultrasound manifestations are divided into three types: (1) a cystic mass with a small solid mass inside (4/9); (2) a semi-cystic semi-solid mass with calcification in the solid part (2/9); (3) a solid mass with heterogeneous echo and calcification (3/9). Postnatal clinical examinations revealed single cryptorchidism (8/9) and bilateral cryptorchidism (1/9) (Table 1). We also found 3 reports of testicular teratoma during infancy published in the PubMed database (Table 2)^(13–15). All those cases presented abdominal (2/3) and testicular (1/9) masses, with 1/3 of them involving both testes. These 3 testicular teratomas were observed by ultrasound as cystic masses with hyperechoic and calcified portions.

Ultrasound findings of antenatal testicular teratomas are easily confused with ultrasound findings of other scrotal masses and need to be differentiated from hydrocele effusion, testicular torsion, and inguinal hernia. Hydrocele is the most common diagnosis of fetal scrotal masses, and cystic teratoma diagnoses require a high level of suspicion. Hydrocele presents with fluid-filled anechoic zones around the testis. The results of ultrasound imaging show an enlargement of the testicles and epididymis, and blood accumulating between the visceral and parietal layers of the vaginal membrane and outside the vaginal membrane, creating a picture of "bicyclic bleeding". In addition, testicular torsion should be suspected when color Doppler examination cannot detect blood flow signals within the testicular parenchyma. The main features of an inguinal hernia on ultrasound are the presence of peristaltic waves and small bowel loops in the scrotum, and color Doppler images of scrotal masses with visible blood flow⁽¹⁶⁾.

Teratomas can be divided into mature and immature tumors. The 12 cases of testicular teratomas summarized in this article were all mature teratomas. Prepubertal teratomas arise from early developmental stages in which germ cells fail to complete meiosis I, and they show no cytogenetic or molecular genetic abnormalities. Therefore, infantile testicular teratomas are usually benign. In contrast, post-pubertal testicular teratomas develop from germ cells in gonads that have failed to complete meiosis II, they can present as malignancies and can display complex cytogenetic aberrations such as heterochromatic 12p, which is characteristic of malignant germ cell tumors^(17–19). Moreover, animal experiments have shown that altered expression of cyclin D1 in male germ cells disrupts meiotic transitions and promotes testicular teratoma development⁽²⁰⁾. Of the 9 cases with prenatal signs in this paper, 4 were tested for AFP after birth (4/9). Among them, 3 cases presented values within the normal range (3/4), and 1 case had an elevated level (1/4). In addition, AFP levels were measured in 3 cases during infancy (3/3), 2 presented values within the normal range (2/3), and 1 had an elevated AFP level (1/3). Serum tumor markers help diagnose testicular tumors. However, the known normal adult serum AFP range cannot be used because serum AFP levels are higher in infancy. Then again, detecting elevated serum hCG values in the prepubertal disease age group is impractical because high serum hCG levels may lead to false-positive results⁽²¹⁾.

Treatments for childhood testicular tumors have changed considerably over the past decade. A growing number of pediatric oncologists believe that curative surgery is unnecessary⁽²²⁾. However, the 12 cases of testicular teratoma in this paper were all treated surgically. Only one patient with bilateral testicular teratoma in infancy underwent testicular preservation surgery of the testis with the smaller mass. The 12 cases in this paper were managed with surgical resection due to the early onset of the disease and the absence of normal testicular tissue in the tumors. Although most testicular teratomas are benign, some immature cases exist and ruling out malignancies is important. The precise diagnosis allows physicians to determine the treatment approach with either testicular preservation surgery or radical orchiectomy. Relevant studies have shown that the presence of normal testicular tissue on ultrasound, normal preoperative serum AFP levels or AFP < 100 ng/mL in 6- to 12-month-old patients, clear borders between the tumor and normal tissues, and tumor diameters < 3 cm are indications for tumor removal preserving the testis. If the preoperative ultrasonography does not confirm that the teratoma is benign, an intraoperative pathological examination is recommended before tumor removal for testis preservation⁽²²⁾.

We report a complete ultrasound monitoring progression of the lesion from the antenatal to the neonatal period and throughout the infancy of our patient, and we reviewed and summarized the published antenatal ultrasound reports of testicular teratomas, classifying the ultrasound images in a way that has not been done before. Moreover, we also summarized the ultrasound image characteristics of testicular teratomas in infancy. We hope our report will assist physicians during the early diagnosis of testicular teratomas.

Conclusion

Testicular teratomas should be suspected in patients with fetal intra-abdominal cysts mixed with solid masses, especially if there are calcifications in the solid component, and if the testis is not found in the scrotum.

Declarations

Ethics approval and consent to participate

Not applicable.

Consent for publication

Consent was informed and written consent to publish this information was obtained from the patient.

Availability of data and materials

The datasets used and/or analysed during the current study available from the corresponding author on reasonable request.

Competing interests

The authors report no conflict of interest about this paper.

Funding

Dalian Key Medical Specialties "Summit Plan" Project (# 2022ZZ230)

Author contributions

Data collection and analysis: YL and YS. Manuscript writing: YL and YS. Final approval of manuscript: YL and QY. All authors contributed to the article and approved the submitted version.

Acknowledgement

We would like to thank all the authors for their hard work.

Author details

1Department of Ultrasound, Dalian Municipal Central Hospital affiliated of Dalian Medical University, Dalian, China.

2Department of Ultrasound, Dalian Women and Children's Medical Group, Dalian, China. 

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