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.
Table 1
Summary of eight published prenatally diagnosed fetal teratoma case reports
Author/Year | Maternal age (years) | gestational week | Tumor size (cm) | Ultrasound appearance | tumor location | initial diagnosis | Clinical manifestations after birth | AFP(mg/ml) | Surgical approach | pathological result | Postoperative outcome |
Mboyo,1997 | - | 31 | 2.5×2.3 | Mainly cystic mass with smaller solid mass | Left side of bladder | Retroperitoneal teratoma or neuroblastoma | Left abdominal mass and left scrotal emptiness | 7980 | left orchiectomy | Mature teratoma | Persistent left vesicorenal reflux 1 year after operation |
Shih, 1997 | 33 | 36 | 5×4×3 | Semi-cystic semi-solid mass; calcification and acoustic shadows in the solid part; blood flow signals detected | Right kidney and anterior to bladder | Peritoneal tumor | Right upper quadrant mass; undescended right testis | within the normal range | right tumor resection | Mature teratoma | Normal AFP at 1-year follow-up |
Siu, 2001 | 40 | 30 | 3 | Semi-cystic semi-solid mass; calcifications seen in solid portion | Below the liver, in front of the right kidney, above the bladder | Teratoma | Bilateral cryptorchidism | within the normal range | Laparoscopic tumor resection | Mature teratoma | Positive |
Pramanik, 2011 | - | 27 | 2.1×1.9 | Solid predominant mass with minimal calcifications | Right iliac fossa | Teratoma | Right cryptorchidism | within the normal range | laparotomy tumor resection | Mature teratoma | - |
Janda, 2014 | - | 22 | 1.0×1.2 | Mainly cystic mass with smaller solid mass | Adjacent to the bladder | - | Missing left testis | - | laparotomy tumor resection | Mature teratoma | Positive |
Youssef, 2016 | 31 | 32 | 2.0×2.0×2.2 | Mainly cystic mass with smaller solid mass | Between left kidney and bladder | Cryptorchid testicular teratoma | Left cryptorchidism | - | Laparoscopic tumor resection | Mature teratoma | Good at 1 year old |
Arkar, 2016 | 26 | 36 | 2.0×1.8 | Solid predominant mass with coarse calcifications | Left side of bladder | Cryptorchid testicular teratoma | Left cryptorchidism | - | Laparotomy tumor resection | Mature teratoma | Good postoperative |
Le Quoy, 2020 | 33 | 30 | 2.9×2.5 | Solid predominant mass with coarse calcifications | Between left kidney and bladder | - | Left cryptorchidism; abdominal mobile mass | - | Laparotomy tumor resection | Mature teratoma | Good postoperative |
This case | 29 | 30 | 3×2.6×2.6 | Mainly cystic mass with smaller solid mass | Left side of bladder | Abdominal cystic mass | Left cryptorchidism, abdominal cystic mass | - | Left orchiectomy | Mature teratoma | Good half a year after surgery |
Table 2
Summary of three published infant testicular teratoma cases
Author/Year | age in months | clinical manifestations | Ultrasound appearance | tumor marker | AFP(ng/ml) | Tumor size (cm) | Surgical approach | pathological result | Postoperative outcome |
Brown, 1995 | 7 | The left scrotum is normal in size, the right scrotum is empty, and the right abdominal mass | Cystic lesions below the liver | - | within the normal range | 5.5 | laparotomy tumor resection | Cystic teratoma with patchy necrosis | The child is good after 18 months |
Herek, 2004 | 10 | left testicular mass | On the left is a cystic, solid, calcified mass; on the right, a smaller mass | - | 37.6 | 1.9x1.3(L) 0.6X0.3(R) | Left radical orchiectomy; right tumor resection with preservation of surrounding normal testicular tissue | mature teratoma | AFP returned to normal, no recurrence after three years, the preserved right testicular parenchyma had normal echo, and physical development was normal |
Tanaka,2009 | 2 | Left scrotal emptiness, solid mass in left abdomen | Double hydronephrosis, a large cystic tumor with focal calcification in the lower abdomen | within the normal range | 297 | 12.5x10.5x5.5 | - | teratoma | Left hydronephrosis, atrophy, no tumor recurrence, normal serum alpha-fetoprotein level |
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.