Introduction

Ovarian germ cell tumours (GCT) comprise of most common dysgerminomas, Yolk sac tumours, mixed germ cell tumors, embryonal carcinoma and teratomas respectively [1]. Dysgerminomas usually occur in the second to third decade of life and are usually unilateral, although bilateral cases are seen in around 15% [2]. It comprises 2% of all ovarian tumours [1, 2]. However, it is extremely rare to have dysgerminoma associated with pregnancy with an incidence of approximately 0.2–1 per 100,000 pregnancies [3]. These tumours can be of variable size ranging from a few centimetres to huge size nearly filling the abdomen. Timely and accurate diagnosis is important because it is mainly found in females of reproductive age and responds well to treatment, avoiding complications like infertility and mortality at a younger age [1]. There are various factors which can act as prognosticators such as early suspicion of a tumour, radiological findings, surgery, histopathological examination, and oncology team. This case is reported not just for its rare histopathological finding but the diagnostic dilemma it causes both to the surgeon as well as the pathologist.

Case presentation

A 27-year-old pregnant female presented with chief complaints of left-sided abdominal pain with a lump abdomen which was increasing in size for 2 months. It was associated with nausea, vomiting and amenorrhea for 2 months. She also had a history of irregular menstrual bleeding but no other symptoms of bladder/bowel compression were seen.

On clinical examination, vitals were stable. Abdominal examination revealed a firm, irregular, non-tender, mobile mass in the left adnexa, approximately 28 weeks in size of the pregnant uterus. It was non-adherent to the skin. Therefore, radiological examination was advised which on ultrasonography of the abdomen showed a large hypoechoic mass in the pelvis measuring 17 × 15 × 10 cm arising from the left adnexa and reaching up to the epigastrium. Also seen was an ectopic pregnancy in the right fallopian tube. There was 50 ml of ascitic fluid found. Further, a computed tomography (CT) scan revealed a hyperechoic irregular mass arising from the left adnexa measuring 18.5 × 14.3 × 9 cm suggestive of a neoplastic germ cell tumour.

The patient was investigated for routine investigations and was within limits. Alkaline phosphatase (ALP) 325 IU/l, beta-HCG 435 mIU/ml, alpha-fetoprotein 65 ng/ml, a n d CA-125 49 U/ml. Raised serum B- HCG was suspected to be due to concurrent pregnancy.

The patient was taken up for exploratory laparotomy with left salpingo-oophorectomy and right salpingectomy and the specimen was sent for histopathological examination. The gross examination of the specimen received showed a left ovarian tumour measuring 19 × 14 × 8 cm. The outer surface was encapsulated, greyish tan, bosselated with congested areas. The cut section showed cystic, solid and hemorrhagic areas (Fig. 1a,b). Multiple sections were given from representative areas for microscopic examination. H&E stained sections from the tumour showed nests of round to polyhedral cells divided by fibrous septa infiltrated by lymphocytes (Fig. 1c). These tumour cells had clear cytoplasm, vesicular chromatin and prominent nucleoli along with diffusely scattered multinucleated giant cells, reminiscent of syncytiotrophoblasts. There was no component of any other germ cell tumour like yolk sac/teratoma/embryonal carcinoma or choriocarcinoma histologically observed in the multiple sections. There was no extracapsular invasion of the tumour. The fallopian tubes, omentum, lymph nodes and peritoneal washings were free of tumours. Therefore, a diagnosis of dysgerminoma with syncytiotrophoblastic giant cells was suggested and further immunohistochemical markers were advised for confirmation. The tumour cells showed positivity for PLAP, CD117 (Fig. 1d), and SALL4 and were negative for cytokeratin, CD30, B-HCG and AFP. Thus a final diagnosis of dysgerminoma, left ovary was rendered. The patient was advised neoadjuvant chemotherapy and was followed up with a reduction in serial B-HCG and is recovering well.

Fig. 1
figure 1

a,b Gross examination shows an encapsulated grey tan tumour with bosselated outer surface (a). The Cut section showed a firm tan-coloured fleshy appearance with areas of haemorrhage and cystic change.a-intact ovary.b,c-cut section of tumour (b). c H E stained section shows tumour cells arranged in the nest and separated by fibrous septa along with many Syncytiotrophoblastic giant cells in the background of tumour cells (arrow). (H&E stain,40X). d The section examined shows tumour cells positive for Immunohistochemistry CD-117 (IHC CD117,40 X)

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Discussion

Dysgerminoma is a rare malignant ovarian tumour comprising less than 5% of all ovarian malignancies [2]. These lesions are most commonly found in adolescents and young females with approximately 2/3rd of cases in less than 20 years of age [3]. It is rare to have concurrent pregnancy with dysgerminoma [4]. Zhang et al. report a viable pregnancy with ovarian dysgerminoma in a 25-year-old pregnant woman [4]. Chen et al. reported a case of a 23-year-old pregnant female with dysgerminoma of the right ovary with simultaneous abdominal desmoid tumour [3]. Reda et al. diagnosed a case of dysgerminoma of the right ovary with a viable intrauterine pregnancy at 10 weeks [5]. Natural conception is possible in females with dysgerminoma but it can be difficult in most cases with variable prognosis of mother, fetus and the tumour [5]. The pregnancies occurring in such cases can be ectopic and can lead to complications like rupture and ovarian torsion. It can also lead to diagnostic dilemmas for the clinician. The ideal treatment for the mother can be compromised due to the ongoing pregnancy.

It usually presents with nonspecific findings such as abdominal distention, mass or abdominal pain. Some patients have menstrual abnormalities or compression symptoms [6]. Radiological examination can give a clue to malignant aetiology. However, a CT scan of the abdomen and pelvis may pose an increased risk to the developing fetus, although not very significant [5].

MRI is a sensitive test with an accuracy of 98% for diagnosing ovarian tumours. However, it has been mistaken for fibroid, especially when cystic change is seen [7]. A high titre of B- HCG results sometimes may have clinical features similar to either ectopic pregnancy or hydatiform mole [8]. Serial B-HCG titre should be performed to follow such patients as around 3% of patients with a pure dysgerminoma ovary may have an increased amount of B-HCG in the blood, secreted by syncytiotrophoblastic cells within the tumour tissue [9].

Histopathology can help solve such diagnostic dilemmas. On gross examination, the tumour has a smooth capsule, although it may have a nodular appearance. On microscopy, the tumour cells are large round to polygonal with vesicular nuclei containing one or more nucleoli, clear to granular cytoplasm. Lymphocytic infiltrates are seen within the fibrous septae, which is a characteristic histological finding [9]. In around 5% of dysgerminomas, syncytiotrophoblastic giant cells, the source of increased levels of gonadotrophin are seen [9]. There are a few cases reported of dysgerminoma with syncytiotrophoblast giant cells which are summarized in Table 1. Rarely, dysgerminomas may have syncytiotrophoblastic giant cells infiltrating tumour cells which produce B-HCG. Therefore, it is empirical to have a pre-operative evaluation of these markers in cases of suspected ovarian dysgerminomas.

Table 1 Reported cases of dysgerminoma with syncytiotrophoblastic giant cells
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Immunohistochemical stains are needed to confirm the diagnosis of pure dysgerminoma with the exclusion of other associated mixed germ cell tumour components. The tumour cells are positive for PLAP, CD117, SALL4, D2-40, OCT- 4, and NANOG and negative for CD30, CK, B-HCG, EMA, ER and PR [9].

Although this is a highly malignant tumour but it responds well to treatment. These tumours are radiosensitive with a good prognosis if treated timely. Factors like the large size of the tumour and the advanced stage at presentation of the tumour are bad prognostic indicators [5]. Unilateral oophorectomy and surgical staging are the minimal surgeries prescribed in cases of ovarian germ cell tumours and dysgerminomas as fertility preservation in younger age group females is the main issue [6].

Conclusion

Dysgerminoma ovary is an aggressive neoplasm occurring in young females. It is extremely rare to have concurrent pregnancy associated with dysgerminoma and it leads to additional complications like torsion ovary. Thus, a timely intervention and fertility-sparing surgery are required in such cases. It has a characteristic histopathological finding but sometimes may have syncytiotrophoblastic giant cells along with tumour cells.