Bakre Tejashree *, Patil Lalita Y**,
(* Second Year Resident, *** Professor. Department of Obstetrics and Gynecology, ** Assistant Professor, Department of Pathology;
College and K.E.M
Hospital, .) Mumbai, India
A 20 year old primigravida with 19 weeks of pregnancy came with pain in abdomen, dysuria and frequent urination. She was diagnosed as a case of Gastro Intestinal Stromal Tumor (GIST) of the descending colon on ultrasonography (USG). Magnetic resonance imaging (MRI) & Doppler sonography diagnosed the mass as a sub-serosal fibroid of the uterus. During emergency lower segment cesarean section (LSCS) at term the ovarian origin of the mass was discovered.
Dysgerminoma is the commonest malignant ovarian germ cell tumor diagnosed in pregnancy.[1,2,3] These tumors can however be misdiagnosed as sub-serosal fibroids or tumors of the colon. At times modalities like Doppler and MRI can also lead to misdiagnoses. Such masses are then diagnosed accidentally. Here we present a case of left ovarian dysgerminoma misdiagnosed as fibroid during antenatal period resulting in delay of her definitive treatment.
A 20 year old primigravida with 19 weeks of gestation presented with complaints of dull aching pain in left lumbar region and dysuria for 15 days. On examination her vital parameters were stable, chest was clear, abdominally uterus was 20 weeks in size and relaxed. An 11 x 8 cm sized non tender mass separate from uterus and hard in consistency was palpated in left lumbar region. On vaginal examination a firm, non tender mass was felt high up in the left fornix. An ultrasound examination revealed a 19 weeks size normal intrauterine fetus and a large hyperechoic, well defined, highly vascular mass measuring 11cm x 8 cm x 8 cm in the left lumbar region. USG differential diagnosis was GIST of the descending colon or a left subserosal fibroid of the uterus. MRI of the pelvis and abdomen was suggestive of a large subserosal or broad ligament fibroid but possibility of GIST could not be ruled out. The patient was closely followed by obstetrician and gastroenterologist. Rest of antenatal period was unremarkable. The patient underwent an emergency LSCS under spinal anesthesia at term in view of thick meconium stained liquor in latent stage of labor. Intraoperatively, after birth of a term fetus a large lobulated mass, hard in consistency, smooth surfaced, measuring 25 x 20 x 8 cm arising from the left ovary and free from the bowel was seen. A thick leash of blood vessels was seen extending from the base of the mass to the left cornua of the uterus and into the mesosalpinx.
Figure 1. Large left ovarian tumor with a thick leash of vessels during Cesarean section.
M: is the mass. Arrow shows the thick leash of blood vessels in the mesoovarium.
The surgeon deferred the excision of the mass due to its high vascularity and the thick leash of blood vessels seen in its pedicle. Tumor markers like LDH, AFP and β-HCG were sent, chest radiograph was obtained. Tumor markers (LDH-2290 U/L and β -HCG – 26 mIU/L) were elevated. Exploratory laparotomy was performed after puerperium. Peritoneal washings were sent for cytology. A left ovarian mass lobulated, bosselated 19 x15 x5 cm in size was seen. A left salpingo-oophorectomy was done and the tumor was sent for frozen section.Cut surface was solid, greyish white, firm, fleshy, and bulging. Frozen section was suggestive of a malignant ovarian tumor probably a mixed germ cell tumor.
Figure 2a. Left large ovarian neoplasm. M is the mass; Black arrow is the vascular pedicle and the green arrow shows the normal uterus.
Figure 2b. Gross: Large, lobulated 19 x15 x5 cm, solid mass.
Figure 3. Cut surface: Solid, greyish-white, fleshy with bulging cut surface.
Opposite ovary and uterus were inspected which were grossly normal. Peritoneum of the cul de sac, liver, omentum, under surface of the diaphragm, colon, bowel mesentery, spleen, bladder peritoneum, pelvic and para aortic lymph nodes were evaluated and found to be grossly normal. As the patient was young and desirous of further child bearing only unilateral salpingo-oophorectomy was done. Peritoneal cytology showed presence of malignant cells (FIGO stage 1c). Final histopathology report confirmed the tumor to be an ovarian dysgerminoma. The patient was referred to an oncology center for adjuvant treatment.
Figure 4. H&E 40X: Shows tumor cells are arranged in nests, sheets and cord separated by fibrous septae. C are the tumor cells and S are the fibrous septae.
Figure 5. H&E 100X: Shows stromal lymphocytic infiltration (L) and few mitotic figures were seen.
Figure 6. H&E 400X: Shows large round to polygonal cells with high N:C ratio, pleomorphic hyperchromatic nuclei, thick nuclear membrane, prominent eosinophilic nucleoli and moderate vacuolated cytoplasm.
Dysgerminoma accounts for only 1-2% of all malignant ovarian tumors. Dysgerminoma occurs mainly in children and young women. The average age is 22 years, and 90 percent of the patients are less than 30 years of age. About 20 percent of malignant ovarian tumors detected during pregnancy are dysgerminomas. Differential diagnosis of a pelvic mass in pregnancy include uterine leiomyomas, overdistended urinary bladder, ovarian neoplastic cysts, GIST, impacted feces, large hydrosalpinx and retroperitoneal tumor. 
This case is interesting as it posed diagnostic challenges ranging from GIST to subserosal leiomyoma and finally dysgerminoma. USG is the primary imaging modality. However not only USG but also MRI misdiagnosed the dysgerminoma as a fibroid uterus in our case. MRI has around 98% sensitivity for detecting ovarian origin of a mass.[4,7] However there have been reports of mistaking a malignant ovarian tumor for pedunculated uterine fibroid with areas of cystic degeneration as in our case. Such adnexal masses are then diagnosed for first time during LSCS. Tumor markers elevated in a case of a dysgerminoma are most commonly LDH and occasionally β-HCG, when the dysgerminoma has components of syncytiotrophoblasts. Raised AFP is less common. Preoperative evaluation of all of the tumor markers is advisable in patients with suspected germ cell tumor or dysgerminoma. A MRI diagnosis of fibroid uterus misguided us and so tumor markers were not studied in the antenatal period. Had these tumor markers been done the diagnosis would have been established and the patient could have been operated in the antenatal period itself, or along with LSCS. The tumor may then have been staged as FIGO stage 1a. For patients with stage Ia dysgerminoma, unilateral salpingo-oophorectomy conserving the uterus and opposite ovary is accepted treatment in a young patient desirous of preserving her fertility. The initial treatment of these patients is surgery, which includes unilateral salpingo-oophorectomy. Frozen section is performed. Multiple biopsies from the peritoneum, omentum, and contralateral ovary, and pre- and paraaortic lymph nodes are taken and studied. Peritoneal washings are subjected for cytological analysis. The frozen section pathologic diagnosis in our case was mixed germ cell tumor as the pathologist studied only representative section. In such cases it is best to defer definitive surgery. Fortunately, the accuracy of frozen section diagnosis of ovarian tumors is more than 90%. Incompletely staged patients or those with higher stage tumors (1c and above) should probably receive adjuvant treatment like radiation therapy or chemotherapy. 
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Bakre T, Patil LY,
Dysgerminoma Masquerading As a Subserosal Fibroid in Pregnancy. JPGO
2014 Volume 1 Number 5 Available from: http://www.jpgo.org/2014/05/huge-ovarian-dysgerminoma-masquerading.html Gupta