A 41-year-old woman was admitted to the hospital with a clinical history of recurrent lower abdominal pain.
She had a past medical history of epilepsy since the age of 17, currently under treatment, obesity WHO grade I and arterial hypertension. Ten years ago, she underwent a removal of an ovarian cyst, whereby the side remained unclear. Her sister was suffering from systemic sclerosis and her uncle was diagnosed with lung cancer. In a previous gynecological sonography report a cystic lesion measuring 44 x 27 x 30 mm was described which could be differentiated from the adnexal ligament and was located cranially to the uterus.
At the time of admission, the patient was asymptomatic, and both her physical examination and vital signs were unremarkable. The abdomen presented soft, and not distended with normoactive bowel sounds. There were no signs of hepatosplenomegaly or any masses.
Because of the patient’s young age magnetic resonance imaging (MRI) was performed and showed a multicystic solid retroperitoneal mass ventral to the psoas muscle and the left iliac artery with a polycystic portion of 37 x 26 x 45 mm ventrally (Fig. 1a), and a lobulated, partly cystic and partly solid portion of 36 x 15 x 33 mm dorsally (Fig. 1b) with vascular contact, ultimately of unclear etiology. Due to the solid part of the tumor, a malignant aspect was considered with the fatty part being indicative of a retroperitoneal teratoma. Differentially, cystic mesothelioma, mucinous cystadenoma, and lymphatic malformation were also considered but deemed unlikely due to the solid parts of the mass. No connection to the ovary or parenchymal bridge of the presumed horseshoe kidney was detected.
After an interdisciplinary discussion of the radiological findings, surgical removal of the retroperitoneal mass was recommended.
A diagnostic laparoscopy was performed. After locating and sparing the iliac vessels and the left ureter, mobilisation of the sigmoid colon and left flexure was performed. In view of the adhesions between the tumour mass and the iliac vessels a conversion to laparotomy was necessary. The tumor mass was then completely removed. The patient's postoperative course was uneventful and she was discharged after three days.
Histological workup revealed fragmentary retroperitoneal teratoma with evidence of a papillary thyroid carcinoma of 1.4 cm in one of the fragments (Figs. 2a and 2b) and consistent nuclear expressions of PAX8 and TTF-1. There was no evidence of lymphangiosis or hemangiosis carcinomatosa and no perineural sheath infiltrations. Resection in toto (minimal distance to the surface of the affected fragment 0.01 cm) was confirmed.
Considering the histological results, a further staging has been completed. A thyroid sonography showed neither a pathological finding in the gland nor cervical lymphadenopathy. Enhanced chest computed tomography (CT) of the neck, thorax and abdomen was performed and showed no evidence of cervicothoracic or abdominal tumor manifestations.
Tumor markers for a malignant germ cell tumor and thyroid function parameters were all within the normal range.
As this retroperitoneal teratoma behaved like a malignant struma ovarii (MSO), it was re-discussed in both, the endocrinological and gynecological department whether an adnexectomy should be recommended on the left side. Gynecological examination and vaginal sonography revealed no suspicious finding, while both ovaries presented unremarkable with normal follicular structure in the ultrasound. There was no evidence of other space-occupying lesions in the lesser pelvis and no free fluid in the Douglas space.
From a gynecological point of view, there was no indication of unilateral adnexectomy because the retroperitoneal teratoma was removed from a different compartment and distant from the inconspicuous left ovary.
Because there is no evidence-based opinion about the benefit of such an operation, it was intensively discussed with the patient and agreed to refrain from surgical removal of the adnexa and to continue with regular monitoring of the ovaries. Regarding the thyroid carcinoma in the teratoma with increased risk due to the size, total thyroidectomy and subsequently a radioiodine therapy were recommended in analogy to the same carcinoma of the thyroid gland, whereby a lifelong hormone substitution would be necessary afterwards.
Therefore, a complete thyroid gland removal was discussed and scheduled upon consent.
The neck exploration intraoperatively showed macroscopically an inconspicuous thyroid gland on both sides. Both thyroid lobes were removed in toto. The patient tolerated the procedure well and was able to leave the hospital after a hospitalization of two days.
Histology revealed diffuse normo-follicular colloid struma without evidence of dysplastic or malignant changes. Radioiodine ablation will be performed five weeks after thyroidectomy.