A rare case of high-grade serous ovarian epithelial carcinoma presenting as an isolated cystic mediastinal mass: a case report and brief review of the literature

Abstract

A 70-year-old woman presented with a 2-year history of increasing breathlessness. Computed tomography (CT) of the chest confirmed a well-defined cystic lesion abutting the mediastinum in the right hemi thorax measuring 8 × 6 cm. She underwent a right thoracotomy to excise the cystic lesion. Biopsies for histology demonstrated metastatic serous ovarian epithelial carcinoma. We report a very unusual primary presentation of ovarian epithelial carcinoma as a single cystic mediastinal mass. We also include a brief review of the literature.

Case history

A 70-year-old woman presented with a 2-year history dyspnoea. Originally diagnosed as asthma, it failed to respond to inhaled bronchodilators and steroids. She could manage climbing one flight of stairs (NYHA III). She had a persistent dry cough but no chest pain. She was a life-long non-smoker. Previous medical history included thyrotoxicosis treated with radioactive iodine, now on thyroid replacement, hypertension (medically controlled), hypercholesterolaemia and rheumatic fever as a child.

There had been progressive deterioration in her spirometry: forced expiratory volume in 1 s (FEV1) 0.8 l (50% predicted); forced vital capacity (FVC) 1.2 l. A chest X-ray was noted to be abnormal; computed tomography (CT) of the chest (Fig. 1) confirmed a well-defined cystic lesion abutting the mediastinum in the right hemithorax measuring 8 × 6 cm. Although predominantly fluid-filled, there were some nodular areas of soft tissue in its inferior aspect. Superiorly, it extended to the right hilum and inferiorly to the medial aspect of the right hemidiaphragm indenting the right side of the pericardium and compressing the right lower lobe bronchus. Echocardiogram demonstrated a pericardiac mass with no alteration of cardiac function. Ejection fraction was estimated at 55–60%. The valves were normal.

Figure 1.

CT scan showing well-defined cystic lesion abutting the mediastinum in the right hemithorax measuring 8 ×6 cm.

The differential diagnosis at this stage included a pericardial or bronchogenic cyst. Due to the dyspnoea, she was scheduled for resection of the mediastinal mass. Prior to admission, she presented to her family doctor with a new abdominal mass. CT showed the presence of enlarged left para-aortic lymph nodes, prominent nodes in the common iliac and external iliac regions and a large adnexal cystic mass 19 × 11 cm with septations. Biopsy of para-aortic lymph nodes showed high-grade serous carcinoma.

Five weeks after the thoracic CT scan, she underwent a rigid bronchoscopy, right thoracotomy, pleural biopsy, de-roofing of the mediastinal cyst and pleurodesis. The aim was symptomatic relief and an improvement in her performance status to allow chemotherapy. At surgery, the cyst was indenting the mediastinal aspect of the right middle and lower lobes and seemed to be in contiguity with the pericardium. The resected specimen was sent for analysis. The cyst wall demonstrated papillary serous adenocarcinoma carcinoma of the female genital tract. The cells were positive for cytokeratin K-7 and showed strong, nuclear positivity for WT-1. They were negative for CA-125, TTF-1, thyroglobulin, CK-20 and ER. The patient’s CA-125 was 622 kU/l at this time.

Recovery was uneventful and breathlessness improved. The patient was subsequently referred to the gynaecology and oncology team for treatment. She had six cycles of neo-adjuvant chemotherapy with carboplatin/paclitaxel to down-stage the disease. This was followed by bilateral ureteric stenting and she subsequently underwent a laparotomy, total abdominal hysterectomy, bilateral salpingo-oophorectomy and omentectomy.

The final histology confirmed high-grade serous carcinoma of both ovaries with involvement of corpus and cervix. The omentum had no evidence of metastasis. The patient remains in recession from the disease and is well at 6-week follow-up after curative resection.

Discussion

Mediastinal cysts are relatively uncommon. They are classified into foregut-derived cysts, mesothelial cysts including pericardial and pleural cysts, thymic cysts, and other rare variants. Cysts of the posterior mediastinum showing Müllerian differentiation (Hattori’s cysts) have been described. These are rare and represent a benign entity being located usually in the posterior mediastinum.

Although ovarian carcinoma commonly metastasises to the pleura and lung parenchyma, mediastinal deposits are infrequent. We could only find four reports in the literature of mediastinal metastases from high-grade serous ovarian carcinoma.^1–4 This suggests that non-pulmonary metastases alone as the sole form of distant (extra-abdominal) metastatic spread are very unusual. Even the largest published series of presentations of ovarian carcinoma by the MD Anderson Cancer Center, does not include a single case of mediastinal involvement.⁵

As in this case, differentiation between papillary pattern, most commonly from thyroid, lung, pleura and breast can be made by clear nuclei and pseudo-inclusions that are not present in ovarian tumours. Immunostaining for TTF-1 and thyroglobulin may help the case. Papillary mesothelial tumours have a more monomorphic pattern with the immunoprofile positive for calretinin, cytokeratins 5/6 and vimentin. Lung and breast carcinoma may be distinguished as they are negative for WT1.

In our case, the cytokeratin 7 and WT1 staining together with high serum CA125 made the case for a müellerian-derived tumour. Strong nuclear positivity for WT1 confirms ovarian serous histotype.

Conclusions

The differential diagnosis of mediastinal mass must include neoplastic disease. Serous ovarian epithelial carcinoma usually presents with abdominal symptoms and early spread (locoregional and metastatic). Although metastasis to the lungs is a common feature of this type of tumour, the presentation with mediastinal disease must be borne in mind. As a consequence, the diagnostic immunopanel for such tumours must include WT1, CA125 and the above mentioned markers to delineate the possibility of a serous adenocarcinoma of ovarian origin, even if the clinical and investigative features of an abdominal mass are initially absent.