Ovarian hyperstimulation syndrome (OHSS) is an increasingly recognized complication associated with in vitro fertilization (IVF). Hyperplastic mesothelial cells in lymph nodes is a rare entity often simulating metastatic carcinomas. We report a case of chylothorax, mediastinal mass, and hyperplastic mesothelial cells associated with OHSS.
A 34 year old white female with history of infertility and polycystic ovarian syndrome (PCOS) presented with 2 week history of increasing dyspnea, orthopnea, and decline in activity. In December 2004 she underwent successful IVF with subsequent twin intrauterine pregnancy. Shortly afterwards, she was admitted for OHSS and massive ascites requiring paracentesis. She complained of dyspnea which resolved with treatment. She had returned to her usual state of health until 2 weeks prior to admission at our hospital when she noted pain, redness, and swelling of her left arm. She suspected a spider bite but did not seek medical care. Her complaints resolved however were followed by respiratory problems. Pertinent exam findings included tachycardia, tachypnea, and hypoxia. There were diminished breath sounds, dullness to percussion, and decreased tactile fremitus over the left hemithorax. Laboratory evaluation was notable for leukocytosis and anemia. A chest radiograph showed a large left pleural effusion. A thoracentesis was performed with drainage of milky white pleural fluid consistent with chylothorax. She was transferred to our facility where a left thoracostomy tube was placed. A contrasted CT of the chest showed bilateral upper extremity venous thrombi, left axillary adenopathy and fluid attenuated structures located in the prevascular mediastinum. These were suggestive of adenopathy, but were not located along the thoracic duct. A left thoracotomy with lymph node sampling was done. This showed large numbers of proliferating well differentiated mesothelial cells within the sinuses of the lymph nodes, a rare entity known as hyperplastic mesothelial cells.
Hyperplastic mesothelial cells in lymph nodes have been described mainly in case reports. They have been identified in mediastinal lymph nodes associated with pericardial and pleural effusions (1, 2). Their presence can simulate malignancy by demonstrating atypical cytological and architectural features(2). We postulate the hyperplastic cells resulted in the formation of her chylothorax, although we are unaware of any previously reported cases. OHSS could also be an etiology as well. The prevalence of moderate to severe OHSS ranges from 1-10% in major IVF programs (3). Risk factors include young age, low body mass index, history of PCOS, atopy, and the use of GnRH antagonists in IVF(4). Clinical features include ascites, pleural and pericardial effusions. Patients complain of nausea, vomiting, diarrhea, dyspnea, and abdominal discomfort. Lab abnormalities can include hyponatremia, hyperkalemia, hemoconcentration, leukocytosis and abnormal liver function tests. Respiratory distress can ensue and is due to ascites, pulmonary edema, and hemorrhage. OHSS is also associated with thromboembolic disease and sepsis. Treatment is supportive. The goal is to maintain intravascular volume and systemic perfusion. Paracentesis, thoracentesis and anticoagulation can be done in these patients.
As the number of patients undergoing assisted fertilization techniques increase, physicians should recognize the clinical manifestations of OHSS. Complications can lead to significant morbidity and mortality whereas the presence of hyperplastic mesothelial cells can also provide a diagnostic challenge in the diagnosis of underlying malignancy.
Shirley Jones, None.