Chylothorax and Chylopericardium as Initial Presentation of Thymoma: A Case Report

Thymoma is a rare tumor of unknown malignancy with estimated prevalence of only 0.2% to 1.5% of all malignancies.⁽¹⁾ Although rare, it is the most common anterior mediastinal mass. Thymic tumours are a heterogeneous group of malignancies with a range of clinical presentation, often limited to the anterior mediastinum and without an aggressive disease profile. It is asymptomatic in majority of cases. Chylothorax from thymoma were not mentioned in literature. However, in a journal by Raya et al (2017), a 28-year-old Hispanic woman diagnosed with thymoma presented with chylothorax and chylopericardium. On work-up, it showed a rare transformation of classical Hodgkin’s lymphoma from previous thymoma. Based on the journal of thoracic oncology, association between thymoma and subsequent development of non-Hodgkins lymphoma is established to be due to the disruption of T-cell function caused by either the thymoma itself or it’s treatment. Several studies have documented associated malignancies however, small population were used in the study. It is not possible to draw an absolute conclusion, but there may be a small increased risk of subsequent malignancies in those individuals who develop a thymoma.^(2)(3)(4)

Chylothorax is a rare clinical condition characterized by pleural fluid with a turbid or milky appearance due to high triglyceride content in the form of chylomicrons that enters the pleural space. Malignancy is a leading cause of non-traumatic chylothorax responsible for 63% of non-traumatic causes. Lymphoma is the single most common cause responsible for 50% of the non-traumatic causes. Other common causes of chylothorax are Castleman's disease, sarcoidosis, histoplasmosis, lymphangioleiomyomatosis, Noonan syndrome, filariasis, heart failure, lymphangitis of the thoracic duct, aneurysm of the thoracic aorta that erodes the duct, Cirrhosis of the liver, childbirth and idiopathic.⁽⁵⁾ Surgical procedures and chest trauma are the most common causes of the traumatic chylothorax. Diagnosis of chylothorax is established by direct analysis of the pleural fluid obtained from thoracentesis. The fluid is characteristically milky in appearance. The triglyceride concentration greater than 110 mg/dl, a ratio of pleural fluid to serum triglyceride of greater than 1.0, and ratio of pleural fluid to serum cholesterol of less than 1.0 usually confirms chylothorax. Chylothorax will be excluded if pleural fluid triglyceride concentration is less than 50 mg/dl.⁽⁶⁾ This criteria was fulfilled in the case presented. The cornerstone of treatment are adequate fluid and electrolyte replacement along with appropriate nutrition. In cases of non-traumatic chylothorax, treatment of the underlying disease such as chemotherapy and irradiation can lead to improvement, but success rates are limited up to 33%.⁽⁷⁾

Chylous pericardial effusions are extremely rare but have been described in literature, originally noted to occur in 3% of patients with nontraumatic chylothoraces.⁽⁸⁾ Currently, the management of chylopericardium and more commonly chylothoraces is based on the etiology and consists of a strict dietary fat restriction, surgical intervention if indicated, and treating the underlying cause.⁽⁹⁾ The potential causes of chylous effusions are extremely broad but primarily fall into 4 categories: malignancies, trauma, idiopathic, and miscellaneous with lymphoma being the most common nontraumatic cause. ⁽¹⁰⁾