Pseudochylothorax: An unusual mode of revelation of pleural metastasis from solid tumor

Pseudochylothorax is a rare cause of pleural effusion. Sometimes confounded with chylothorax, firm diagnosis relies on analysis of the pleural liquid: exudative liquid (protein >30 g/L, lactate dehydrogenase >200 UI/L) with a high level of cholesterol (usually >200 mg/dL), low level of triglyceride (usually <110 mg/dL), cholesterol total/triglyceride ratio >1, absence of chylomicron, and in some cases the presence of cholesterol crystals. Pseudochylothorax is secondary to tuberculosis and rheumatoid arthritis in nearly 90% of cases. Its oncologic etiologies are mainly represented by malignant hematologic disorders.

We report the first case of pseudochylothorax whose cause was the pleural metastasis of an extrathoracic solid tumor in a 61-year-old man with a medical history of oropharynx carcinoma.

Computed tomography scan disclosed a left partitioned effusion of high abundance, responsible for a passive atelectasis of the left lower lobe and multiple bilateral pulmonary nodules. A drainage tube was inserted to allow the evacuation of serous liquid; biochemical examination revealed an exudative effusion with pseudochylothorax criteria. Because the daily chest drainage output remained greater than 1 L per day, videothoracoscopy pleural biopsies and talc pleurodesis were performed. Histopathologic examination of the pleural biopsies found a pleural localization of oropharynx carcinoma.

Because its occurrence is probably underestimated, when pseudochylothorax is diagnosed, oncologic causes should be considered.