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5. Lymphangioleiomyomatosis
Lymphangioleiomyomatosis (LAM) is an uncommon disease, female-predominant, that is a type of cystic lung disease that has characteristic diffuse thin-walled cysts (1). This disease is caused by the neoplastic growth of smooth muscle cells and spreads via the lymph and hematogenously. Pathology exhibits characteristic infiltration of HMB-45 LAM cells with a smooth muscle phenotype. Inheritance can be autosomal dominant (tuberous sclerosis-LAM) or sporadic (S-LAM), with some males being affected, solely with the TSC-LAM type. Pneumothoraces are common with average age of the first pneumothorax around 35 years of age and a recurrence rate of approximately 75%.
The patient did have small right-sided pleural effusion. Given her known diagnosis now of LAM, what would be the most likely finding on pleural fluid analysis? (Click on correct answer to proceed to the fourth of five panels)