HI doc, my best friend s mother 72yo wf w/ h/o melanoma in R eye in the early stage and tx surgically, 2 y ago, relatively w/ good outcome (no enuclation and not bad preserved vision until now) around 2-3 weeks ago c/o sob, tireness esp w/ physical activities. Yesterday was dx w/ pleural effusion and thoracentesis was done (around 2L of urine lookin fluid)She was under good health care ; no HTN DM no obesity no CAD or heart problem lately, no meds expect benzodiazepams for last 8 years, no cough or sputum no UTI orURI although c/o vague LLQ abd pain 3 weeks ago .What would be the most probable cause ? she does not have any test results yet. thanku kindly and sorry if the quuestion is to stupid . chris