58 year old male patient started feeling weakness in both his legs 7 months ago, could stand but felt weak in both legs. he also had a mild but tolerable dyspnea, able to lie fully flat. several months later weakness got worse and would frequently fall. 1 month ago felt pain on the left side of his back and also experienced diaphoresis. urination and defecation remained normal. on examination. there was a 1x2 cm hard nodule on the right supraclavicular area. right lung had lag in expansion, decreased breath sounds, and dullness on percussion. both legs had a strength grading of 3/5 upper extremities normal. legs had decresed sensation and reflexes. cerebellar and cranial nerve functions intact. on the 2nd hospital day 1-2 liters of bloody pleural fluid was extracted from the right lung during a thoracentesis. what could this be?