To the Editor:Dyspnea is the term generally applied to the unpleasant or uncomfortable sensation often described by patients as ''breathlessness.'' The American Thoracic Society defines dyspnea as ''a subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity. The experience is derived from interaction among physiological, psychological, social, and environmental factors and may induce secondary physiological and behavioral responses.'' 1 The reported frequency in cancer patients varies from 21% to 90% depending on the stage of the cancer. 2,3 Although this case illustrates a rarer cause of dyspnea, it emphasizes the importance of identifying possible reversible causes before treatment is implemented.