Although Aspergillus frequently invades tissue, it is also well known for its propensity to form noninvasive, obstructing mycelial masses. These have been observed to occur in pulmonary cavitations as mycetomas1-4and in bronchiectasis as bronchial casts.3,4They may produce suffocation,5asthma or atelectasis,4or bronchiectasis.1Pulmonary emboli composed of Aspergillus mycelia have been described.5,6 The following is believed to be the first reported instance of the mycelia of Aspergillus forming an obstructing cast of the renal pelvis. The presence of diabetes mellitus and Addison's disease is of additional interest. Report of Case A 27-year-old white woman with known diabetes mellitus was admitted to Cook County Hospital for the first time on Nov. 4, 1960, with complaints of fever and frequent insulin reactions. She had had labile diabetes since the age of 6. She had required as much as 80 units of isophane insulin daily
