It just means that the doctor has not specified what type of cancer cells, what caused the pneumonia (bacterial, viral, fungal, location, etc), what caused the HTN. When people put in codes from the ICD-9 code book (for insurance purposes), they either have to know specifics such as rt lower lobe pneumonia caused by a specific bug, or else they just put the general code number for "He has pneu, but I have no idea what kind or where it is...just pay for it b/c he is really sick" number.
Don't feel bad. I kept seeing NSTEMI as a dx until it drove me nuts. I even asked several docs who didn't know. Finally found a doc from a large hosp in the city who could tell me. Non st elevated myocardial infarction.