Missed!

I have a "mystery patient". She developed a very strange type of "rash". It's not a rash, actually. She had "purpura". These are little tiny bleeds that occur into the skin for no reason. It has absolutely nothing to do with Neurology. She has a "great" internist. She went to see one of the Oncology (Cancer) people about this, because it can be related to a problem with clotting (usually a platelet problem). She had a bone marrow biopsy, and he gave her a chemo drug, but it didn't help. She also went to an Arthritis doctor because sometimes this is from an auto-immune disease (diseases like Lupus and Rheumatoid Arthritis). She had two skin biopsies and a trip to Moffitt Cancer Center and Mayo Clinic. She came back to see me yesterday, still with no diagnosis.
I told my wife to figure out what was wrong with her. I said it's one of three things: Cancer, Immune problem or drug reaction.
Five minutes later she asked me "Please don't make fun of me. I came up with something, but I know it's really stupid". Then she asked me if it could be from Hydrochlorothiazide.
Hydrochlorothiazide is one of the oldest and most commonly used medications for hypertension. It is practically like aspirin in terms of how well known and commonly used it is. It is right on the list of side effects: "purpura". Not one of the at least ten doctors she's seen who are "purpura" experts has taken her off this medication. Last night, I spoke with a hypertension expert. He said he was shocked. He told me that this is so important that it is a question on every medical boards examination. The first thing that should have been done is to take her off the medicine. He was certain that this is the cause.
I don't know if the purpura is from the Hydrochlorothiazide. I suspect it is. We'll know pretty soon (I told her to stop it). However, even if she doesn't get better and it wasn't from the Hydrochlorothiazide, it's prett scary that this was missed. The really scary part is who missed it. It's really amazing how usually it's the simplest things that people make mistakes about. Everyone forgot to look up the side effects of the medications she was on. It's one of the first things that we're supposed to do. That probably should have been done before the bone marrow, chemotherapy, and skin biopsies.
Things can really get missed!