One of the most overused cliches in medicine is the oft referenced: "When you hear hoofbeats, think horses, not zebras."It's a valid reasoning in which to guide one's thought processes. After all, common things are common, uncommon things... aren't. But part of the responsibility of a physician also is to provide comfort and reassurance. It's our job to think "worst case scenario," to work up patients for those conditions, and provide reassurance when evidence is sufficient to quell our suspicions. Another common phrase in medicine is "until proven otherwise." Vaginal bleeding in a postmenopausal woman is cancer until proven otherwise. Acute onset of dyspnea or hypoxemia is a pulmonary embolism until proven otherwise. Severe epistaxis in an adolescent is a nasopharyngeal angiofibroma until proven otherwise. I recently had two patient who elucidated just how true this axiom can be.
A 62 year old woman presented with lateral chest pain of two weeks duration. On physical exam, her pain seemed very musculoskeletal in nature. Pain to palpation, pain on deep inspiration and with sneezing/cough, etc. The horse in this situation is a simple intercostal muscle strain. Regardless, we ordered a chest xray which showed ambiguous opacification of her right lower lung. It just didn't quite add up with the lack of any pulmonary symptoms. So, congresspersons and escalating health costs be damned, we decided we couldn't quite be comfortable with just writing things off, and sent the patient off with a referral for a CT scan and instructions for prn ibuprofen and heat. We saw her back today. The CT scan showed findings pathognomonic for lung cancer. Turns out, her pain was musculoskeletal in nature, as the cancer had begun to invade into her 8th rib. It had also spread to her spine. Zebra. Ironically, the patient returned to say that the heat and ibuprofen had really helped with the pain. If it wasn't for the CT, she would have been sent on her way with the belief that it was all just an intercostal muscle strain, while the cancer continued to grow in her chest.
A 22 year old woman presents with a painful unilateral cervical lymphadenopathy which had been present for 1 month. The horse in this situation is some form of infectious etiology: mononucleosis, cat-scratch fever, occasionally HIV (though this didn't jive with her history). She had been to several urgent care centers, and, going with horses instead of zebras, prescribed two antibiotic regimens, with no improvement of her symptoms. There was still a high likelihood her neck mass was viral in etiology, but we ordered a chest xray "just in case." It ended up showing an extensive mediastinal mass. One biopsy later, the diagnosis returned nodular sclerosing Hodgkin's. Zebra. Luckily, her prognosis is excellent and the delay in diagnosis likely will have no significant effect on her therapy. But it is never easy telling a previously healthy 22 year old that they have cancer, and there is a certain level of embarrassment that it took 5 visits to a physician to reach a diagnosis.
I think the most telling thing I've taken away from these experiences is how important the differential diagnosis remains in clinical practice. Most common symptoms can be attributed to the relatively benign conditions that afflict the gross majority of the general population. But it is important to always consider what else can be consistent with a clinical picture that is truly dangerous, as just because a condition is rare does not mean it cannot be affecting the patient sitting in front of you. Bacterial pharyngitis is common and fairly benign. A retropharyngeal abscess is not, and can often present identically. It is the responsibility of the clinician to use their clinical judgment and work up a patient to the point that they can confidently feel the patient is safe in the context of their illness.
After all, just one day, you may come across a zebra in downtown New York.
3 comments:
Good post, you make some very good points. I do have one comment regarding your patient with lymphoma and your implied censure of the other docs she saw who didn't make the zebra diagnosis. There is an element of "watchful waiting" in medicine. Your paitient could very well have had mono. It would have been bad medicine to proceed directly to biopsy. As it was, she was given time for her condition to resolve, and when it didn't, further investigation was warranted. Of course, watchful waiting is made more difficult when individuals don't have a primary care doc refereeing their care, and when they see 5 different physicians who aren't communicating with each other.
True. I think there were 2 things that bothered me about her case.
(1) No one had ever expressed an appropriate level of concern to her. Especially in the context of an urgent care visit, where there is not the same level of follow-up, even the simple phrase "Now, if you notice the lump in your neck getting bigger and your pain increasing, be sure to seek medical attention quickly because that is very concerning" would have made a difference. She was really blindsided by the lymphoma diagnosis, which shouldn't have needed to happen considering it was her 6th engagement with care for her illness.
(2) She came in on doxycycline because one of the docs from one of her urgent care visits was treating her for bartonella, a pretty obscure diagnosis in and of itself. If you've ruled out viral infection enough in your mind to empirically treat for bartonella, shouldn't a chest xray also be warranted? I mean, unilateral neck mass in a young 20-something female is so CLASSIC for lymphoma. If you've moved past EBV/CMV on your differential, there has to be some obligation to quickly look for it, especially with such a simple procedure as a CXR.
You are so right. Great post.
I was a 23 year old female with a right axillary mass when I went to see my pcp. The only reason I went was because I liked him (he'd been our family doc since I was 1 year old) and hadn't seen him in a while and thought it would be a good excuse to catch up.
He found additional cervical nodes that I hadn't noticed. He also thought mono, testing me three times over 4 weeks. Mono tests were negative and all blood work was "within normal range." (unusual, but possible with Lymphoma).
After the third visit in 4 weeks (I returned at his insistence, wouldn't have otherwise), he sent me for biopsy. Lymphoma. I was lucky. I had a good relationship of long standing with my doc. He was the one to follow up with me after the third visit. I had begun to feel that a fuss was being made over nothing when all I had wanted was to check in with my favorite doctor. I was willing to let it drop. He knew the possibilities. He knew it could be important.
This just goes to show the importance of relationship in treating patients. It was the relationship that got me to the doctor in the first place. It was the relationship that kept me coming back. It was the relationship that had him following up with me, when I was ready to let it go.
I know how difficult medicine is, and how easy it is to dismiss a patient. It's a lot of responsibility. Every interaction with a patient matters. The repercussions are unquantifiable. It might be years in the making, but at some point, that long-past encounter will be a matter of life and death.
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