When you hear hoofbeats, think horses, not zebras. Mostly true.

But if zebras are more common in the geographical area where you are at the time, then do, please think about zebras. But I digress.

57 year old female presented to the ED with chest pain, sudden onset, associated with shortness of breath, referred to us in acute medicine (yes a lot of my talks have been acute medicine related, those are the wounds that are freshest!) to rule-out-slash-treat-for a PE (pulmonary embolism, or a clot on the lungs). So I went through the motions, history, physical exam, investigations etc. Her past history was significant for dual malignancies (breast AND colorectal, both treated with surgery and chemo/XRT as needed quite a few years back). This history is what had freaked A&E out and had sent her in our direction (we OK, she was high risk for it, but I digress again).

Her D-dimers were not elevated, which basically is a test to rule in or rule out a PE (it being positive could be for a number of reasons, including a PE, but it being negative in her case basically ruled out the possibility of a clot). Her observations (or vitals, as we called it in the good old days) were all within normal limits, so her oxygen levels and her heart rate and her blood pressure and her cooking abilities were all top notch. Well the last one wasn’t (I mean it may have been top notch but it wasn’t a vital observation. Wow, I should get a degree in digression). Her pain had since then subsided, and all the rest of her blood tests including those for infection etc like a white cell count, and a CRP (both markers for infection, something that would cause her chest pain if the infection were focussed in her chest) were also within normal limits. And to top it all, her troponins were not raised either (serially done, these are enzymes which leak out into the blood to signify myocardial damage – myocardial = heart muscle), so it essentially looked like she was ready to go home.

For every symptom or complaint that a patient has, doctors and nurses and other allied healthcare professionals are trained to go through a checklist, usually a mental one (or physical, if you like to tick off or cross things off a physical paper list) of things that can cause the afore-mentioned symptom/complaint. Another checklist that they have is of a list of investigations or manoeuvres or steps that need to be taken in order to rule in or rule out certain diagnoses. This will basically decide whether or not a patient is safe to be sent home with just reassurance, or the condition warrants further investigation but non urgently and can still be safely sent home now, to be called in for outpatient investigations and assessment at a later point, or can not be sent home at all, and would benefit most from urgent or in-hospital investigations/assessments/services. As part of the checklist of ‘chest pain’, there are innumerable causes, and as part of the workup of significant chest pain (significant being a vague term, but significant enough to warrant a trip to the doctors’ or ED or to seek medical advice) a chest X-ray is very important. I had requested the chest X-ray for this patient (or ED had done so, and I took credit for requesting it, sue me) and the consultant who did the post-take with me on this patient agreed that she could indeed go home, once the chest X-ray had been done, and unless there was something absolutely horrific on it, he saw no reason for the patient to stay in. And you can well imagine, I am not writing this post just for the heck of it (well, partly, but I do have a point) and it was related to this chest X-ray, and this is where horses and zebras and hoofbeats make a cameo. But not for the reasons you probably think.

The patient came back from her chest X-ray, I looked it up, and I saw (as you may have probably guessed by now) a huge stinking mass in her right mid and upper zone of the lung. OK my radiology colleagues (and possibly most of my other colleagues) would kill me for not saying this right; I will rephrase: There was an well-defined opacity in the right lung encompassing the right mid and upper zones, extending from the hilum medially to the chest wall laterally.It could be a pneumonia but hey, with everything under the sun being normal for her and keeping in mind her strong prior history, my mind jumped to the possibility of it being a malignancy. More like…probability of it being a malignancy. I took a deep breath to calm myself, before I could step behind the curtain to break the bad news to this grandmother of 2. I was about to do so, when the consultant rounded the corner and asked me about the x-ray. Thankfully, I took him round to have a look at the X-rays before I broke the news to this patient, because this is where the twist came (and here you thought the twist had already come and gone, and that the mass on the chest X-ray in an otherwise completely normal looking patient was the twist. No it wasn’t as you are thinking, or as I thought. And boy, am I glad I was wrong!)

The consultant took one look at the x-ray (this is after I had told him that I had found something horrible on the X-ray, it could be a pneumonia but very likely a mass that needs to be biopsied etc…) and then placed his open palm very delicately to the middle of his forehead and very matter-of-factly said the magical words: “Have you asked the patient if she has had a breast implant?” My jaw dropping to the floor and my deer-caught-in-the-embarassed-headlights look told him I hadn’t. I went and asked the pleasant question (seriously, the things we want to know about!), and sure enough, she had had a mastectomy 7 years back for her breast cancer, followed by an implant. The totally non-threatening implant that I saw on the X-ray and mistook for a life-threatening infection and/or a life-threatening malignancy. The patient smiled. I smiled. The consultant laughed (cackled more like, rubbing his hands together with glee. OK I may have imagined that last part, because he was thoroughly professional, and actually taught me something I had not thought of. Chest X-rays or just any X-rays in general, just make sure you think of anything on or under the patient’s body causing that shadow, before you jump to the worst possible conclusion, for the patient, but like in this case more so for you. Very common ones are metallic sequins looking like metastatic nodules on lung; bra-hooks being mistaken for evidence of cardiac surgery; and when yours truly had the case of the misunderstood breast implant. Sheesh!

PS: I realize all the examples I have provided were related to female patients. Please don’t call me a chauvinist or start a feminists’ war on the blog. I apologise but it is midnight, and I can not think of any helpful examples from the male population. Maybe men (and their x-rays) are just …easier to read *runs and hides*

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