Back to basics: Updating the differential diagnosis with COVID-19 : Cancer Research, Statistics, and Treatment

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Back to basics

Updating the differential diagnosis with COVID-19

Y. Su, Clarice K.Y.; Lik Au, Sunny Chi1,

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Cancer Research, Statistics, and Treatment 5(2):p 302-303, Apr–Jun 2022. | DOI: 10.4103/crst.crst_101_22
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The coronavirus disease 2019 (COVID-19) pandemic has spread far and wide for over two years. The wave caused by the Omicron variant ran rampant as it was a more transmissible but less virulent strain compared to its predecessors, severely affecting all countries.[12] Our city, Hong Kong, was no exception,[3] with almost one-seventh of our population (over a million) infected at the time of this writing in the ongoing fifth wave of the COVID-19 pandemic triggered by Omicron. Despite the first local appearance of Omicron three months ago,[4] our clinic was still open to the public and to walk-in patients with cancer with urgent medical issues.[5]

Mrs A, a 77-year-old lady diagnosed with Fédération Internationale de Gynécologie et d'Obstétrique (FIGO) stage IIB carcinoma of the uterine cervix in 2021[6] had just completed her course of chemoradiotherapy and high-dose-rate brachytherapy. She returned to our clinic with blurring of vision in the right eye and right-sided headache since the previous night. There was no history of trauma or discharge, but she reported nausea without vomiting associated with the onset of her ocular symptoms. On further questioning, she volunteered a history of recent upper respiratory tract symptoms; her husband, whom she lived with in a small flat in Hong Kong, reported similar respiratory symptoms. They had both visited the same general practitioner the preceding day and had been prescribed some antitussives along with other cold medications. Upon enquiry, they admitted that there were a few confirmed cases of COVID-19 in the apartment complex where they lived.[7] Given her history of cervical cancer, she had not received the COVID-19 vaccine.[8]

Examining their cold medications, we found many anti-cholinergic drugs as well as pseudoephedrine in the nasal decongestants. Physical examination of the right eye revealed ciliary injection, a hazy cornea, and a digital ocular pressure of 30 to 40 mmHg, which was significantly higher than that in the left eye which had a normal ocular pressure of ~15 mmHg.[9] Thinking back to my second year of medical school, in which I had attended the basic pharmacology lecture on cholinergic receptors and drugs, the diagnosis of possible glaucoma or acute primary angle closure (APAC) flashed through my mind.[10] However, could a purely ophthalmic diagnosis explain it all? In my junior medical clerkship teaching, I had been taught “One man, One disease.”[11] However, towards the senior medical clerkship, we all learned that the clinical reality was much more complex than any textbook teaching. During housemanship and continuous resident teaching after my graduation, we were always challenged to think one step further. Could Mrs A actually have COVID-19? Since there was an outbreak in their apartment complex, were Mr and Mrs A both infected with COVID-19?

Geographic differences and local epidemiology always affect one's top differential diagnoses.[12] There are multiple examples in oncology, such as nasopharyngeal carcinoma, which one must consider in southeast Asians presenting with nasal symptoms.[13] Another example in this new era is the COVID-19 differential when considering the diagnosis in a patient with an abnormal chest computed tomography (CT) scan.[14] There is no doubt that common things should be considered first,[15] which was another lesson I learned in medical school; and COVID-19 had definitely become common now with around 20,000 new cases reported daily in Hong Kong. Mr and Mrs A subsequently underwent polymerase chain reaction (PCR) testing for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and, as suspected, both tests came back positive.

Ophthalmology colleagues were consulted, and the diagnosis of APAC was established with an intraocular pressure (IOP) of 53 mmHg in the right eye. Mrs A already had a few risk factors: advanced age, female sex, Asian ethnicity, shallow anterior chamber with hypermetropia (wearing +6 Diopters reading glasses), cataract lens,[16] and the attack was precipitated by the cold medications.[1718] IOP lowering medications were promptly started, and the IOP normalized to 11 mmHg the next day.

Graduation from medical school does not signify the end of our education. Lifelong learning builds on our medical school foundation throughout our residency training,[19] and even after fellowships. This is essential nowadays with the aging population and evolving medical environment.[20] With the COVID-19 pandemic, our list of differential diagnoses has to be updated. No longer can the same differential diagnosis list from the past to be unchangingly applicable in the future.[21]

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. The patient has given her consent for the images and other clinical information to be reported in the journal. The patient understands that her name and initials will not be published, and due efforts will be made to conceal her identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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