A 22 year old student presents to the college health clinic with
a one week history of fever, sore throat, nausea and fatigue.
He could hardly get out
of bed this morning.
There are no pets at home.
He admits to having recent unprotected sex.
His vital signs include a fever of 38.3
celsius, a heart rate of 72 beats per minute,
blood pressure of 118/63 mmHg and a
respiratory rate of 15 breaths per minute.
On physical examination, he has bilateral
posterior cervical lymphadenopathy,
exudates over the palatine tonsil
walls with soft palate petechiae
and an erythematous macular
rash on his trunk and arms.
He also has mild hepatosplenomegaly.
Which of the following is
the most likely diagnosis?
Answer choice (A) - rubella
Answer choice (B) -
acute HIV infection
Answer choice (C) -
Answer choice (D) -
and answer choice (E) -
Now take a moment to come to your own
conclusion before we go through it together.
Now let's tackle this question.
This is a 2-step question.
First determine the underlying diagnosis and second,
determine the microbiology behind the underlying organism.
Now let's start with step 1.
let's determine which of the following symptoms we saw in the
clinical vignette are generic or specific to the patient's condition?
While this patient has generic symptoms
such as fever and sore throat and fatigue,
but much more specific are bilateral cervical lymphadenopathy,
palatine tonsil exudates, soft palate petechiae,
erythematous rash on trunks and
arms and also hepatosplenomegaly.
as a whole, these put together, this is more
suggestive of a infectious mononucleosis infection.
Now, we see what is specific
and which is general.
One thing to note here that is also very-high yield is that
the question stem did mention that the patient had fatigue.
Traditionally, in patients that have infectious
mononucleosis, they experience SEVERE fatigue.
So in this case, the clinical vignette said fatigue, so we
place it under the condition of a more generic symptoms.
But if they had mentioned 'severe' fatigue,
then that would have been more of a specific
symptom for infectious mononucleosis
and we could have thought about it in
our more specific symptom category.
Now, now that we've identified which signs and symptoms
that are more specific, and we have a underlying diagnosis,
let's look at step 2 which is really
coming to a firm conclusion regarding
which infectious etiology can produce
the clinical symptoms that we see?
Now this patient has a
history of unprotected sex.
And this of course raises
the risk of an HIV infection.
But this does not generally
present with hepatosplenomegaly
and instead patients with an acute HIV
infection can be either asymptomatic
or they can have skin lesions and
diarrhea as common symptoms.
Now given this patient's age being
a young, college aged-student
and the presentation is very supportive
of infectious mononucleosis,
the infection here really is due to Epstein-Barr
virus as the underlying microbiology of our disease.
Now Epstein-Barr virus is what commonly causes infectious
mononucleosis or also called the "kissing disease".
Now refer to this image regarding the clinical
presentation of infectious mononucleosis,
we see there on the left that we have highlighted several
clinical components that you can see on a patient.
There you have pharyngitis where you
have inflammation of the pharynx.
This is where the patient
gets sore throat.
Now this sore throat
clinically is VERY severe.
Some patients with infectious mononucleosis will
experience such severe difficulty swallowing
that sometimes, they actually have to be hospitalized for IV
fluid administration because they can't take oral intake.
The next thing we see on the image are swollen lymph
nodes, or what's also called 'lymphadenopathy'.
Now what's very specific here is, it was mentioned the
patient has 'bilateral posterior cervical lymphadenopathy'
Now posterior cervical lymphadenopathy is not
specific only to infectious mononucleosis
but with respect to the USMLE step
1 exam and step 2 and step 3,
posterior cervical lymphadenopathy is essentially
a buzz word for infectious mononucleosis.
Now we also see that you can have
splenomegaly, hepatitis or hepatosplenomegaly.
We see there a virus showing
the Epstein-Barr virus.
And we also see the atypical lymphocyte
that are seen with the disease.
So in this case, the correct answer is answer choice (D)
- infectious mononucleosis caused by Epstein-Barr virus.
Now let's go through some high-yield facts regarding
the Epstein-Barr virus and infectious mononucleosis.
Now Epstein-Barr virus is a type of human herpesvirus
that is found in the saliva and in the genital secretions
and it causes what is called infectious mononucleosis
or what was previously called glandular fever.
Now as we know, Epstein-Barr virus is
actually associated with a certain malignancy
called Burkitt's lymphoma -
that's very high-yield to know.
Now infectious mononucleosis also called previously
glandular fever is caused by Epstein-Barr virus.
Now you will most commonly see this
infection in teenagers and in young adults.
And oftentimes, people obtain this
disease and are asymptomatic.
However, in some instances, people become very
symptomatic in which they will have a high fever,
an extremely sore throat that can limit oral intake,
erythematous spots on the mouth or petechiae,
bilateral posterior cervicolymphadenopathy,
and they will have VERY significant
fatigue in some instances