1. Problem Representation
Teaching slides based on:
Keenan CR, Dhaliwal G, Henderson MC, Bowen JL.
A 43-year-old woman with abdominal pain and fever.
J Gen Intern Med. 2010;25(8):874-7.

2. Problem Representation
One-sentence summary highlighting the defining features of a case, helping clinicians generate a differential.
Answers the following 3 Q’s:
Who is the patient?
What is the temporal pattern of illness?
What is the clinical syndrome?
Teacher’s guide
Definition of PR:
Ask what the key ingredients of a problem representation are, can then click to reveal the 3 questions, and discuss examples of the kind of information that should be included
Who is the patient? What are the pertinent demographics and risk factors
What is the temporal pattern of the illness? What is the duration (hyperacute, acute, subacute, chronic) and tempo (stable, progressive, resolving, intermittent, waxing and waning)
What is the clinical syndrome? What are the key signs and symptoms

3. Problem Representation: Example
A middle aged man with acute onset pleuritic chest pain, shortness of breath, and hemoptysis after a total knee replacement.
Pertinent demographics/risk factors
Middle aged man
Recent total knee replacement
Length/tempo
Acute
Key signs/symptoms
Pleuritic chest pain, shortness of breath, hemoptysis
Teacher’s Guide:
Ask trainees to dissect the one-liner – how have the 3 questions been answered? Can then click to reveal the table.
Make explicit that all 3 questions must be answered to efficiently and effectively solve a clinical problem.

4. HPI
A 43yo Mexican woman presented to the Emergency Department with 1 week of abdominal pain, fevers to 38.9, intermittent frontal headache, and 2 days of LUQ pain.
The pain was sharp, constant, and radiating to the mid-epigastrium, RUQ, and left flank.
Episodic N/V
No change in pain with eating, no hematemesis, dysuria, or diarrhea
No photophobia or other neurologic symptoms
Not sexually active
Teacher’s Guide
Of note, for simplicity, we have excluded a detail found in the original case from the history above: One day prior the patient had been diagnosed with gallstones at another ED and treated with oral metoclopramide and hydrocodone-acetaminophen.
For advanced learners, this additional piece of history could be revealed after the initial problem representation is given, and trainees could be asked how/whether this information would change their problem representation. Including this detail can be an opportunity to talk about the fact that when a prior presumptive diagnosis is known, it can sometimes lead us astray.

5. What is your initial problem representation?
HPI
Case Continued
What is your initial problem representation?
Examples
Differential Triggered
A 43yo woman with fever, headache, and associated LUQ abdominal pain and N/V
CNS pathology becomes primary concern
A 43yo woman with acute onset of sharp LUQ pain, N/V, and associated headache
GI pathology becomes primary concern
Teacher’s guide
*** Consider keeping a running list on a white board of the sequential problem representations generated by the group throughout the case; under each one-liner, you can list the diagnoses that are triggered.
Ask: What is your initial problem representation? Consider starting with the most junior learner, and then asking more senior trainees if there is anything they would add/subtract from this initial one-liner. Ask learners to try giving more than one problem representation and to consider how these different one-liners impact their diagnostic thinking.
Answer: Given the complexity of the case, we can consider more than one problem representation to create broad differential diagnoses, for example:
A 43yo woman of reproductive age with fever, headache, and associated LUQ abdominal pain and N/V -> CNS pathology becomes primary concern
A 43yo woman of reproductive age with acute onset of sharp LUQ pain, N/V, and associated headache -> Gl pathology becomes primary concern
Ask: What are the components (i.e., epidemiology, clinical syndrome, and tempo) of the problem representation in the examples we’ve created?
Ask: What are the differential diagnoses prompted by different problem representations?
For more advanced learners, after this initial discussion can be a useful time to pause and ask the group to consider how much a given problem representation can lead the team down a certain path – can ask trainees if they’ve ever had an experience of being given a one-liner that had them thinking along a certain diagnostic pathway, which later they realized was the wrong direction to be heading. Why? Was key information missing from the problem representation, or was the wrong information highlighted?

6. Additional History
ROS: + night sweats, 20lb intentional weight loss in several months
Meds: Acetaminophen
SH:
No alcohol, tobacco, or drug use.
Born in Mexico, immigrated to US at age 23.
Travels to Mexico regularly, and returned 3 weeks ago after a 2 month visit.

7. What is your updated problem representation?
Case Continued
What is your updated problem representation?
43-year-old woman with recent travel to Mexico presents with diffuse abdominal pain and a subacute history of night sweats and weight loss.
Teacher’s guide:
The point of this slide is to demonstrate that the problem representation should be updated iteratively as the clinician gathers data throughout a patient encounter.
Ask: What would they decide to include in their updated problem representation? i.e.: Travel to Mexico raises possibility of infections like tuberculosis.
Example of an updated PR (can click for all to see): “43-year-old woman with recent travel to Mexico presents with diffuse abdominal pain and a subacute history of night sweats and weight loss.”
With experience and deliberate practice clinicians learn to incorporate new and relevant findings into the problem representation. Updated problem representations, in turn, lead to a prioritized and refined (expanded or narrowed) differential diagnosis as a case moves forward.
Ask a trainee what they would focus on during the physical exam. This question forces the trainee to consider how a focused physical exam might impact the differential being considered.

8. Physical Exam T 38.1°C, BP 96/43 mmHg, HR 125, RR 16
Gen: Moderate distress
HEENT: + scleral icterus
CV: tachycardic, no m/r/g
Abd: Nondistended, diffusely tender, especially LUQ. No rebound or guarding. Liver span 15cm to percussion. Spleen not palpable. No CVA tenderness.
Pelvic, neurological, and skin exams normal
Teacher’s guide:
Ask: “How does the physical exam change your differential diagnosis?” A trainee might comment on two new relevant findings: jaundice and hepatomegaly.
After these observations, ask a trainee to provide an updated Problem Representation (i.e., do any of the physical exam findings deserve to be included?)
Example of updated PR: “43-year-old woman, with recent travel to Mexico, with acute LUQ pain, fever, jaundice, and hepatomegaly.”
At this point, with these updates in the PR, a primary CNS-syndrome (like meningitis) is far less likely. it is important to explicitly highlight the need to adapt PRs, especially in a complex a case. Here the jaundice and hepatomegaly focus pathology to the liver.
Ask: “What labs and imaging would you order, and why?” Keep forcing the trainees to think aloud. This discussion can also be an opportunity to promote cost-conscious medicine.

9. Labs Hemoglobin 12.5 (MCV 75) WBC 8,300 Neutrophils 66% Lymphocytes
31%
Monocytes 3%
Platelet count
88,000
AST
334
ALT
133
Alkaline phosphatase
301
Total bilirubin
5.1 (direct 3.4)
Albumin
2.3
INR
1.2
Lipase 25
Urine
WBC 22
RBC 14
Casts
Granular, hyaline, WBC
Protein
moderate

10. Imaging Abdominal u/s: mild hepatosplenomegaly
mild gallbladder wall thickening, & pericholecystic fluid
No gallstones or biliary ductal dilatation.
CXR without focal consolidation.

11. What is your updated problem representation?
Case Continued
What is your updated problem representation?
Teacher’s guide:
The point of this slide is to (again) demonstrate that the PR should be updated iteratively as the clinician gathers data throughout a patient encounter.
Example of an updated PR: 43-year-old woman with recent travel to Mexico, p/w a subacute illness associated with weight loss, night sweats, SIRS, prolonged fever, LUQ pain, hepatopathy and thrombocytopenia.” For practice consider excluding “Mexico” from the PR and ask trainees whether including or excluding this detail impacts their differential.
Ask: “Why did they choose to include/exclude certain details? How does this new PR affect their differential?”
Ask: “What level of care would you admit the patient to? What would be your next step in management (both diagnostically and therapeutically)?”

12. Case Continued
The patient was admitted for presumed cholecystitis and treated with ceftriaxone and metronidazole.
Teacher’s guide:
Consider asking whether trainees agree with this management? Why or why not?

13. Case Continued CT of the abdomen: mild hepatomegaly mild splenomegaly
heterogeneous spleen with small hypodense lesions
Teacher’s Guide:
Pause to ask trainees how this imaging impacts their differential

14. Case Continued A HIDA scan was normal.
The patient continued to have fevers.
Hepatitis A, B, & C, HIV, RPR & a PPD were negative.
Multiple blood and urine cultures were negative after 2 days.
Teacher’s Guide:
- Ask your learners if they understand why a HIDA scan was ordered
- Ask learners, ‘How do the lab tests and negative cultures change your differential diagnosis?’

15. What is your updated problem representation?
Case Continued
What is your updated problem representation?
43 year old woman with multiple small hypodense splenic lesions, fever, LFT abnormalities and hepatosplenomegaly
Teacher’s guide:
Ask: “What is your update PR?”
Possible answer: “43 year old woman with multiple small hypodense splenic lesions, fever, LFT abnormalities and hepatosplenomegaly.”
The updated PR should raise the possibility of infiltrative or embolic processes.
Expert’s Differential Diagnosis: culture-negative endocarditis, TB, histoplasmosis, coccioidomycosis, brucellosis, Q fever and bartonella infection, which can all present with granulomatous involvement of the liver and spleen.

16. Case Continued Stool ova, parasite & AFB exams negative
Sputum AFB stains negative
ANA & anti-mitochondrial antibodies negative. Anti-smooth muscle antibody 1:40
SPEP normal
Teacher’s guide:
Ask: “What would be your next step?”

17. Liver Biopsy
Hepatitis with infiltration of chronic inflammatory cells and non-caseating granulomas
Stains negative for fungal and acid fast elements
Teacher’s guide:
- Core needle biopsy was performed.

18. What is your final diagnosis?
Case Continued
What is your final diagnosis?
Teacher’s guide:
- Answer: Brucellosis (see next slide)

19. Case Continued
On the 4th hospital day, blood cx returned positive for Brucella melitensis.
Doxycycline & rifampin resulted in rapid improvement.
Brucella serology later returned positive for IgM Ab.
Patient completed a 6-week course of antibiotics and did well.
Further history revealed that when visiting her home in rural Mexico, the patient often milked the family cows.

20. Final Problem Representation
Young woman from rural Mexico with recent exposure to cows presents with fever, thrombocytopenia, multiple splenic lesions and granulomatous hepatitis.
Teacher’s guide:
Experts continuously re-frame the case and update the problem representation. Throughout this case, we updated our problem representation. Here is a final problem representation which triggers the right diagnosis.
The social history is often a key discriminating feature in febrile illnesses, especially for patients who are born outside the U.S., and/or for patients who travel, particularly outside of industrialized areas where they may be exposed to unusual infections.
By asking about these exposures and including these key aspects of social history in the problem representation, clinicians can much more quickly consider the correct diagnosis.

21. Case Continued Diagnostic tier Diagnostic considerations
I (close match)
Brucellosis
Ib (potentially fatal in 24h; variable match)
Cholangitis (acute presentation)
II (intermediate match)
Lymphoma, Q fever, tuberculosis, histoplasmosis
III (limited match)
Sarcoidosis, SLE, alcoholic hepatitis, cholecystitis, autoimmune hepatitis
Teacher’s guide:
This differential diagnosis is a reflection of the problem representation on the previous slide
Clinicians prioritize diagnoses by the degree to which diseases match the working problem representation2

22. Human Brucellosis Very common illness worldwide
Transmitted by direct contact with infected animals (cattle, sheep, goats, pigs), or by consuming unpasteurized dairy products
Usually presents with nonspecific symptoms including undulating fevers, night sweats, malaise, weight loss & arthralgias
Can present with focal syndromes – meningitis, arthritis, endocarditis or epididymoorchitis
Teacher’s guide:
Four brucella species – melitensis, suis, abortus, and canis – cause the majority of human illness, with B. melitensis being the most common
The incubation period is days to months

23. Differential of Granulomatous Hepatitis
Infections: TB, histoplasmosis, coccidioidomycosis, Q fever, brucellosis, syphilis, cryptococcosis, leprosy
Malignancy: Lymphoma, renal cell carcinoma
Autoimmune: Sarcoidosis, primary biliary cirrhosis
Drugs
Idiopathic
Teacher’s guide:
- Up to 20% of cases are idiopathic

24. Credits
Teaching slides are based on: Keenan CR, Dhaliwal G, Henderson MC, Bowen JL. A 43-year-old woman with abdominal pain and fever. J Gen Intern Med. 2010;25(8):874-7.
This work by J Olenik, J Kohlwes, R Sedighi Manesh, DM Connor is licensed under a Creative Commons Attribution-NonCommercial- ShareAlike 4.0 International License

25. References
Bowen JL. Educational strategies to promote clinical diagnostic reasoning. N Engl J Med. 2006;355:
Lucey C. ADPIM National Meeting. Philadelphia; 2000.
For additional references and reading related to Problem Representation, see Problem Representation Overview