“I can’t shake this fever…” – Clinical Reasoning Through 3 Common Fever Cases

🩺 Mock Patient Script – Fever Case 1

💬 “It started with a sore throat, then this high fever…”

🚪 Doorway Information

• Age/Gender: 19-year-old female
• Chief Complaint: Fever and sore throat for 5 days
• Vital Signs: T 38.9°C / HR 92 / BP 110/72 / RR 16 / SpO₂ 98%

🗣️ Structured History

Opening: “I’ve had a really sore throat and high fever since a few days ago.”

Shoreline: Started 5 days ago with mild fatigue and sore throat. Fever developed on day 2 and has persisted.

• Onset & Course: Gradual, worse at night, no rash or cough
• Associated Symptoms: Severe sore throat, tender neck glands, mild headache, no GI or chest symptoms
• Mood/Appetite/Sleep: Fatigue, poor appetite, disturbed sleep
• Medical History: Healthy, no medications, ibuprofen helped a bit
• PAM HITS FOSS: No allergies, no hospitalizations or surgeries. Family: Mother had mono. Not sexually active. Non-smoker.
• Concerns: “Is this strep throat or COVID? Do I need antibiotics?”

🩺 Physical Examination

• General: Appears tired but not toxic
• HEENT: Tonsillar exudates, posterior cervical lymphadenopathy
• Chest: Clear
• Abdomen: Mild LUQ tenderness
• Neuro: Alert and oriented

🧠 Differential Diagnosis

• Most likely: Infectious Mononucleosis (EBV)
  • ✔️ Fatigue, pharyngitis, posterior nodes, LUQ pain
  • ❌ No rash (yet), no hepatomegaly on exam
• Streptococcal Pharyngitis
  • ✔️ Fever + tonsillar findings
  • ❌ Less likely due to age, fatigue, node pattern
• Acute HIV Seroconversion
  • ✔️ Fever, pharyngitis possible
  • ❌ No risk exposure, no rash

🪞 Clinical Reflection

This case aligns closely with EBV. The key lies in recognizing the typical triad: sore throat, posterior lymphadenopathy, and fatigue. LUQ tenderness may suggest splenomegaly, requiring activity restrictions.

💡 Clinical Pearls

• 💡 Posterior nodes → think mono
• 💡 Ampicillin rash = clue to EBV
• 💡 Avoid contact sports for 3–4 weeks
• 💡 Monospot test may be falsely negative early
• 💡 EBV can mimic strep — but fatigue & age are clues

❓ Challenging Questions

Q: “Could this be strep throat? Should I take antibiotics?”
A: “That’s a good question. Strep is possible, but your symptoms fit mono better. We’ll test to be sure. If it’s viral, antibiotics won’t help—but we’ll focus on relieving your symptoms and recovery.”

Q: “Can I go back to class tomorrow?”
A: “You may still feel weak, so rest is important. Once your fever settles and energy returns, it’s okay to return gradually. No contact sports for now—we need to protect your spleen.”

📝 SOAP Note

S: 19F presents with 5-day history of sore throat and fever. Fatigue, poor appetite, and posterior neck swelling noted. No GI or respiratory symptoms.

O: T 38.9°C, HR 92. Tonsillar exudates, posterior cervical lymphadenopathy, mild LUQ tenderness.

A:
# Fever + sore throat + fatigue
# Posterior cervical nodes
# Possible splenomegaly (LUQ pain)

ddx): EBV, strep pharyngitis, acute HIV  
r/o): COVID, influenza (no exposure or myalgia)

→ Likely infectious mononucleosis. Will confirm with Monospot/EBV serology. Advise supportive care and activity restriction.

P:
- EBV/Monospot test
- Fluids, acetaminophen
- Avoid contact sports ×3–4 weeks
- Follow-up if worsening or abdominal pain

🩺 Mock Patient Script – Fever Case 2

💬 “I thought it was just a UTI, but now I’m shaking all over…”

🚪 Doorway Information

🩺 Mock Patient Script – Fever Case 3

💬 “This fever keeps coming back… it’s been almost a month.”

🚪 Doorway Information

• Age/Gender: 63-year-old male
• Chief Complaint: Recurrent fever for 3+ weeks
• Vital Signs: T 38.0°C / HR 88 / BP 124/76 / RR 16 / SpO₂ 98%

🗣️ Structured History

Opening: “It comes and goes. I feel okay sometimes, but then the fever hits again.”

Shoreline: Low-grade fevers have been recurring for over 3 weeks. No clear triggers.

• Onset & Course: Gradual onset. Fever peaks at night (up to 38.5°C), sweats overnight, some fatigue. No chills or rigors.
• Associated Symptoms: 4-kg weight loss, night sweats, mild dry cough, no hemoptysis, no pain, no urinary or GI symptoms
• Mood/Appetite/Sleep: Low energy, poor appetite, waking up sweaty
• Medical History: Hypertension, latent TB treated 15 years ago. No recent travel.
• PAM HITS FOSS:
  • Allergy: None
  • Medication: Amlodipine
  • Family: Father had lymphoma in his 70s
  • OBGYN: N/A
  • Sexual history: Monogamous
  • Social: Retired teacher, lives alone, ex-smoker, no alcohol
• Concerns: “I’ve had blood tests and even a CT, but nothing came up. Could it be something like cancer?”

🩺 Physical Examination

• General: Thin, fatigued, but no distress
• HEENT: No lymphadenopathy, oropharynx clear
• Chest: Mild bibasilar crackles
• Abdomen: Soft, mild splenomegaly, no masses or tenderness
• Neuro: No focal deficits

🧠 Differential Diagnosis

• Most likely: Lymphoma (esp. Hodgkin)
  • ✔️ Fever >3 weeks, weight loss, night sweats (B symptoms)
  • ❌ No lymphadenopathy on exam (may be deep)
• Tuberculosis (reactivation)
  • ✔️ Dry cough, prior TB, night sweats
  • ❌ No known exposures, no clear pulmonary findings
• Adult-onset Still’s Disease
  • ✔️ Recurrent fever pattern, weight loss
  • ❌ No rash, arthritis, sore throat

🪞 Clinical Reflection

This is a textbook FUO. The absence of clear localizing signs despite constitutional symptoms raises concern for malignancy or atypical infections. Lymphoma remains high on the list. Further workup including PET-CT, repeat labs, and possible lymph node biopsy may be needed.

💡 Clinical Pearls

• 🔍 FUO: >38°C for >3 weeks, undiagnosed after 3 days inpatient
• 🌙 B symptoms = fever, weight loss, night sweats → think lymphoma
• 🫁 TB can be extrapulmonary or reactivated decades later
• 📉 Malignancy may present subtly, especially in elderly
• 📈 ESR/CRP elevation is common but nonspecific – repeat if symptoms persist

❓ Challenging Questions

Q: “Is this cancer?”
A: “That’s one possibility, but we need more information. There are several other conditions that can cause this. We’ll do the right tests to rule things out. You’re not alone—we’ll go through this step by step.”

Q: “Why haven’t the previous tests found anything?”
A: “That’s a very valid concern. Sometimes, the cause of a prolonged fever isn’t obvious early on. Some conditions develop slowly or are hard to detect at first. We’ll continue investigating until we find the answer.”

📝 SOAP Note

S: 63M with 3+ weeks of intermittent fever, night sweats, 4-kg weight loss. No cough or GI symptoms. Past TB, father had lymphoma.

O: T 38.0°C. Thin appearance. Bibasilar crackles, mild splenomegaly. No lymphadenopathy or focal findings.

A:
# Fever of unknown origin >3 weeks
# Weight loss and night sweats (B symptoms)
# Suspected lymphoma vs reactivation TB

ddx): Lymphoma, TB, Still’s disease, subacute IE  
r/o): UTI, pneumonia, viral infections (normal labs/imaging)

→ Further workup for FUO. Malignancy and TB are high on the list. PET-CT or bone marrow biopsy may be required.

P:
- CBC, ESR, CRP, LDH, ferritin, HIV test, blood cultures
- Chest CT + consider PET-CT
- TB PCR / Quantiferon
- Oncology and ID consult