Code Status case · Beginner · Premium
Arm redness in a 41-year-old woman
“This red patch keeps getting bigger. It's been two days. It feels hot and it hurts.”
“Two days of worsening redness and swelling of the left forearm. Temp 99.8, otherwise normal vitals. She came straight from work and looks well.”
Your challenge
A red, hot, painful arm looks like one problem and can be five: a skin infection, a pocket of pus, a rash from something she touched, an inflamed surface vein or a clot deeper down. Megan came straight from work and looks well, but the red patch has been growing for two days. What you see on the skin decides which antibiotic, if any, and whether a needle or a scalpel belongs in the plan. Most of the skill here is knowing what not to do.
After the case, Attending’s Notes explains the decisions that mattered, backed by 8 sources.
Ready to make the call?
Two cases are free. This one is part of Premium.
Spoiler: the diagnosis and what this case teaches
Diagnosis
Uncomplicated Cellulitis
Lesson 1
Make Sure It Is Actually Cellulitis
A red limb is a description, not a diagnosis.
- Spreading warmth in one tender limb fits cellulitis
- Bilateral red legs should make you question cellulitis
- An itchy contact rash suggests dermatitis
- Confirm infection before prescribing antibiotics
Lesson 2
Pus Changes Antibiotics and May Need Drainage
Pus points to staphylococci. No pus points to streptococci.
- Treat streptococci in cellulitis without pus
- A drainable abscess needs incision and drainage
- Use ultrasound when an abscess is uncertain
- Treat MRSA when specific risk factors are present
Lesson 3
Necrotizing Infection Is a Surgical Emergency
Severe pain can appear before dramatic skin changes.
- Pain out of proportion can signal necrotizing infection
- Rapid spread with toxicity suggests deep infection
- Normal labs cannot exclude necrotizing infection
- Likely necrotizing infection needs surgery, not imaging
Lesson 4
Stable Cellulitis Usually Goes Home
Assess the skin findings and the patient’s overall condition.
- Mild uncomplicated cellulitis usually goes home
- Early redness does not prove antibiotic failure
- Systemic illness or rapid spread warrants IV therapy
- Use risk factors to guide antibiotics and admission
In the app, every line above opens into the detail behind it: doses, pitfalls and the evidence, with 8 sources linked to the originals.
Related cases
All 30 casesMegan is a fictional patient. Code Status is for training only and is not intended for real-world patient care, diagnosis, treatment, or clinical decision-making.