Author: Lilamarie Moko, MS4 // Editor: Michael Barrie, OSU EM Attending
It’s another late Thursday night in the ED and the waiting room is backed up with patients needing care. As you finish up with your seventh patient presenting with undifferentiated abdominal pain, your eyes rove the board for something new. You assign yourself to a gentleman in his 60s, a “John Doe” with left arm swelling. Hopefully his abdomen has been behaving itself…
Upon entering the patient room, you see a pleasant, comfortable appearing gentleman in his mid-60s. He’s been having left arm pain and swelling that started 6 days ago. His arm is “on fire”. He first noticed some redness in his left elbow, associated swelling, tenderness, and restriction flexion and extension of his elbow. After about a day, he noticed the redness spreading down to his left wrist, with similar swelling, tenderness, and restricted flexion and extension of both wrist and fingers. He’s had a temperature to 100F, diaphoresis and chills. Also he reports some diarrhea, and urinary frequency in the past 2 days. With some further probing, he reveals that he just returned from Florida several days ago, had no noted scrapes or wounds, and spent most of his time fishing. He works as a farmer, but hasn’t been working for the past couple weeks.
His past medical history is significant for TIA, basal cell skin cancer, hypertension, osteoarthritis, and gout. He had a right knee replacement several years. He has a remote smoking history of 20 pack-years, and denies regular alcohol intake.
In the room, his vitals are as follows:
T: 99F, HR: 90, BP: 135/80, SpO2: 100% RA, RR:14
His physical exam findings are as follows:
- Constitutional: comfortable appearing, in no acute distress
- CV: RRR, no murmurs, rubs, gallops, radial pulses intact b/l
- PULM: CTAB, no rhonchi appreciated
- GI: soft, nontender, nondistended
- MSK/Skin: L forearm—erythema 2 centimeters superior to medial/lateral epicondyle, terminating at the wrist, with erythema increasing in severity closer to wrist. L forearm is tender to palpation and warm to touch. Resistance to passive flexion/extension L elbow and wrist. Limited active flexion/extension L elbow, wrist. R forearm WNL.
- Neuro: No radial/median/ulnar nerve deficits appreciated to sensation, motor. No gross motor deficits appreciated.
So what’s your differential diagnosis?
As we know, we should always try to eliminate the life-threatening issues first. Now this patient appears comfortable, so index of suspicion is lower for acute life-threatening issues. However many potentially morbid conditions are on our list.
Possible differential:
- Septic arthritis
- Septic bursitis
- Cellulitis – staph, strep, or marine assoicated such as Vibrio species.
- Gout
- DVT
When I saw his arm, my first suspicion was cellulitis. However, the rule of the game is to always have an open mind when considering diagnoses for patients.
So let’s discuss cellulitis and the great masquerade.
Cellulitis is characterized by warmth, erythema, and edema at the site of infection, usually a break in the skin barrier. It typically is unilateral, usually restricted to the lower extremity. The course is typically indolent with some localized symptoms. A mild fever may be present. Marine exposures can lead to Vibrio vulnificus infections and other unique marine infections. These can be particularly invasive and are more likely to lead to sepsis.
But when is it not just cellulitis?
- Watch out for: additional symptoms, like joint swelling and pain, limited ROM—this could be cellulitis with underlying septic arthritis
- Use synovial fluid sample to diagnose. If the patient has limited passive ROM, then a joint aspiration is indicated. Approach the joint through an area of skin that does not appear to be infected.
- Watch out for: chronic soft tissue infection refractory to antibiotics—this could be cellulitis with underlying osteomyelitis
- Use radiographic imaging to diagnose. Xray is a reasonable start, but may need MRI to confirm diagnosis. This diagnosis can generally be made as an outpatient.
- Watch out for: monoarticular joint pain—this could be acute gout
- Very difficult to differentiate from septic joints. On synovial fluid analysis would should have crystals, and potentially less WBC than bacterial joint infections. However, there is overlap in their presentation and clinicians should remain vigilant to always consider septic arthritis and not assume gout.
- Watch out for: history with new skincare products, detergents, with physical exam demonstrating pruritic vesicles, bullae—this could be a “simple” case of contact dermatitis
- Diagnosis is my history and exam. Treatment is avoiding of allergen and supportive care. Steroids may be indicated in refractor or extreme cases.
Always be aware of these other sneaky diagnoses—missing these might cause further problems down the road!
Back to the story…
After obtaining labs, x-ray of left wrist and elbow, and providing some pain control, ortho was consulted to obtain synovial fluid sample. Synovial fluid analysis showed crystals and less than 10,000 WBC. Smear showed no bacterial, and cultures did results as negative. Because of his atypical gout presentation with fever, redness spreading down his arm, and recent marine exposure, it was determined to also treat him for possible cellulitis with doxycycline to cover marine bacteria.
References
1. Raff AB, Kroshinsky D. Cellulitis: A Review. JAMA. 2016 Jul;316(3):325-37. https://jamanetwork.com/journals/jama/fullarticle/2533510
2. Spelman D, Baddour L . Cellulitis and skin abscess: Clinical manifestations and diagnosis. UpToDate Sep 06, 2017.
AMP EM 