BACKGROUND: Cellulitis has many clinical mimickers (pseudocellulitis), which 
leads to frequent misdiagnosis.
OBJECTIVE: To create a model for predicting the likelihood of lower extremity 
cellulitis.
METHODS: A cross-sectional review was performed of all patients admitted with a 
diagnosis of lower extremity cellulitis through the emergency department at a 
large hospital between 2010 and 2012. Patients discharged with diagnosis of 
cellulitis were categorized as having cellulitis, while those given an 
alternative diagnosis were considered to have pseudocellulitis. Bivariate 
associations between predictor variables and final diagnosis were assessed to 
develop a 4-variable model.
RESULTS: In total, 79 (30.5%) of 259 patients were misdiagnosed with lower 
extremity cellulitis. Of the variables associated with true cellulitis, the 4 in 
the final model were asymmetry (unilateral involvement), leukocytosis (white 
blood cell count ≥10,000/uL), tachycardia (heart rate ≥90 bpm), and age 
≥70 years. We converted these variables into a points system to create the 
ALT-70 cellulitis score as follows: Asymmetry (3 points), Leukocytosis (1 
point), Tachycardia (1 point), and age ≥70 (2 points). With this score, 0-2 
points indicate ≥83.3% likelihood of pseudocellulitis, and ≥5 points indicate 
≥82.2% likelihood of true cellulitis.
LIMITATIONS: Prospective validation of this model is needed before widespread 
clinical use.
CONCLUSION: Asymmetry, leukocytosis, tachycardia, and age ≥70 are predictive of 
lower extremity cellulitis. This model might facilitate more accurate diagnosis 
and improve patient care.