The patient has lymphangitic streaking, indicating spread of the skin and soft tissue infection into his lymphatic system. Many practitioners would admit all patients with presumed bacterial lymphangitis for IV antibiotics. However, if a child is > 3 years old, well-appearing, afebrile, and the family is reliable, a trial of outpatient management with antibiotics that cover Staph aureus and Group A beta-hemolytic Strep, the most common causes, is reasonable. This patient was admitted due to failure of outpatient management.

In the differential diagnosis would be sporotrichosis, a fungal infection caused by an organism found in soil and on plant matter, Sporothrix schenckii. The organism may be inoculated into the skin via a scratch (eg from a rose thorn) or animal bite (especially cats). A papule or nodule forms at the site of inoculation 1-10 weeks after inoculation. It becomes pustular and then ulcerative, and may then ascend lymphatic channels.