||Erysipelas is an acute, localized but spreading, superficial cellulitis usually caused by Group A beta hemolytic streptococci and characterized by involvement of the lymphatics. The skin lesions are bright red, well demarcated and tender, with an elevated and distinct margin peripherally advancing.
Significant constitutional symptoms such as fever, chills, headaches, and weakness may be experienced. The infection usually begins by inoculation of streptococci through a fissure or other break in the skin. Histologically, erysipelas is characterized by marked edema, with dilatation of the capillaries and lymphatics, and with a diffuse infiltration of neutrophils. With Gram's stain, streptococci will be seen within the lymphatics and scattered throughout the tissue.
In this patient the cellulitis which originated on the pinna has extended anteriorly across the cheek. The advancing margin can be clearly seen.