Cellulitis differential diagnosis


 * Associate Editor(s)-In-Chief: Aditya Govindavarjhulla, M.B.B.S.

Overview
Cellulitis results in activation of the body's inflammatory response mechanisms. When the immune system cannot respond adequately, it can spread systemically through the blood stream.

Differential Diagnosis
Cellulitis can be promptly diagnosed with appropriate history and physical exam. Administration of antibiotic therapy will initiate resolution the condition in a 2-3 days. Differentials have to be thought of only when resolution is not seen. Non resolution can be even due to resistant strains of the bacterium involved. There are many dermatological conditions which manifest in similar manner. Careful evaluation of each case basing on history and physical is very important. Few differentials are as follows:


 * Erysipelas is a skin infection similar to Cellulitis, but affecting superficial layers of the skin. It has well demarcated edges than cellulitis.


 * Erysipeloid is a skin infection which is mostly occupational in nature. It is most commonly seen in persons in poultry and meat industry. it had local lesions, diffuse lesions and systemic forms.


 * Deep vein thrombosis, a condition in which clot is formed the veins. It can be differentiated by tenderness along the vein. Duplex ultrasonography reveals clot in the vein.


 * Necrotizing fasciitis, it looks like cellulitis at the begining but it is more serious. Very great pain ,necrosis and bullae are noticeable. It often requires surgical exploration.

There are few conditions which can be misdiagnosed as cellulitis like, thrombophlebitis, contact dermatitis, insect stings, drug reactions, arthritis.


 * Contact Dermatitis, is an inflammation of the skin in response to direct exposure to an allergic or irritant substance.They usually present with papular erythematous indistinct margins. Extent of distribution is often limited to area of exposure.
 * Insect Bites, cause a local reaction leading to erythema, tenderness, pruritus and edema. In severe reaction it can be involve adjacent joints. In very severe cases it can even lead to anaphylaxis also.
 * Drug rash, is the cutaneous form of drug reactions. It is quite variable ranging from pinkish hue to an exanthem. It can be limited or widespread. Itching is the most common symptom. If fever, dehydration and involvement of membranous surfaces is seen then other diagnosis has to be thought of. Most common drugs being Sulfa, Anticonvulsant drugs, Insulin from animal sources.