Differential Diagnosis for Dorsum Hand Redness and Swelling

Single Most Likely Diagnosis

• Cellulitis: This is a common infection of the skin and subcutaneous tissues, often caused by bacteria such as Streptococcus or Staphylococcus. Given the patient's recent hospitalization, the skin integrity might have been compromised, making it susceptible to infection. The presentation of redness and swelling on the dorsum of the hand is consistent with cellulitis.

Other Likely Diagnoses

• Phlebitis: If an IV was previously placed at the site, phlebitis (inflammation of the vein) could be a cause of the redness and swelling. This condition can occur due to irritation from the IV catheter or infusion of certain medications.
• Contact Dermatitis: An allergic reaction or irritation from a substance (such as soap, lotion, or a medical tape) could cause dermatitis, leading to redness and swelling on the dorsum of the hand.
• Insect Bite or Sting: Depending on the environment and recent activities, an insect bite or sting could cause localized redness and swelling.

Do Not Miss Diagnoses

• Necrotizing Fasciitis: Although rare, this is a life-threatening infection that requires immediate attention. It can present with severe pain, redness, and swelling, and can rapidly progress. Recent hospitalization and possible skin compromise increase the risk.
• Compartment Syndrome: This is a condition where increased pressure within a muscle compartment leads to inadequate blood supply to the tissues. It can cause pain, swelling, and pallor, and is a medical emergency.
• Deep Vein Thrombosis (DVT): While less common in the upper extremities, DVT can occur, especially in patients with risk factors such as recent hospitalization, immobility, or cancer. It presents with swelling, redness, and warmth, and can lead to pulmonary embolism if not treated.

Rare Diagnoses

• Erythema Migrans (Lyme Disease): If the patient has been exposed to ticks, erythema migrans, the rash associated with Lyme disease, could be considered. However, it typically presents as a distinctive "bull's-eye" rash.
• Sarcoidosis: A systemic disease that can cause skin lesions, including on the hands, but this would be part of a broader systemic illness.
• Vasculitis: Inflammation of the blood vessels can cause a variety of skin manifestations, including redness and swelling, but this is usually part of a systemic condition with other symptoms.