Differential Diagnosis
The patient presents with bilateral lower extremity swelling, redness, and itching, which can be caused by a variety of conditions. Here is a differential diagnosis, categorized for clarity:
- Single Most Likely Diagnosis
- Cellulitis: Given the patient's symptoms of bilateral lower extremity swelling, redness, and itching, along with a elevated WBC count (11.9) and CRP (9.081), cellulitis is a strong consideration. The absence of a DVT on venous duplex also points away from thrombotic causes, making cellulitis more likely.
- Other Likely Diagnoses
- Chronic Venous Insufficiency (CVI): The patient's symptoms of lower extremity swelling and redness could be indicative of CVI, especially given her age and mobility issues. CVI can cause skin changes and swelling due to poor circulation.
- Stasis Dermatitis: This condition is characterized by skin inflammation and irritation due to fluid buildup, which could explain the patient's itching and redness. It's often seen in patients with poor circulation or mobility issues.
- Contact Dermatitis: Although less likely given the bilateral nature of the symptoms, contact dermatitis could be a consideration if the patient has been exposed to an allergen or irritant that affects both legs.
- Do Not Miss Diagnoses
- Necrotizing Fasciitis: Although rare, this condition is life-threatening and requires immediate attention. The presence of severe pain, redness, and swelling, along with systemic signs of infection (elevated WBC and CRP), makes it essential to consider this diagnosis.
- Gas Gangrene: Similar to necrotizing fasciitis, gas gangrene is a rare but deadly condition that requires prompt diagnosis and treatment. The patient's symptoms of severe pain and swelling, combined with a history of poor circulation, make it crucial to rule out this condition.
- Rare Diagnoses
- Erythema Ab Igne: A rare condition caused by prolonged heat exposure, leading to skin inflammation and discoloration. Although unlikely, it could be considered if the patient has a history of using heating pads or other heat sources on her legs.
- Lymphedema: While not entirely rare, lymphedema is less likely given the acute presentation of the patient's symptoms. However, it could be a consideration if the patient has a history of cancer or lymph node removal.
Workup and Management
The patient's workup has already included a venous duplex, which ruled out DVT. Further workup may include:
- Blood cultures to rule out bacteremia
- Wound cultures if any open sores or wounds are present
- Imaging studies (e.g., MRI or CT) to evaluate for necrotizing fasciitis or gas gangrene if suspected
- Consultation with a dermatologist or wound care specialist for further evaluation and management
Management will depend on the underlying diagnosis but may include:
- Antibiotics for cellulitis or other bacterial infections
- Wound care and dressing changes for any open sores or wounds
- Elevation and compression of the affected limbs to reduce swelling
- Pain management with analgesics
- Consideration of diuretics or other medications to manage fluid overload in patients with heart failure or chronic kidney disease.