Differential Diagnosis
The patient presents with bilateral lower extremity swelling, redness, and itching, which can be caused by a variety of conditions. Given the patient's complex medical history and laboratory results, the differential diagnosis can be categorized as follows:
- Single Most Likely Diagnosis
- Cellulitis: The patient's symptoms of bilateral lower extremity swelling, redness, and itching, along with a elevated WBC count (11.9) and CRP (9.081), are consistent with cellulitis. The absence of DVT on venous duplex also supports this diagnosis.
- Other Likely Diagnoses
- Chronic Venous Insufficiency: The patient's symptoms of lower extremity swelling and redness could be related to chronic venous insufficiency, especially given the patient's history of obesity and ambulatory status with a walker.
- Stasis Dermatitis: The patient's symptoms of itching and redness could be related to stasis dermatitis, which is a common condition in elderly patients with chronic venous insufficiency.
- Contact Dermatitis: The patient's symptoms of itching and redness could be related to contact dermatitis, which could be caused by an allergic reaction to a substance in contact with the skin.
- Do Not Miss Diagnoses
- Necrotizing Fasciitis: Although less likely, necrotizing fasciitis is a life-threatening condition that requires prompt diagnosis and treatment. The patient's severe pain and elevated WBC count warrant consideration of this diagnosis.
- Gas Gangrene: Similar to necrotizing fasciitis, gas gangrene is a life-threatening condition that requires prompt diagnosis and treatment. The patient's severe pain and elevated WBC count warrant consideration of this diagnosis.
- Rare Diagnoses
- Erythema Nodosum: The patient's symptoms of redness and swelling could be related to erythema nodosum, which is a rare condition characterized by inflammation of the subcutaneous fat.
- Lymphedema: The patient's symptoms of lower extremity swelling could be related to lymphedema, which is a rare condition characterized by abnormal lymphatic drainage.
Workup and Management
The patient's workup should include:
- Complete blood count (CBC) with differential to evaluate for signs of infection or inflammation
- Blood cultures to evaluate for bacteremia
- Wound culture to evaluate for bacterial infection
- Imaging studies, such as MRI or CT scan, to evaluate for underlying conditions such as abscess or necrotizing fasciitis
- Consideration of biopsy to evaluate for underlying conditions such as necrotizing fasciitis or gas gangrene
Management should include:
- Antibiotics to treat bacterial infection
- Pain management to control severe pain
- Wound care to promote healing and prevent infection
- Consideration of surgical intervention to treat underlying conditions such as abscess or necrotizing fasciitis
Imaging Studies
Given the patient's chronic kidney insufficiency, the use of CT scan with IV contrast should be carefully considered. While CT scan with IV contrast can provide valuable information, it also carries a risk of contrast-induced nephropathy. MRI without contrast is an alternative option that can provide valuable information without the risk of contrast-induced nephropathy. However, MRI may not be as sensitive as CT scan for certain conditions, such as abscess or necrotizing fasciitis.
In this case, the benefits of CT scan with IV contrast may outweigh the risks, especially if the patient's symptoms suggest a life-threatening condition such as necrotizing fasciitis or gas gangrene. However, the decision to use CT scan with IV contrast should be made in consultation with a radiologist and nephrologist, and alternative imaging studies such as MRI without contrast should be considered.