What is the diagnosis and treatment for bilateral anterior leg swelling, fever, bitter taste, weight loss, and body malaise?

Differential Diagnosis and Management Approach

This presentation of bilateral anterior leg swelling with fever, bitter taste, weight loss, and malaise requires urgent evaluation for necrotizing soft tissue infection, which is a life-threatening emergency requiring immediate surgical consultation and broad-spectrum antibiotics within 1-4 hours. 1

Immediate Life-Threatening Considerations

Necrotizing Soft Tissue Infection (Primary Concern)

• Bilateral leg swelling with fever in this context indicates rapid polymicrobial bacterial spread with potential for limb loss or life-threatening sepsis. 1
• Look specifically for: pain out of proportion to physical findings, crepitus (indicating gas-forming anaerobes), skin discoloration, or rapidly progressive erythema. 1
• If any of these features are present, obtain immediate surgical consultation for emergency debridement within 1-4 hours and start IV vancomycin PLUS piperacillin-tazobactam before surgery. 1
• Early surgery (within 24-48 hours) results in lower amputation rates compared to delayed intervention. 1

Critical Initial Assessment

• Examine for exposed bone, deep ulceration, or wounds overlying bony prominences—these suggest diabetic foot infection with possible osteomyelitis if the patient has diabetes. 2, 3
• Assess vascular status urgently with ankle-brachial index (ABI) and consider vascular imaging, as peripheral arterial disease with infection requires urgent revascularization. 1
• Check for crepitus specifically, which mandates urgent surgical exploration. 1

Secondary Differential Diagnoses

Systemic Infections with Musculoskeletal Involvement

Tickborne Rickettsial Disease (Rocky Mountain Spotted Fever)

• Fever, malaise, and bilateral leg involvement can occur with RMSF, though leg swelling is less typical. 2
• Query recent outdoor activities, tick exposure, or travel to endemic areas. 2
• Look for rash on ankles/wrists evolving to petechiae (appears 2-4 days after fever onset in 90% of children, less in adults). 2
• Headache is nearly always reported by adults and can be severe; photophobia, nausea, vomiting, and conjunctival injection are common. 2

Melioidosis

• Consider if patient has diabetes, presents with fever, malaise, and multiple abscesses. 4
• Can manifest as soft tissue abscesses, septic arthritis, or osteomyelitis affecting lower extremities. 4
• Blood cultures positive for Burkholderia pseudomallei confirm diagnosis. 4
• Treatment requires IV ceftazidime 2g every 6 hours or IV meropenem for 10-14 days, followed by 3-6 months oral co-trimoxazole. 4

Whipple's Disease

• Rare but presents with fever, weight loss, malaise, and migratory arthralgia affecting joints. 5
• Gastrointestinal symptoms (diarrhea, abdominal pain) are most common but not always present initially. 5
• Diagnosis requires small intestine biopsy showing PAS-positive macrophages. 5
• Requires extended antibiotic treatment up to 1 year. 5

Diabetic Foot Complications (If Patient Has Diabetes)

Charcot Neuro-Osteoarthropathy

• Bilateral active CNO reduces reliability of temperature difference measurements between feet. 2
• In bilateral disease, measure ascending temperature gradients (toe-to-knee) comparing distal foot to proximal leg temperatures. 2
• Knee-high immobilization/offloading should be initiated immediately when active CNO is suspected in a diabetic patient with intact skin. 2
• Use infrared thermometry or hand palpation to assess temperature differences. 2

Diabetic Foot Osteomyelitis

• Suspect if patient has diabetes with chronic ulcers, exposed bone, or "sausage toe" appearance. 3
• Perform probe-to-bone test, plain X-rays, and check inflammatory markers (ESR, CRP, PCT) as initial studies. 3
• If diagnosis remains uncertain, obtain MRI. 3
• Treatment requires 4-6 weeks of antibiotics without surgery, or 3 weeks if surgical debridement performed with positive bone margins. 3

Non-Infectious Causes

Decompensated Heart or Renal Failure

• Bilateral leg swelling with malaise and weight loss (from fluid retention) suggests cardiac or renal decompensation. 6
• Check for jugular venous distension, pulmonary edema, and obtain BNP, creatinine, and urinalysis. 6

Drug Side Effects

• Review all medications for those causing peripheral edema (calcium channel blockers, NSAIDs, corticosteroids). 6
• Drug-induced edema may be exacerbated in warm environments. 6

Venous Thrombosis

• Though typically unilateral, bilateral DVT can occur and may unmask malignant disease. 6
• Obtain D-dimer and venous duplex ultrasound if clinical suspicion exists. 6

Diagnostic Algorithm

1. Immediately assess for necrotizing infection signs (crepitus, skin discoloration, pain out of proportion). 1
2. If present: Emergency surgical consultation + IV vancomycin + piperacillin-tazobactam within 1-4 hours. 1
3. If absent: Examine for diabetic foot complications (ulcers, exposed bone, temperature asymmetry). 2, 3
4. Obtain blood cultures, inflammatory markers (ESR, CRP), complete blood count, and plain radiographs of legs. 3
5. Check vascular status with ABI and assess glycemic control if diabetic. 1
6. Query tick exposure, travel history, and gastrointestinal symptoms. 2, 5

Critical Pitfalls to Avoid

• Never delay surgery for prolonged antibiotic therapy if necrotizing infection is suspected—this increases mortality. 1
• Never rely on superficial wound swabs for culture diagnosis; obtain deep tissue or bone samples. 1
• Do not continue antibiotics until complete wound healing—stop when infection signs resolve to prevent resistance. 1
• In bilateral foot disease, do not rely solely on contralateral foot temperature comparison; use ascending gradients instead. 2