Can Bone Infarct Occur with Cellulitis?
Yes, bone infarcts can occur concurrently with cellulitis, particularly in patients with sickle cell disease, where bone infarction may clinically mimic or coexist with infectious processes including cellulitis, osteomyelitis, and soft tissue infections.
Clinical Overlap in Sickle Cell Disease
The relationship between bone infarcts and cellulitis is most clinically relevant in patients with sickle cell disease, where these conditions frequently present diagnostic challenges:
Bone infarcts in sickle cell disease commonly mimic infectious processes, including cellulitis, abscess formation, and osteomyelitis, making clinical differentiation extremely difficult 1.
Facial bone infarctions specifically can present with swelling and erythema that closely resembles cellulitis or pre-septal cellulitis, as demonstrated in pediatric cases where orbital bone infarction was initially misdiagnosed as periorbital cellulitis 2.
The clinical presentation of bone infarction includes localized pain, swelling, warmth, and erythema—symptoms that overlap substantially with cellulitis 1, 3.
Pathophysiology of Concurrent Presentation
Acute bone infarcts in sickle cell disease result from sequestration of red blood cells in bone marrow, causing regional hypoxia and subsequent tissue damage 3.
Soft-tissue lesions associated with bone infarcts can develop adjacent to the infarcted bone, creating a clinical picture that includes both bone pathology and overlying soft tissue inflammation 3.
The mandible and orbital bones are most commonly affected when facial bone infarctions occur, and these locations frequently present with overlying soft tissue swelling that mimics cellulitis 1.
Diagnostic Differentiation
Imaging Approach
Sequential bone marrow and bone scans performed within 24 hours can differentiate bone infarction from osteomyelitis: bone infarction shows decreased uptake on bone marrow scan with abnormal uptake on bone scan, while osteomyelitis shows normal uptake on bone marrow scan with abnormal uptake on bone scan 4.
MRI with T1 fat-saturated sequences is diagnostic for acute bone infarcts, showing signal intensity ratios of 1.7±0.5 compared to skeletal muscle, versus 1.0±0.3 for osteomyelitis (p=0.003) 3.
Timing of imaging is critical: bone scans performed ≤3 days after symptom onset show no increased uptake in infarction, while scans performed ≥7 days show increased uptake that may be indistinguishable from osteomyelitis 5.
Clinical Distinction
Pure cellulitis without bone involvement shows normal bone scans and bone marrow scans, helping exclude underlying bone pathology 5.
Patients with cellulitis alone do not have the deep bone pain characteristic of bone infarction, though overlying soft tissue inflammation from bone infarct can mimic cellulitis 1.
Management Implications
When Bone Infarct is Suspected in Sickle Cell Patients
Discontinue empirical antibiotics if imaging confirms bone infarction without osteomyelitis—in 66 of 70 cases of confirmed bone infarction, antibiotics were safely discontinued after imaging, and bone pain resolved with supportive care alone 4.
Supportive treatment for vaso-occlusive crisis is the primary management for bone infarction, not antibiotics 2.
Image-guided aspiration should be considered when osteomyelitis cannot be excluded by imaging alone, particularly if empirical antibiotics are being considered 3.
Critical Pitfall to Avoid
Do not assume all soft tissue swelling and erythema in sickle cell patients represents infection requiring antibiotics—bone infarction with overlying soft tissue inflammation is far more common than osteomyelitis (70 cases of infarction versus 4 cases of osteomyelitis in one series) 4.
Avoid prolonged empirical antibiotic therapy without definitive imaging in sickle cell patients with bone pain and overlying soft tissue changes, as this represents overtreatment in the majority of cases 3, 4.
Clinical Algorithm for Sickle Cell Patients with Suspected Cellulitis
Assess for underlying bone pain: if present, consider bone infarction as primary diagnosis rather than isolated cellulitis 1, 2.
Obtain MRI with T1 fat-saturated sequences within 24-48 hours if bone involvement is suspected—this single sequence can be diagnostic for bone infarction without contrast 3.
If imaging shows bone infarction pattern (high T1 signal intensity ratio >1.5 compared to muscle), discontinue antibiotics and treat as vaso-occlusive crisis 3, 4.
If imaging shows osteomyelitis pattern (normal bone marrow scan uptake with abnormal bone scan uptake, or low T1 signal intensity ratio ~1.0), continue antibiotics and consider image-guided aspiration for culture 3, 4.
If imaging is normal, cellulitis may be the primary diagnosis and should be treated according to standard cellulitis guidelines with beta-lactam monotherapy for 5 days 6, 5.