In a patient with a recent computed tomography angiography showing no acute vascular abnormality (only mild fatty liver change, residual linear atelectasis, and thin fibrotic bands in the right lower lung) who now presents with purplish linear cutaneous markings following the superficial abdominal veins extending to the flanks, right‑sided flank and abdominal pain, and new shortness of breath, what is the most appropriate next step in management?

Urgent Evaluation for Superficial Venous Thrombosis and Possible Pulmonary Embolism

This patient requires immediate lower extremity venous ultrasound to evaluate the purplish linear markings along superficial abdominal veins, followed by repeat CT pulmonary angiography (CTPA) if clinical suspicion for pulmonary embolism remains high despite the negative initial angiogram. The combination of new shortness of breath, flank/abdominal pain, and visible venous changes suggests evolving thrombotic disease that may not have been present or detectable on the initial scan 1.

Immediate Diagnostic Steps

Venous Ultrasound Evaluation

• Obtain compression venous ultrasonography of both lower extremities and the abdominal wall veins to assess for deep vein thrombosis (DVT) or superficial venous thrombosis 1.
• The purplish linear markings following superficial veins are concerning for thrombophlebitis or superficial venous thrombosis, which can extend into the deep venous system 1.
• Even when CTPA is negative, finding a proximal DVT on ultrasound justifies anticoagulation treatment 1.

Reassess for Pulmonary Embolism

• The initial negative CT angiogram does not definitively exclude PE in patients with high clinical suspicion, as the negative predictive value drops to approximately 60% in high-probability patients 2.
• New shortness of breath developing after a negative CTPA warrants repeat imaging with optimized technique or alternative modalities 2.
• Consider that the three-month thromboembolic risk after negative CTPA is 1.1%, meaning delayed or propagating clots can occur 2.

Clinical Probability Assessment

High-Risk Features Present

• This patient demonstrates multiple concerning features: new respiratory symptoms, unilateral flank pain, and visible venous abnormalities—all suggesting high clinical probability for venous thromboembolism 1.
• When clinical judgment conflicts with negative imaging, pursue additional testing rather than relying on the scan alone 2.

Alternative Imaging Considerations

• If repeat CTPA cannot be performed (contrast allergy, renal impairment), ventilation-perfusion (V/Q) scanning is the preferred alternative with lower radiation exposure 3, 2.
• V/Q scanning has a 99% negative predictive value when normal and can safely exclude PE 3.

Evaluation of Incidental Findings

Fatty Liver Assessment

• The "slight fanny liver linear" finding likely represents focal fatty infiltration or perivascular fatty changes, which are benign and commonly seen in patients with alcohol use, metabolic syndrome, or cirrhosis 4, 5.
• Perivascular fatty infiltration can surround hepatic veins or portal tracts and should not be confused with vascular or neoplastic disease 5.
• This finding does not require immediate intervention but may indicate underlying liver disease 4.

Lung Parenchymal Findings

• Linear atelectasis and thin fibrotic bands in the right lower lobe are non-acute findings that do not explain the current symptoms 1.
• However, pulmonary infarcts from PE can manifest as peripheral airspace opacities with heterogeneous enhancement, sometimes showing a reversed halo sign 1.
• Review the lung windows carefully for any subtle peripheral consolidation that might represent pulmonary infarction 1.

Critical Next Steps Algorithm

1. Immediate: Order bilateral lower extremity and abdominal wall venous ultrasound
2. If ultrasound positive for DVT: Initiate anticoagulation immediately 1
3. If ultrasound negative but high clinical suspicion persists:
   • Obtain repeat CTPA with optimized contrast timing 2
   • Or perform V/Q scanning if CTPA contraindicated 3, 2
4. Assess for signs of chronic thromboembolic disease: Look for webs, bands, mosaic perfusion, or enlarged bronchial arteries on imaging 1

Common Pitfalls to Avoid

• Do not assume a single negative CTPA excludes all venous thromboembolism, especially when clinical features evolve 2.
• Do not dismiss superficial venous changes as purely dermatologic; they may represent thrombophlebitis requiring treatment 1.
• Do not confuse perivascular fatty infiltration with vascular pathology on CT—MRI can clarify if needed 5.
• Mosaic attenuation and enlarged bronchial arteries are NOT seen with acute PE alone; their presence suggests chronic thromboembolic pulmonary vascular disease 1.