Which cancer type is most likely to cause hemorrhagic metastases in a patient with multiple small areas of signal loss on MRI susceptibility-weighted imaging (SWI)?

Renal Cell Carcinoma is Most Likely to Cause These Hemorrhagic Brain Metastases

Renal cell carcinoma (RCC) carries the highest propensity for causing hemorrhagic brain metastases among the options provided, particularly when multiple small lesions with signal loss on susceptibility-weighted imaging (SWI) are present. 1

Primary Cancers Associated with Hemorrhagic Brain Metastases

The Society for Neuro-Oncology identifies specific primary cancers with high propensity for intracranial hemorrhage 1:

• Melanoma - Most hemorrhagic overall
• Renal cell carcinoma - Second most hemorrhagic
• Thyroid carcinoma - Moderate hemorrhagic tendency
• Ovarian cancer - Moderate hemorrhagic tendency
• Choriocarcinoma - High hemorrhagic tendency (not listed in options)

Among the answer choices provided, renal cell carcinoma is the most likely culprit 1.

Why Renal Cell Carcinoma is the Answer

Characteristic Hemorrhagic Features

• RCC metastases demonstrate hyperintensity on T1- and T2-weighted images with loss of signal on T2- or susceptibility-weighted imaging*, the exact pattern described in this case 1
• The metastatic tumor from RCC has a propensity for intratumoral hemorrhage compared with other metastatic tumors 2
• SWI is 100% sensitive for detecting hemorrhage in RCC lesions, making it the ideal sequence for identifying these lesions 3

Pattern Recognition on MRI

• Multiple small areas with signal loss on SWI represent hemosiderin deposition from prior hemorrhage, creating susceptibility artifact 1
• RCC brain metastases characteristically show relatively massive surrounding edema compared to other metastatic tumors 2
• The subcortical gray-white junction location is typical for hematogenous metastases 1

Why Other Options Are Less Likely

Lung Adenocarcinoma

• While lung cancer is the most common source of brain metastases overall, it does not have the same hemorrhagic propensity as RCC 1
• Hemorrhagic metastases from lung cancer are less frequent and typically less dramatic 4

Breast Adenocarcinoma

• Breast metastases can be hyperenhancing on arterial phase imaging, but only 10-26% show this pattern 1
• Hemorrhagic breast metastases are uncommon compared to RCC 1

Multiple Myeloma

• Multiple myeloma rarely metastasizes to the brain parenchyma
• When CNS involvement occurs, it typically affects the dura or leptomeninges, not brain parenchyma

Squamous Cell Carcinoma

• Squamous cell carcinomas (typically from lung, head/neck) do not have characteristic hemorrhagic propensity 1
• These metastases are generally non-hemorrhagic

Clinical Implications

Diagnostic Workup

• Obtain contrast-enhanced CT chest/abdomen/pelvis to identify the primary renal mass 2
• Consider abdominal MRI with and without contrast if CT is equivocal, as RCC shows characteristic enhancement patterns 1
• The presence of hemorrhagic brain metastases should prompt evaluation for RCC even without known primary 2

Management Considerations

• RCC brain metastases are relatively radioresistant to conventional whole brain radiotherapy 2
• Stereotactic radiosurgery (SRS) shows excellent outcomes for tumor control and surrounding edema management 2
• Surgical resection may be indicated for symptomatic hemorrhagic lesions, particularly solitary metastases 2, 4

Critical Pitfall to Avoid

Do not assume lung cancer simply because it is the most common source of brain metastases overall. The hemorrhagic nature on SWI is the key distinguishing feature that points specifically to RCC (or melanoma, which is not among the choices) 1. The pattern of multiple small hemorrhagic foci with susceptibility artifact is pathognomonic for tumors with high vascularity and propensity for bleeding 1, 3.