Hypervascularity in a Fatty Hilum is NOT the Concerning Type
The hypervascularity you describe—occurring within a large fatty hilum—represents benign reactive flow and is distinctly different from the concerning peripheral/cortical hypervascularity that predicts malignancy. This 27mm groin lymph node with preserved fatty hilum is reassuring despite the increased vascularity.
Why This Hypervascularity Pattern is Benign
Central hilar vascularity (single central vessel) is a benign finding, with studies demonstrating that lymph nodes with a central intranodal vessel pattern (Nakajima grade 0-1) are consistently benign 1. The presence of a fatty hilum itself is the single most important benign feature in lymph node assessment, with 96-100% specificity for excluding metastatic disease 2, 3.
When hypervascularity occurs within the fatty hilum, this represents normal or reactive vascular supply through the hilum—the natural entry/exit point for blood vessels in lymph nodes 1. This is fundamentally different from malignant hypervascularity.
The Concerning Hypervascularity Pattern You DON'T Have
Malignant hypervascularity manifests as peripheral/cortical vessels with rich flow involving >4 vessels (Nakajima grades 2-3), which carries 87.7% sensitivity and 69.6% specificity for malignancy 1. This pattern shows:
- Multiple peripheral vessels penetrating the cortex
- Disorganized vascular architecture
- Loss of central hilar structure
- Often accompanied by cortical thickening >3mm 2, 4
Your node explicitly has a preserved large fatty hilum, which is the opposite of this malignant pattern.
Additional Reassuring Features
The presence of an intact fatty hilum substantially lowers malignancy risk, with the American College of Radiology stating this has high negative predictive value for malignancy 2, 3. Even with mild cortical heterogeneity, the preserved fatty hilum remains the dominant reassuring feature 2.
Reactive lymphadenopathy from infection or inflammation commonly demonstrates increased blood flow, and the combination of hypervascularity with preserved fatty hilum favors a reactive rather than malignant process 3.
Size Considerations
At 27mm in long axis (likely ~16mm short axis based on your dimensions), this node exceeds some conservative thresholds. Lymph nodes ≤15mm in short axis consistently demonstrate reactive or benign pathology 2. However, size becomes less predictive when a fatty hilum is preserved 1.
Clinical Context Matters
In a young adult with no significant medical history and no systemic symptoms, reactive lymphadenopathy is far more likely than lymphoma 3, 5. The National Comprehensive Cancer Network recommends observation and monitoring as the standard approach for reactive lymphadenopathy 3.
When to Escalate
You should pursue biopsy if any of these develop 2, 4:
- Loss of fatty hilum on follow-up imaging (90-93% positive predictive value for malignancy)
- Progressive enlargement beyond current size
- Development of irregular borders, necrosis, or extranodal extension
- Cortical thickness exceeding 3mm
- New systemic B symptoms (fever, night sweats, weight loss)
Recommended Approach
Short-interval ultrasound follow-up in 4-6 weeks is appropriate to document stability or resolution, which would confirm the reactive nature 2, 3. If the node remains stable or decreases, no further imaging is needed. If it enlarges or develops concerning features, ultrasound-guided fine-needle aspiration has 80-93% sensitivity and approaches 100% specificity for detecting malignancy 3, 4.
Critical Distinction
The radiologist's description of "hypervascular large fatty hilum" indicates increased flow through the hilum itself—the normal vascular pathway—not the pathologic peripheral hypervascularity that characterizes malignancy 1. This is an important semantic distinction that changes the clinical significance entirely.