Can lymphomas that preserve the fatty hilum, such as follicular lymphoma or Hodgkin lymphoma, present with a hypervascular and mildly heterogeneous cortex in a young adult with a recently developed lymph node?

Lymphoma with Preserved Fatty Hilum: Early Presentation Characteristics

Yes, follicular lymphoma and certain other lymphomas can preserve the fatty hilum in early stages, and the imaging features you describe—hypervascular node with mildly heterogeneous cortex and preserved hilum in a recently developed lymph node—do not exclude lymphoma and warrant tissue diagnosis.

Lymphomas Known to Preserve Fatty Hilum Early

Follicular Lymphoma

• Follicular lymphoma can maintain normal nodal architecture including fatty hilum preservation in early stages, making it a critical diagnostic pitfall 1
• The natural course is highly variable with spontaneous regressions occurring in 10-20% of cases, creating misleading clinical presentations 2
• Vascular patterns in lymphomatous nodes vary widely and may resemble reactive nodes in up to 50% of cases 3

Other Lymphomas with Variable Presentation

• Peripheral T-cell lymphomas of follicular helper T-cell type frequently mimic reactive hyperplasia with preserved nodal architecture 4
• Hodgkin lymphoma can present with preserved fatty hilum, particularly in young adults who are in the bimodal age distribution for this disease 5
• Angioimmunoblastic T-cell lymphoma is strongly associated with hemophagocytic lymphohistiocytosis and can have atypical presentations 2

Critical Analysis of Your Imaging Features

Preserved Fatty Hilum

• While fatty hilum has 86-93% sensitivity and 96-100% specificity for excluding metastatic disease, this applies primarily to metastatic carcinoma, not lymphoma 1
• Up to 25% of clinically negative lymph nodes harbor micrometastases, meaning imaging features alone cannot definitively exclude malignancy 1
• Reactive lymph nodes from vaccination can show hypermetabolic activity with preserved fatty hilum, but your patient's 2-week timeline makes recent vaccination less likely unless specifically queried 6

Hypervascularity

• Hypervascularity is non-specific and occurs in both reactive and lymphomatous nodes 3
• During primary immune response, significant capillary redistribution and increased density of subcapsular and medullary cord capillaries occur, peaking at day 5 7
• Lymphomatous nodes demonstrate vascular patterns in 50% of cases that are indistinguishable from reactive nodes (longitudinal vessel with branches or short vessel segments in hilum) 3

Mildly Heterogeneous Cortex

• Cortical thickness >3 mm is a red flag for malignancy 8
• Heterogeneous cortex can represent early lymphomatous infiltration before complete architectural effacement 1

Mandatory Diagnostic Algorithm

Immediate Actions Required

1. Obtain detailed history focusing on:

   • B symptoms (fever >38°C, drenching night sweats, >10% weight loss in 6 months) 5
   • Recent vaccination history, particularly COVID-19 vaccine in past 2 weeks 6
   • Upper respiratory infections or dental/oropharyngeal inflammatory processes 8
   • Family history of consanguinity, hemophagocytic lymphohistiocytosis, or lymphoproliferative disorders 2

2. Perform ultrasound-guided fine-needle aspiration biopsy (US-FNAB) as first-line diagnostic method with 80-93% sensitivity and approaching 100% specificity 1

3. If US-FNAB is non-diagnostic, proceed immediately to core needle biopsy or excisional biopsy 1

Short-Term Follow-Up Only If:

• Size <15 mm in short axis 1, 8
• Oval morphology with preserved fatty hilum 1
• No B symptoms present 5
• Clear reactive etiology identified (recent infection, vaccination) 8, 6

If observation chosen, repeat ultrasound in 4-6 weeks is mandatory 1

Red Flags Mandating Immediate Biopsy

• Progressive enlargement to >15 mm in short axis 1, 8
• Loss of fatty hilum on serial imaging 1, 8
• Development of irregular borders, necrosis, or extranodal extension 1, 8
• Cortical thickness >3 mm 8
• Persistent B symptoms 5
• Any persistence beyond 6-8 weeks without clear reactive cause 1

Critical Pitfalls to Avoid

Most Dangerous Error

The most dangerous error is assuming benignity based on reassuring imaging features alone, particularly when lymphoma can present identically to reactive nodes in early stages 1

Specific Considerations for Your Case

• The 2-week duration does not exclude lymphoma—aggressive lymphomas can present acutely, and early-stage follicular lymphoma may have preserved nodal architecture initially 1
• Hypervascularity without specific flow pattern is non-specific and occurs in 50% of lymphomatous nodes with patterns mimicking reactive nodes 3
• Mildly heterogeneous cortex may represent early lymphomatous infiltration before complete architectural destruction 1

Groin Location Specificity

• Any suspicious groin mass, regardless of fatty hilum preservation, requires diagnostic evaluation including US-FNAB, core needle biopsy, and excisional biopsy if necessary 1
• Reactive nodes are common in the groin, but lymphoma can present identically in early stages 1

Tissue Diagnosis Requirements

Excisional Biopsy Preferred

• Diagnosis should be based on surgical specimen/excisional lymph node biopsy whenever possible 2
• Core biopsies acceptable only when easily accessible lymph nodes unavailable, but heterogeneity of follicular lymphoma grading difficult to appreciate on core biopsies 2
• Fine needle aspirations are inappropriate for reliable lymphoma diagnosis 2

Pathology Requirements

• Grading according to WHO classification with blasts/high-power field count 2
• Immunohistochemistry including CD20, CD10, bcl-2, bcl-6, Ki67 2
• Consider flow cytometry for aberrant CD3(-/dim)CD4(+) T-cell population if T-cell lymphoma suspected 4
• Store fresh frozen tissue for molecular analyses including t(14;18) detection 2, 9