Kidney Fx Cyst Septated 5.2cms Dx Bosniak IIF (CT)

5.2cms Cyst in the Right Kidneylesion

1. Findings


Septated Renal Cyst on CT 5.2cms
CT through the mid abdomen in axial projection shows a lobular cyst with fine septations in the mid portion of the right kidney.
Ashley Davidoff MD TheCommonVein.net 130769
Bosniak Category Imaging Features Malignancy Risk Management
I – Simple cyst
– Thin wall, no septa, calcifications, or solid components
Water attenuation (<20 HU)
No enhancement
~0% Benign → No follow-up needed
II – Minimally complex
– Few thin septa
– Fine or thin calcifications
No measurable enhancement
– May include hyperdense cysts <5 cm (if well-marginated and non-enhancing)
~0% Benign → No follow-up needed
IIF – Multiple thin septa
– Possible minimal smooth thickening
– May have minimal enhancement
– May contain calcification, or be hyperdense >3 cm
No solid enhancing component
~5% Probably benign → Follow-up imaging recommended
III – Thickened or irregular walls or septa
Measurable enhancement present
– No obvious solid component
~50% Indeterminate → Surgical excision or biopsy may be warranted
IV – Features of Category III plus:
Enhancing soft tissue component (nodule)
– Irregular or thick enhancement
~85–100% High risk → Surgical excision recommended

🧠 Key Terms Explained

  • Enhancement = measurable increase in HU (>10–15 HU) after contrast → indicates vascularity (suspicious)

  • Hyperdense cyst = high attenuation (40–90 HU) on non-contrast CT

  • Septations = thin internal walls; suspicious if thickened or enhancing

  • Solid components = most concerning for malignancy, especially if enhancing