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--- bosniak [2026/01/13 09:34] – akestorck
+++ bosniak [2026/01/13 09:41] (aktuell) – akestorck
@@ Rad 1: / Rad 1: @@
 ====== Bosniak Classification Version 2019 ======
-**Bosniak classification version 2019** updates the 1986/2005 system for stratifying malignancy risk in cystic renal masses on CT/MRI. Key changes include MRI incorporation, precise enhancement definitions, expanded Bosniak II criteria, and reduced Bosniak III category to minimize unnecessary surgeries.
-===== Epidemiology =====
-Simple cysts (Bosniak I) in 20-40% adults >50 years. Complex cystic masses (IIF-IV) comprise 1-4% renal masses. Updated malignancy risk stratification:
-* **I/II**: 0%
-* **IIF**: ~7%
-* **III**: ~60%
-* **IV**: >90%
-===== Clinical presentation =====
-Incidental finding on imaging for unrelated conditions (90%). Symptomatic: flank pain, hematuria, palpable mass (large/advanced lesions).
-===== Pathology =====
-**Bosniak I/II**: benign simple epithelial cysts
-**Bosniak IIF**: mostly benign, low-risk complex cysts
-**Bosniak III**: indeterminate (multilocular cystic RCC, hemorrhagic cysts)
-**Bosniak IV**: cystic renal cell carcinoma (90%+ malignant)
-===== Radiographic features =====
-==== Computed Tomography / MRI (Multiphase Required) ====
-  * **Bosniak I** (benign, 0% risk)
-  * Thin wall (≤2 mm, may enhance)
-  * Simple fluid content (-9 to 20 HU)
-  * No septa, calcifications, or solid components
-  * **Bosniak II** (benign, 0% risk) - **EXPANDED**
-  * **Six subtypes**:
-    * Thin septa (≤2 mm, 1-3, may enhance ± calcification)
-    * Mildly thickened wall/septa (~3 mm perceived thickness)
-    * Homogeneously hyperattenuating (70+ HU, non-enhancing)
-    * Homogeneous >20 HU cysts (non-enhancing)
-    * Too small to characterize (<15 mm, homogeneous)
-    * Complete cortical rim of fat
-  * **Bosniak IIF** (follow-up, ~7% risk)
-  * Wall/septa >3 mm and <4 mm (smooth, measurable enhancement)
-  * ≥4 septa (≤2 mm thick, may enhance)
-  * **Bosniak III** (surgery, ~60% risk) - **REDUCED**
-  * Thick (≥4 mm) or irregular enhancing walls/septa
-  * **No non-enhancing thick/irregular walls** (now II/IIF)
-  * **Bosniak IV** (malignant, >90% risk)
-  * Enhancing soft-tissue nodule (≥4 mm)
-  * **Any size nodule with acute margins**
-  * **Enhancement definition**: ≥20 HU (CT) or visually perceived/measurable (MRI)
-==== Ultrasonography ====
-Screening only. Cannot assess enhancement or precise measurements. Simple cysts: anechoic, thin walls, posterior enhancement.
-===== Treatment and prognosis =====
-* **I/II**: no follow-up
-* **IIF**: surveillance CT/MRI (6, 12, 24 months)
-* **III**: surgical resection
-* **IV**: nephron-sparing surgery/ablation
-Reduces unnecessary surgeries by 20-30% vs original classification.
-===== Differential diagnosis =====
-  * **Abscess**: clinical fever, wall enhancement
-  * **Hydatid cyst**: daughter cysts, eccentric wall calcification
-  * **Hemorrhagic cyst**: evolves on follow-up
-  * **Lymphangioma**: multiple septations
-  * **Metastases**: multiple lesions
-===== References =====
-* [[https://pubs.rsna.org/doi/full/10.1148/radiol.2019182646|Radiology 2019: Bosniak v2019]]
-* [[https://pubs.rsna.org/doi/full/10.1148/rg.2021200160|RadioGraphics 2021: Pictorial Guide]]
-* [[https://radiologyassistant.nl/abdomen/kidney/bozniak-2019|Radiology Assistant: Bosniak 2019]]
-> **Medical Disclaimer**: Portions of this content were AI-generated to facilitate rapid knowledge synthesis. Radiologists and clinicians must independently verify all information against peer-reviewed literature, institutional protocols, and patient-specific factors before clinical application.