Add comprehensive documentation for adrenal conditions

- Created detailed articles for Adrenal Adenoma, Adrenal Cyst, Adrenal Myelolipoma, and general Adrenal anatomy. - Included key facts, imaging findings, differential diagnoses, pathology, clinical issues, and diagnostic checklists for each condition. - Enhanced understanding of adrenal tumors and their characteristics through structured documentation.
2025-10-17 22:27:59 +01:00
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+---
+title: "Adrenal Cyst"
+docid: "c5d717a3-3d6e-4e86-9efe-1ad0ec14740f"
+breadcrumbs:
+  - "Genitourinary"
+  - "Diagnosis"
+  - "Adrenal"
+  - "Benign Neoplasms"
+  - "Adrenal Cyst"
+---
+# KEY FACTS
+
+- ## Imaging
+  
+  
+    - "Adrenal cyst" is descriptive term, not pathological diagnosis
+    - True adrenal cysts 
+          - Majority are endothelial cysts (lymphangiomas)
+          - Epithelial cysts exceedingly rare
+          - Simple, or minimally complex, adrenal cyst, thin rim calcification, no enhancement
+    - Pseudocysts
+          - Prior hemorrhage inferred
+          - Nonenhancing but complex contents and wall calcification
+          - Relevant history (extraadrenal malignancy, rapid growth), biochemical evaluation (cortisol, metanephrines): Consider underlying adrenal neoplasm
+                  - Enhancing soft tissue components may suggest adrenal mass hemorrhage and pseudocyst formation
+    - Parasitic (echinococcal) cyst
+          - Rare outside endemic areas
+          - Typically in setting of generalized echinococcus
+- ## Top Differential Diagnoses
+  
+  
+    - Adrenal adenoma
+          - CECT: Enhancing mass without visible wall or peripheral calcifications
+    - Gastric diverticulum
+          - Air-, fluid-, or contrast-filled mass with no enhancement of contents
+    - Adrenal myelolipoma
+          - Macroscopic fat
+    - Necrotic adrenal tumor
+          - Complex wall with heterogeneous contents
+    - Retroperitoneal bronchogenic cyst
+- ## Clinical Issues
+  
+  
+    - No treatment required usually
+    - Imaging surveillance performed, although intensity and length of follow-up not defined
+    - Biochemical evaluation (cortisol, metanephrines) routinely performed to exclude underlying adrenal neoplasm
+    - Surgical resection for complex cyst with enhancing components, or symptomatic cyst
+- ## Diagnostic Checklist
+  
+  
+    - Complicated cyst has high attenuation, thick enhancing wall, &/or septations
+
+# TERMINOLOGY
+
+- ## Definitions
+  
+  
+    - "Adrenal cyst" is descriptive term, not pathological diagnosis
+          - Can mean true cyst, pseudocyst, or cystic mass
+
+# IMAGING
+
+- ## General Features
+  
+  
+    - ### Best diagnostic clue
+      
+      
+          - Well-defined, nonenhancing, water-density adrenal mass ± calcifications
+    - ### Location
+      
+      
+          - Suprarenal
+          - Unilateral > bilateral (8-10% of cases)
+    - ### Size
+      
+      
+          - < 5 cm (50%), up to 20 cm
+- ## CT Findings
+  
+  
+    - ### NECT
+      
+      
+          - Unilocular or multilocular mass
+          - Well-defined, round to oval, homogeneous mass usually with water (0 HU) or near-water density
+                  - Higher- or mixed-attenuation mass (hemorrhage, intracystic debris, crystals)
+          - Wall usually very thin
+                  - ↑ wall thickness, up to 3 mm for complex cysts
+          - Calcifications
+                  - Rim-like or nodular (51-69%)
+                  - Centrally in intracystic septation (19%)
+                  - Punctate within intracystic hemorrhage (5%)
+    - ### CECT
+      
+      
+          - No central enhancement ± wall enhancement
+          - Coronal reformats helpful to determine organ of origin if large cyst
+- ## MR Findings
+  
+  
+    - ### T1WI
+      
+      
+          - Homogeneous, hypointense mass
+          - Hyperintense mass (hemorrhage)
+    - ### T2WI
+      
+      
+          - Hyperintense mass
+- ## Ultrasonographic Findings
+  
+  
+    - Simple or septated suprarenal cyst
+    - Shadowing from calcification
+    - Real-time examination helpful to differentiate adrenal cyst from adjacent (renal, pancreatic) cyst
+- ## Imaging Recommendations
+  
+  
+    - ### Best imaging tool
+      
+      
+          - CECT or MR; US for confirmation
+
+# DIFFERENTIAL DIAGNOSIS
+
+- [Adrenal Adenoma](/document/adrenal-adenoma/e2916d86-5f9f-4dd3-9576-1a7b89d8dda0)
+    - NECT: Lipid-rich adenoma (< 10 HU) mimics adrenal cyst
+          - Peripheral or septal calcification favors adrenal cyst
+    - CECT: **Enhancing mass** without visible wall or peripheral calcifications
+          - Assess washout kinetics to diagnose lipid-poor adenoma
+    - MR: Signal suppression at out-of-phase, chemical-shift imaging
+    - US: Solid adrenal lesion
+- [Gastric Diverticulum](/document/gastric-diverticulum/eeb101f0-8bdf-4771-b44a-fe6e73b3a463)
+    - May simulate left adrenal cyst
+    - Air-, fluid-, or contrast-filled suprarenal mass
+    - No enhancement
+    - Normal adjacent adrenal gland
+- [Adrenal Myelolipoma](/document/adrenal-myelolipoma/5813a554-06a4-4696-af71-7ce50693039d)
+    - Fat (not fluid) attenuation mass
+- ## Necrotic Adrenal Tumor
+  
+  
+    - Primary (pheochromocytoma or carcinoma) or metastatic
+          - Clinical history, biochemical evaluation, lesion complexity suggest correct diagnosis
+          - Enhancing soft tissue components
+- ## Retroperitoneal Bronchogenic Cyst
+  
+  
+    - Rare, benign, suprarenal fluid or soft tissue attenuation lesion
+    - Adjacent to but separate from adrenal gland
+- ## Renal Cyst
+  
+  
+    - Coronal MR/CT or US useful to determine organ of origin of large, retroperitoneal cystic lesions
+
+# PATHOLOGY
+
+- ## General Features
+  
+  
+    - ### Etiology
+      
+      
+          - Congenital (endothelial, epithelial) cysts
+          - Acquired (post hemorrhagic, inflammatory) pseudocysts
+          - Cystic, hemorrhagic degeneration of underlying adrenal neoplasm
+- ## Staging, Grading, & Classification
+  
+  
+    - Accepted classification scheme
+          - Pseudocyst
+                  - Most common type of cystic adrenal lesion in surgical series
+                  - No epithelial or endothelial lining: Fibrous cyst wall
+                  - Potentially as complication of prior trauma or hemorrhage though history of such often not elicited
+                  - May be associated with underlying adrenal neoplasm (pheochromocytoma, adrenal carcinoma, myelolipoma)
+                  - Attenuation and complexity at imaging varies depending upon hemorrhagic component
+                  - Wall and septal calcification common
+          - Endothelial cyst
+                  - Subtypes: Lymphangiomatous and hemangiomatous
+                  - True cyst: Endothelial lining
+                  - Originate from preexisting vascular malformation or obstructed, ectatic lymphatic channels
+                  - Thin rim calcification typical
+          - Epithelial cyst
+                  - Extremely rare: No acinar structures within normal adrenal gland
+                  - Mesothelial origin suggested (mesothelial cells potentially incorporated within adrenal gland during embryogenesis)
+          - Parasitic (hydatid) cyst
+
+# CLINICAL ISSUES
+
+- ## Presentation
+  
+  
+    - ### Most common signs/symptoms
+      
+      
+          - Typically asymptomatic
+          - Larger cysts may be symptomatic
+                  - Abdominal pain
+                  - Hemorrhage
+          - Clinical history (malignancy, hypertension) elicited
+                  - May indicate cystic degeneration of underlying adrenal neoplasm (e.g., metastasis, pheochromocytoma)
+    - Diagnosis
+          - Usually incidental finding at imaging
+          - Endocrine-biochemical evaluation performed to exclude underlying functional adrenal tumor
+- ## Demographics
+  
+  
+    - ### Age
+      
+      
+          - Any, though patients 20-50 years of age most common
+    - ### Sex
+      
+      
+          - M:F = 1:3
+    - ### Epidemiology
+      
+      
+          - Uncommon entity: Autopsy incidence 0.064-0.18%
+          - Accounts for 1% of incidental adrenal lesions in large imaging series
+- ## Natural History & Prognosis
+  
+  
+    - Complications
+          - Hypertension, infection, rupture, hemorrhage
+    - Excellent prognosis for vast majority of incidental, benign adrenal cysts
+    - Prognosis for pseudocysts secondary to adrenal neoplasm depends upon tumor histology
+- ## Treatment
+  
+  
+    - No treatment required usually
+          - Imaging follow-up typically performed
+                  - Intensity and length of surveillance not defined
+          - Cysts may enlarge over time
+          - Endocrine evaluation (cortisol, metanephrine, etc.) performed
+    - Surgical resection if symptomatic, underlying adrenal neoplasm
+          - Laparoscopic resection preferred
+
+# DIAGNOSTIC CHECKLIST
+
+- ## Consider
+  
+  
+    - Complicated cyst may suggest underlying adrenal neoplasm
+    - Clinical history, biochemical evaluation, and prior imaging helpful
+- ## Image Interpretation Pearls
+  
+  
+    - Simple adrenal cyst: Scant septation, no enhancement, thin rim calcification
+          - Likely benign endothelial cyst or pseudocyst
+    - Coronal imaging helpful to determine organ of origin (and exclude exophytic renal or pancreatic cyst)
+    - Complicated cyst: High attenuation, thick enhancing wall, &/or septations
+          - Complexity may suggest underlying adrenal neoplasm and secondary pseudocyst
+
+ 35fa0290-3451-422f-8726-c69b68aadbb5