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.
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+---
+title: "Adrenal"
+docid: "082ca43c-db5c-4770-aeed-0c6ea317e8fc"
+breadcrumbs:
+  - "Genitourinary"
+  - "Anatomy"
+  - "Adrenal"
+---
+# TERMINOLOGY
+
+- ## Abbreviations
+  
+  
+    - Adrenal corticotrophic hormone (ACTH)
+
+# GROSS ANATOMY
+
+- ## Overview
+  
+  
+    - Adrenal (**suprarenal**) glands are part of endocrine and neurological systems
+          - Essentially different organs within same structure, composed of thick outer cortex and thin inner medulla
+          - Lie within**perirenal space**bilaterally, bounded by**renal** (**perirenal**)**fascia**, above/medial to kidneys
+          - Composed of "body" and 2 limbs (medial and lateral)
+- ## Anatomic Relationships
+  
+  
+    - Right adrenal is usually more apical in location
+          - Lies anterolateral to right crus of diaphragm, medial to liver, and posterior to inferior vena cava (IVC)
+          - Often pyramidal in shape with inverted V shape on transverse section
+    - Left adrenal is usually more caudal and lies medial to upper pole of left kidney, lateral to left crus of diaphragm, and posterior to splenic vein and pancreas
+          - Often crescentic in shape with λ or triangular shape on transverse section
+- ## Divisions
+  
+  
+    - **Adrenal cortex**
+          - Embryologically derived from mesoderm
+          - Divided into 3 distinct zones (zona glomerulosa, zona fasciculata, and zona reticularis)
+          - Secretes **mineralocorticoids**(aldosterone) from zona glomerulosa, **glucocorticoids**(cortisol) from zona fasciculata, and **androgens**from zona reticularis
+    - **Adrenal medulla**
+          - Embryologically derived from neural crest
+          - Part of sympathetic nervous system
+          - **Chromaffin cells** secrete **catecholamines** (mostly epinephrine) into bloodstream
+    - **Vessels**,**nerves**, and **lymphatics**
+          - Arteries
+                  - **Superior adrenal arteries**: Typically 6-8; from inferior phrenic arteries
+                  - **Middle adrenal artery**: 1; from abdominal aorta
+                  - **Inferior adrenal artery**: 1; from renal arteries
+          - Veins
+                  - **Right adrenal vein** drains into IVC
+                  - **Left adrenal vein** drains into left renal vein (usually after joining left inferior phrenic vein)
+          - Nerves
+                  - Extensive sympathetic connection to adrenal medulla
+                  - Presynaptic sympathetic fibers from paravertebral ganglia end directly on secretory cells of medulla
+          - Lymphatics
+                  - Drain to **lumbar** (**aortic** and **caval**) **nodes**
+
+# ANATOMY IMAGING ISSUES
+
+- ## Multimodality Imaging Appearance
+  
+  
+    - No consensus on "normal" size or thickness of adrenals but average thickness of ~ 3 mm for medial/lateral limbs
+          - While not based on any strong evidence, > 10-mm thickness can be used as threshold for hyperplasia
+    - MR: Generally isointense to liver on T1 MR and isointense to slightly hyperintense to liver on T2 MR
+    - Ultrasound: Easiest to visualize in newborns (as result of physiologic enlargement) and become progressively more difficult to visualize with age
+          - Right adrenal gland easier to visualize than left (due to lack of liver as acoustic window and overlying bowel gas)
+          - Adrenal glands in adults usually hypoechoic (juxtaposed against hyperechoic periadrenal fat), although medulla can rarely be discretely seen and appears hyperechoic
+- ## Key Concepts
+  
+  
+    - **Adrenal** (**cortical**) **adenomas**
+          - Very common (at least 2% of general population) but usually cause no symptoms
+                  - Mostly "nonfunctioning" but identical to "functional" adenomas that cause Cushing/Conn syndrome
+          - Most adenomas contain abundant lipid (precursor to steroid hormones), allowing definitive diagnosis using CT/MR sequences that highlight lipid
+                  - Lipid is intracellular/intercellular (not macroscopic deposits of fat)
+          - Best CT technique: Nonenhanced CT with nodule measuring < 10 HU; or multiphase-enhanced CT with nodule demonstrating "washout" kinetics
+          - Best MR technique: Chemical-shift MR with signal dropout within nodule on opposed-phase images
+          - Standard imaging features for diagnosis of adenoma should be used for nodules measuring < 4 cm, while lesions > 4 cm should raise concern for malignancy
+    - **Pheochromocytoma** (tumor of adrenal medulla)
+          - Signs: Headache, palpitations, excessive perspiration
+          - 90% arise in adrenal, 90% unilateral, 90% benign
+                  - Similar tumor arising in other chromaffin cells of sympathetic ganglia is called **paraganglioma**
+          - More common with multiple endocrine neoplasia, neurofibromatosis, and von Hippel-Lindau
+          - Often markedly hypervascular in arterial phase
+    - **Adrenal myelolipoma**
+          - Uncommon benign tumor (usually incidental finding) composed of mature adipose and hematopoietic tissue
+          - Characterized by presence of **macroscopic fat**
+          - May have internal soft tissue component or calcification
+    - **Adrenocortical carcinoma**
+          - Highly aggressive malignancy with poor prognosis
+          - Large, heterogeneous mass (often with necrosis, hemorrhage, or calcification) with frequent local invasion, vascular invasion, and distant metastases
+    - **Cushing syndrome** (excess cortisol)
+          - Signs: Truncal obesity, hirsutism, hypertension
+          - Causes: Pituitary tumors (→ adrenal corticotrophic hormone), exogenous (medications) > adrenal adenoma > carcinoma
+    - **Conn syndrome** (excess aldosterone)
+          - Signs: Hypertension, hypokalemic alkalosis
+          - Causes: Adrenal adenomas > hyperplasia > carcinoma
+    - **Addison syndrome**(adrenal insufficiency)
+          - Signs: Hypotension, weight loss, altered pigmentation
+          - Causes: Autoimmune disease > adrenal metastases > adrenal hemorrhage > adrenal infection
+
+# CLINICAL IMPLICATIONS
+
+- ## Clinical Importance
+  
+  
+    - Rich adrenal blood supply due to endocrine function
+          - Results in adrenal glands being common site for hematologic **metastases** (lung, breast, melanoma, etc.)
+    - Adrenal glands respond to stress (trauma, sepsis, surgery, etc.) by secreting ↑ cortisol and epinephrine
+          - Overwhelming stress may result in **adrenal hemorrhage**or acute adrenal insufficiency (addisonian crisis)
+
+ d7703d36-250d-428e-bf99-6439a7cdc980