Segmental arterial mediolysis (SAM) is a rare disorder of the arteries characterized by the development of aneurysms, blood clots, narrowing of the arteries (stenoses), and blood collections (hematomas) in the affected distribution.SAM most commonly affects the arteries supplying the intestines and abdominal organs. Signs and Symptoms
Varies depending on the location of the affected blood vessels. Gastrointestinal System:
Acute abdominal pain (most common)
Flank pain
Nausea
Vomiting
Diarrhea
Bloody stools
Back painNervous System
Headache
StrokeThe most severe signs occur if an aneurysm ruptures potentially resulting in:
Shock
Loss of consciousness
Bleeding into the abdominal cavity
Bleeding into the brain

Mechanism
The middle layer of an artery, called the media, made of smooth muscle is damaged. Mediolysis occurs when the smooth muscle cells in the area of damage are destroyed. Small gaps are formed in the wall of the artery which then fill with blood. Gaps create weakness in the wall of the artery, allowing increasing pressure from blood to expand the gaps resulting in an aneurysm. Aneurysms have potential for rupture. Diagnosis
Often Segmental Arterial Mediolysis is diagnosed after clinical presentation with symptoms as above followed by CT angiogram or MRI demonstrating aneurysm(s). The gold standard method for confirming the diagnosis is surgical resection of the affected area of blood vessel followed by histologic investigation under a microscope. Segmental Arterial Mediolysis must be differentiated from fibromuscular dysplasia, atherosclerosis, and other systemic vasculidites including polyarteritis nodosa, Takayasus arteritis, Behcets disease, cystic medial necrosis, and cystic adventitial artery disease. Treatment
Patients presenting with bleeding into the abdominal cavity require possible blood transfusions and emergent intervention with coil embolization via catheter angiography.
Mediastinal lymphadenopathy or mediastinal adenopathy is an enlargement of the mediastinal lymph nodes. Causes
There are many possible causes of mediastinal lymphadenopathy, including: 

Tuberculosis
Sarcoidosis
Lung cancer/oesophageal cancer
Lymphangitis carcinomatosa
Cystic fibrosis
Histoplasmosis
Acute lymphoblastic leukemia
Coccidioidomycosis
Lymphoma
Whipples disease
Goodpasture syndrome
Hypersensitivity pneumonitisInflammatory response to Silicone (leaked from ruptured implants) which has migrated and collected in mediastinal lymph nodes. Silicone mediastinal lymphadenopathy. See also
Lymphadenopathy
Mediastinum
Mediastinal lymph node
Mediastinal mass
Neoplasia


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