Acute interstitial pneumonitis is a rare, severe lung disease that usually affects otherwise healthy individuals. There is no known cause or cure. Acute interstitial pneumonitis is often categorized as both an interstitial lung disease and a form of acute respiratory distress syndrome (ARDS) but it is distinguished from the chronic forms of interstitial pneumonia such as idiopathic pulmonary fibrosis. Symptoms and signs
The most common symptoms of acute interstitial pneumonitis are highly productive cough with expectoration of thick mucus, fever, and difficulties breathing. These often occur over a period of one to two weeks before medical attention is sought. The presence of fluid means the person experiences a feeling similar to drowning. Difficulties breathing can quickly progress to an inability to breathe without support (respiratory failure).Acute interstitial pneumonitis typically progresses rapidly, with hospitalization and mechanical ventilation often required only days to weeks after initial symptoms of cough, fever, and difficulties breathing develop. Diagnosis
Rapid progression from initial symptoms to respiratory failure is a key feature. An X-ray that shows ARDS is necessary for diagnosis (fluid in the small air sacs (alveoli) in both lungs). In addition, a biopsy of the lung that shows organizing diffuse alveolar damage is required for diagnosis. This type of alveolar damage can be attributed to nonconcentrated and nonlocalized alveoli damage, marked alveolar septal edema with inflammatory cell infiltration, fibroblast proliferation, occasional hyaline membranes, and thickening of the alveolar walls. The septa are lined with atypical, hyperplastic type II pneumocytes, thus leading to the collapse of airspaces.
Vitelliform macular dystrophy is an irregular autosomal dominant eye disorder which can cause progressive vision loss. This disorder affects the retina, specifically cells in a small area near the center of the retina called the macula. The macula is responsible for sharp central vision, which is needed for detailed tasks such as reading, driving, and recognizing faces. The condition is characterized by yellow (or orange), slightly elevated, round structures similar to the yolk (Latin vitellus) of an egg. Genetics
Best disease is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In most cases, an affected person has one parent with the condition. The inheritance pattern of adult-onset vitelliform macular dystrophy is definitively autosomal dominant. Many affected people, however, have no history of the disorder in their family and only a small number of affected families have been reported. This is because the penetrance of the condition is incomplete; therefore, it is possible for an individual to have a copy of the mutant allele and not display the VMD phenotype. The ratio of males to females is approximately 1:1. Pathophysiology
Mutations in the RDS and VMD2 genes cause vitelliform macular dystrophy. Mutations in the VMD2 gene are responsible for Best disease. Changes in either the VMD2 or RDS gene can cause the adult-onset form of vitelliform macular dystrophy; however, fewer than a quarter of cases result from mutations in these two genes. In most cases, the cause of the adult-onset form is unknown.