Miliary tuberculosis

Miliary tuberculosis (or disseminated TB) is a form of tuberculosis that is characterized by a wide dissemination into the human body and by the tiny size of the lesions (1-5 mm). Its name comes from a distinctive pattern seen on a chest X-ray of many tiny spots distributed throughout the lung fields with the appearance similar to millet seeds, thus the term "miliary" tuberculosis. Miliary TB may infect any number of organs including the lungs, liver, and spleen. It is a complication of 1-3% of all TB cases.^[1]

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Etiology

Miliary tuberculosis forms from a tuberculous infection in the lung that can erode into a pulmonary vein. Once the bacteria reach the left side of the heart and enter the systemic circulation and seed organs such as the liver and spleen. Alternately the bacteria can enter a lymph node and then drain into a systemic vein and eventually reach the right side of the heart. From the right side of the heart, the bacteria may re-seed the lungs, causing the eponymous "miliary" appearance.

Signs and Symptoms

A patient with miliary tuberculosis will tend to present with non-specific signs such as low grade fever, cough, and generalized lymphadenopathy. Miliary tuberculosis can also present with hepatomegaly (40% of cases), splenomegaly (15%), pancreatitis (<5%), and multiorgan dysfunction with adrenal insufficiency.^[1] Also can be diarrheal in nature and appearance.

Treatment

See: Tuberculosis treatment

Miliary TB is a serious condition; untreated miliary TB is almost always fatal. About 25% of patients with miliary TB also have tuberculous meningitis. The standard treatment recommended by the WHO is with isoniazid and rifampicin for six months, as well as ethambutol and pyrazinamide for the first two months. If there is evidence of meningitis, then treatment is extended to twelve months. The US guidelines recommend nine months' treatment.^{[citation needed]}

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