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Tuesday, September 2, 2014
Calcified lymph node in lung
My 9 yr old grand daughter had a chest x-ray to check to see if she had pneumonia when they found a calcified lymph node 3cm. Seems large for a child? What causes this and is it nothing to worry about?
The vast majority of calcified mediastinal (chest) lymph nodes in children are a result of a previous infection which produces a "granulomatous" response. The swollen lymph nodes involved in the infection don't completely shrink back to their normal size, and over time calcium becomes deposited in the healing mass. This shows up as a bright white color on X-rays. The two major infections that can cause this type of response are tuberculosis and histoplasmosis. Tuberculosis, even if it appears to be "healed," needs to be treated with a long course of anti-tuberculosis medications because often a small collection of dormant "bugs" are still present that can start growing - and cause severe illness - later in life if the immune system weakens at all. Most children who have tuberculosis have a history of being exposed to an adult with tuberculosis, or who is at risk for tuberculosis (has AIDS, works in the prison system, etc..) Nevertheless, many clinicians will test a child with a large mediastinal lymph node with a PPD skin test to check for evidence of past infection, even without a suspicious exposure history. Histoplasmosis is a very common fungal infection, especially in the Ohio Valley, that is "caught" by inhaled fungal particles that are in the air. By far and away, this is the most common cause of calcified lymph nodes in children in the Ohio region. Most people who catch histoplasmosis have only mild fluish symptoms, or no symptoms at all, yet may end up with one or more calcified lymph nodes. These may persist for a long time, and no special tests or treatments are really needed. There are blood tests that can be done to check to see if a person has ever been exposed to histoplasmosis - if positive, they can bolster the theory that this infection is what caused the node to change. A 3 cm node is on the largish size - but usually still is "just histo." Beyond a PPD, the need for further evaluation really depends on whether the child is having any unusual symptoms (chronic fever, weight loss, unexplained breathing difficulty, persistent cough, etc.) Further work-up should also occur if, on a repeat CXR, the node appears to be getting bigger, even in an asymptomatic child. (Very rarely, these lesions can be due to a problem like sarcoidosis or a tumor, thus if there are unusual symptoms or unexpected growth of the lesion, more tests are warranted.)
Elizabeth D Allen, MD
Clinical Associate Professor of Pediatrics
College of Medicine
The Ohio State University