Brief Answer: Means inflammation or interstitial thickening. Detailed Answer: Hello, This is nonspecific finding; so doesn't indicate one particularly cause or diagnosis. It is generally seen with lung inflammation without pneumonia. Other important cause is previous infections or inflammation which lead to thickening of fine lung septae. As such this doesn't need any special treatment. You can be treated with symptom control medicines if you are symptomatic; else you need not be concerned. I would order for a CT scan to rule out interstitial thickening only if it is progressing or causing significant symptoms. Hope this helps. Please ask if there are doubts. Regards

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