Positive pathergy test

What it means

With the pathergy test, a small, sterile needle is inserted into the skin of the forearm. The site of injectionis circuled and observed after one and two days. If a small red bump or pustule at the site of needle insertion occurs, the pathergy test is considered to have a positive (abnormal) result.

A positive pathergy test indicates the immune system is overreacting to a minor injury. A positive test result can be seen in Behcet disease and other conditions.

Rare diseases that can present with this2

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category