Lupus Site - a guide for lupus patients and their families

Also known as the Lupus Band Test.

The doctor usually takes a skin biopsy from both a sun-exposed area & an area never exposed to the sun.
The area is first injected with a local anaesthetic, then the sample is obtained with a punch, an instrument that resembles a small cookie cutter with a sharp circular edge that can be pushed through the skin.
When the punch is removed, it yields a core of tissue that is cut from its base with scissors or a scalpel.
A small scar may be left, but this fades with time.

The piece of skin is then examined at a pathology laboratory, & stained to detect specific immune reactants (IgG, IgM, IgA, complement 3 & fibrinogen).  
A confluent stain with all five proteins implies a greater than 99 % probability of having SLE; if four proteins are present, a 95 % probability; three proteins an 86 % probability; & two proteins a 60 % probability provided that IgG is one of the proteins.
In discoid lupus, only lesions (areas with rashes) display these proteins.
In SLE, most sun-exposed areas & some non-sun-exposed areas will display these proteins.  

The Lupus band test can be used to confirm that a rash is part of an immune complex-mediated reaction, which would indicate the need for anti-inflammatory therapy.
It can also be performed when a patient with a positive ANA test, but non-specific symptoms does not fulfill all the criteria for SLE but the physician feels strongly that a diagnosis must be made one way or the other in order to initiate treatment.