How accurate is a skin biopsy for lupus? Can you have a false/ positive test result?

Lupus biopsy. Biopsy of lupus has a number of features that lead to diagnosis: a thickened basement membrane, vacuolar alteration of basal keratinocytes and superficial and deep inflammatory infiltrate. Lupus has a number of different forms in the skin and there are times when it is not easy to differentiate it from other types of skin inflammation. There are other tests to support diagnosis.