What is the likelihood of NXP2 false positivity from a dermatomyositis in a patient who is manifesting features of morphea?   

Patient presenting with an undifferential connective tissue disease with complete rheumatology workup only notable for NXP2 detected on a dermatomyositis panel. Biopsy taken demonstrates morphea; not interface pattern consistent with DM. Other pertinent labs were negative for SCL70, centromere,

While there are ranges of sensitivities and specificities, a consulting rheumatologist feels that the NXP2 finding is incidental and likely a false-positive. Any thoughts?