dermatologic disorders
Diagnostic Tests for Skin Disorders
Diascopy
Diascopy is used to determine whether erythema in a lesion is due to blood within superficial vessels (inflammatory or vascular lesions) or is due to hemorrhage (petechiae or purpura). A microscope slide is pressed against a lesion (diascopy) to see whether it blanches. Hemorrhagic lesions do not blanch; inflammatory and vascular lesions do. Diascopy can also help identify sarcoid skin lesions, which, when tested, turn an apple jelly color. 