SONOGRAPHIC QUANTIFICATION OF THE TYPE-IV REACTION AFTER INTRADERMAL APPLICATION OF RECALL ANTIGENS

20-MHz B-scan high-resolution sonography permits non-invasive, two-dim ensional visualisation of micromorphological structures in vivo, and a llows precise measurement of the depth and extent of inflammatory skin lesions. In 50 patients, the reactions following intradermal applicat ion of 8 recall antigens to the volar forearm were evaluated clinicall y and sonographically at various times (0, 24, 48, 72 h). In 30 patien ts, one of the inflammatory papules was excised after 48 h for complet e histological work-up (serial sections) and subsequent comparison wit h the sonographic image. Infiltrates were characterised in the ultraso und scans by the almost regular occurrence of convexity of the skin su rface, by a loosened structure (loss of echogenicity) of the cerium an d by protrusion of the cerium into the subcutaneous fatty tissue. It w as also possible to follow the dynamics of the type IV reaction with t he measurement of echogenicity (densitometry). High-frequency ultrasou nd is an objective, exact and very sensitive tool for the measurement of type IV reactions after intradermal application of recall antigens and therefore superior to clinical evaluation. The B-scan was superior to the A-scan. However, for routine evaluation of tuberculin-like rea ctions, sonography is too time-consuming. Our results suggest that den sitometry provides no additional or necessary information compared to sonometry.