Microscopic examination of a hematoxylin-eosin–stained biopsy specimen revealed a mixed inflammatory infiltrate rich in neutrophils along the perichondrium. The peripheral chondrocytes were altered, appearing more eosinophilic than usual, and they had a ragged architectural configuration. Indirect immunofluorescence using the patient's serum as a first step and fluorosceinated goat anti–human IgG as a second step revealed circulating antibodies in the patient's serum sample that bound to rabbit chondrocytes. Normal human serum produced no staining on the rabbit chondrocytes, and a first-step antibody to human collagen type II revealed a staining pattern of rabbit chondrocytes identical to that detected using the patient's serum sample.
Painful Erythematous Ear. Arch Dermatol. 2000;136(3):417-422. doi: