Effect of anatomic region on immunofluorescence diagnosis of bullous pemphigoid.

Forty-six patients with clinical and histologic criteria of bullous pemphigoid, and on whom direct immunofluorescence testing had been done, were analyzed by anatomic region of the lesions and by the region from which the immunofluorescence biopsy specimens were taken. One third of immunofluorescence tests from the lower extremities were negative, compared with only 3% from all other areas. The possible reasons for this result are discussed. The lower extremity should probably be avoided as a biopsy site for immunofluorescence in bullous pemphigoid.