Histopathology and immunohistochemistry of depigmented lesions in lupus erythematosus.

BACKGROUND

Depigmented lesions (DL) have been described in areas previously damaged by inflammation in lupus erythematosus (LE). In the absence of typical lesions, distinction with other achromic diseases might be challenging. We studied the histological features and the behavior of melanocytes in these lesions.

METHODS

Tissue sections of 12 patients with lupus and DL were stained with hematoxylin-eosin, periodic acid-Schiff and Fontana-Masson. Melanocytes were counted by immunohistochemistry methods using Melan A and HMB-45. Ten biopsies of normal skin were used as controls.

RESULTS

The most common histological findings were: cellular infiltration (75%); hyperkeratosis (66.7%); thickening of basement membrane (66.7%); thinning and flattening of the epidermis (58.3%) and degenerative changes in collagen fibers (50%). Epidermal melanin and melanocytes were found in 41.7%. The melanocyte counts by HMB-45 and Melan A were significantly lower than in normal skin.

CONCLUSIONS

The DL still fulfill histological criteria for lupus. In the absence of a precise histological diagnosis, thickening of basement membrane, hyperkeratosis, cellular infiltration, epidermal atrophy and elastosis are the most common features. Loss of melanocytes and the dermal fibrosis suggests that DL in cutaneous LE behave as post-inflammatory scars.