Hyperpigmented small spots induced by long-term PUVA therapy. A clinical, light and electron microscopic study

Area of Science:

• Dermatology
• Photobiology
• Histopathology

Background:

• Photochemotherapy (PUVA) is a common treatment for various skin conditions.
• PUVA therapy involves exposure to ultraviolet A (UVA) light in conjunction with a photosensitizing agent (psoralen).
• Adverse skin reactions can occur following PUVA treatment.

Purpose of the Study:

• To investigate the cause of persistent disseminated hyperpigmented small spots observed in patients treated with PUVA.
• To analyze the histological, histochemical, and ultrastructural changes associated with these PUVA-induced spots.
• To compare these findings with other light-induced hyperpigmentations.

Main Methods:

• Histological, histochemical, and electron microscopy studies were conducted on skin biopsies from affected patients.
• Analysis of melanocyte count, activity, and pigment transfer.
• Comparison of lesional skin with interlesional skin and other light-dependent hyperpigmentations.

Main Results:

• A significant increase in melanocytes and hyperactivity of melanocytes were observed in the hyperpigmented spots.
• Increased pigment transfer to dermis and keratinocytes was noted.
• Evidence of melanocytic damage, including binucleated cells, was present, with some changes persisting for at least 7 months post-treatment.

Conclusions:

• PUVA therapy can induce persistent hyperpigmented spots characterized by melanocytic hyperactivity and damage.
• The observed alterations suggest a complex response to PUVA, involving both epidermal and dermal components.
• These findings contribute to understanding the long-term dermatological side effects of photochemotherapy.