Fluorescence diagnosis is a form of cancer detection based on the administration of a photosensitizer, the subsequent exposure of the tissue to light of a specific wavelength and the detection of a characteristic fluorescence. 5-aminolevulinic acid (ALA) is not a photosensitizer but the natural precursor to photosensitizer protoporphyrin IX (PpIX). We have reported PpIX fluorescence in mouse NR-S1 squamous cell carcinoma of the tongue after oral administration of ALA (400mg kg^-1) in a spectroscopic study. The aim of this study is to investigate the accumulation of ALA-induced PpIX to tumors, normal tissue, cancer cells and normal cells. Confocal laser scanning microscopic (CLSM) observation of ALA-induced PpIX was carried out at the tissular and cellular level. Strong PpIX fluorescence was revealed in the tumor tissue, clearly demonstrating the demarcation of the tumor and the normal tissues. In the normal tissues, PpIX fluorescence was pronounced in the epithelial layer, whereas no PpIX fluorescence was detected in the submucosa or muscle layer. In a study of cultured cells treated by ALA, tumor cells indicated heterogeneous distribution of intense PpIX fluorescence in the cytoplasm with nuclear exclusion, while weak PpIX fluorescence was detected in normal cells. CLSM imaging indicates that ALA-induced PpIX accumulates in the malignant tissue and cancer cells compared with normal tissue and cells. The present study supports our previous spectroscopic study.

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A 1-year-old Asian girl with a congenital melanocytic nevus on her back was seen at the outpatient clinic. Clinical examination revealed a dark brown melanocytic nevus that measured 13×11cm. Histological findings showed superficial compound nevus and there is no evidence of malignancy. The patient was treated with the normal mode ruby laser (694nm, 18J/cm2, 1 msec, 15mm 15mm) and Q-switched alexandrite laser (755nm, 7J/cm2 50 nsec, 3mm). Degree of melanin contents was measured by difference measuring apparatus before treatment and 6 months after last treatment. The improvement rate by color difference measuring apparatus is 95.4%. Histological findings showed a marked decrease in the number of the nests in the junctional, papillary and reticular dermis was observed. Thus, this treatment was considered to be an effective therapeutic method in improving color tone. Further study is needed to follow up recurrence and malignant change.

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