Histological Examination of Bronchial Mucosa after Photodynamic Therapy Showing no Selectivity of Effect between Tumour and Normal Mucosa

.After the treatment for early stage bronchogenic carcinoma including carcinoma in situ with photodynamic therapy (PDT), the degree of bronchial mucosal damage was studied histologically. The influence of treatment modality on bronchial mucosa was also examined. Few studies of histological changes of bronchial mucosa caused by PDT have been done. The histological specimens of bronchial mucosa in patients who received PDT and had a complete response were reviewed retrospectively. Twenty-three patients with 24 carcinomas including six carcinomas in situ had been treated with PDT using argon dye laser, excimer dye laser with or without additional radiotherapy. The degree of epithelial and subepithelial changes was classified as normal, hyperplasia, metaplasia and as mild, moderate and marked fibrosis, respectively. Subepithelial fibrosis was seen after PDT in almost all cases even when the tumour was entirely superficial to this layer. As a whole, epithelial change was found to be hyperplastic in three and metaplastic in 13 cases. Subepithelial fibrosis were found to be mild in four, moderate in 13, and marked in four cases. No differences were seen between the effects with the excimer and argon dye lasers. As used at present, PDT in the bronchi has no selectivity between normal and tumour tissue but may have advantages over other techniques due to the lack of cumulative toxicity and the excellent healing. Received for publication 15 September 1997; accepted following revision 23 February 1998