SKIN APPENDAGE INVOLVEMENT IN ANAL INTRAEPITHELIAL NEOPLASIA

Background High-grade anal intraepithelial neoplasia (AIN III) may be premalignant. Surgical excision of large areas of anal epithelium carr ies significant morbidity. Ablation treatments may carry less morbidit y; however, the depth of ablation is uncertain and failure to ablate d ysplasia in hair shafts and other skin appendages may lead to early re currence. Methods This study assesses morphometric aspects of skin app endages in perianal skin and anal canal mucosa in tissues from 30 pati ents with AIN III. Both normal and dysplastic epithelium was assessed in each patient. The depth to which AIN III involved skin appendages w as measured using computerized image analysis. Results Both the perian al epidermis and anal canal mucosa affected by AIN III were significan tly thicker than normal. Nineteen of 30 patients with AIN III had skin appendage involvement. Some 57 per cent of hair follicles (79 of 138) , 16 per cent of sebaceous glands (11 of 69) and 25 per cent of sweat glands (24 of 96) observed beneath an abnormal epithelium had evidence of AIN. The median depth of AIN involvement of the hair follicle was 1.14 (range 0.44-1.67) mm, sebaceous glands 1.44 (range 0.96-1.90) mm, and sweat glands 0.94 (range 0.50-2.20) mm. These figures do not take into account tissue shrinkage due to histological processing. Conclus ion AIN III involvement of epithelial appendages is a significant prob lem. For disease eradication, tissue destruction or removal to a depth of at least 2.2 mm below the adjacent basement membrane is required. Surgical excision of high-grade AIN remains the treatment of choice.