Actinic cheilitis (AC) is a potentially malignant lesion of the lip characterized by basophilic degeneration of the extracellular matrix (ECM) as a result of chronic exposure to sunlight. This alteration, known as actinic elastosis, has not been previously characterized by histomorphometry in AC and normal lip tissues (NL). METHODS: Formalin-fixed and paraffin-embedded samples of AC (n=33) and NL (n=16) obtained from the Archives of the College of Dentistry of the University of Concepción, were stained with Verhoeff-Van Giesson technique. Elastic fibers were characterized and quantified by histomorphometry using Image J Program (NIH Image).  RESULTS: In AC, elastin fibers were disorganized and increased in thickness and collagen fibers looked degenerated.  A significant increase in elastin fibers was found in AC as compared to NL (p<0.05). The ratio between elastin/collagen fibers was also higher in AC than NL (p<0.02). However, collagen fiber density was similar between AC and NL.  A negative correlation between elastic and collagen fibers was found in AC (p<0.0001, r=0.6). Conclusions: Using histomorphometry we found a significant difference in the composition of the ECM in AC as compared to NL. This difference was mainly due to the increase in elastin fiber content in AC.

Keywords: Actinic cheilitis, Actinic elastosis, Elastin fibers, Collagen fibers, Photodamage