To develop a biophysical model the investigators will recruit patients based on their known histopathology diagnoses, from each of 6 skin-cancer categories: basal cell carcinoma, squamous cell carcinoma, melanoma, atypical nevus, actinic keratosis, and benign skin. Patients with non-cancer diagnosis such as psoriasis, eczema / dermatitis, lichen planus or lupus will also be recruited. Recruitment will include 5 patients from each of these categories, giving a total of 20 patients. Measurements for the biophysical models are conducted on skin tissues that have been excised from the patients. Furthermore, these skin tissues are excised tissues that under standard screening procedure will be biopsied by the dermatologist. Therefore, patients are not undergoing extra & unnecessary biopsies, and will not be exposed to any risk involved with the microspectroscopy measurements.