Clinical, Histological and Biochemical Characterization of Hyperpigmented Lesion

Lentigo, Melasma

Hyper-pigmented spots, Lentigines, Mealsma, RNA extraction, Isolation of Keratinocytes, Isolation of Melanocytes

Hypothesis - The developments of solar lentigine and melasma are due to mutations in keratinocytes that drive the production and transfer of pigment from melanocytes to keratinocytes.

Aims - 1. Characterize and classify lentigines and mealsma from a clinical and physiological point of view. This will help us to better understand the cellular processes leading to the development of lentigines (also referred to as Senile or Solar Lentigo). 2. Proper characterization and classification of lentigines and melasma would facilitate the development of models to study and find solutions to treat these lesions. Hypothesis - The developments of solar lentigine and melasma are due to mutations in keratinocytes that drive the production and transfer of pigment from melanocytes to keratinocytes. Methodology - Patients, 21 - 80 year old, who have elected to undergo a plastic surgery will be enrolled. Some patient information (i.e. age, sex, race, family history, life-style related to sun-exposure) will be collected. After surgery, hyper-pigmented spots will be excised and stored in individual containers for subsequent experimental procedures. Before surgery, the area containing the hyper-pigmented spots will be photographed using a high resolution digital camera and assessed using optical probes (Spectrophotometer to measure skin chromophores, mexameter to measure the melanin and erythema indexes and a diffuse reflectance spectrometer to measure hemoglobin, deoxyhemoglobin and melanin). After surgery, excised skin samples will be processed for histological assessments, others for gene or protein expression analysis, and yet another group will be used to isolate keratinocyte and melanocyte to further study their behavior and response to stimuli in primary cultures. Clinical assessment of Hyperpigmented lesions: Lentigo Morphological assessment (before surgery) 1. Macules vary in color from yellow, light-brown to black, depending on under-lying skin type 2. Size varies from 1mm to greater than 1 cm 3. Appear on sun-exposed areas (face, neck, etc) Morphological assessment (before surgery) 1. Irregular light to dark brown to gray brown macules or patches on sun-exposed areas 2. When examine with Wood's lamp, melasma can be classified into 3 types, epidermal, dermal, or mixed, based on intensity of pigments, in which epidermal melasma has darker color than derma melasma. Mixed melasma has a mixture of both dark and light pigmentations 3. Melanocytes in melasma lesion have an increase in the number of mitochondria, golgi apparatus, rough ER, and ribosomes Spectrophotometer will be used to measure the optical properties of spots and control areas (without the spot) Sample processing 1. RNA extraction 2. Histology 3. Isolation of Keratinocytes, and Melanocytes.

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Singapore