How much do you know about skin lesions and melanocytic neoplasms?

Overview of Skin Lesions and Melanocytic Neoplasms

• Seborrhoeic Keratosis is a benign proliferating lesion of keratinocytes that appears as a pigmented lesion protruding above the skin surface, commonly found on the trunk of adults.
• Verruca Vulgaris, also known as warts, is caused by human papilloma virus infection and appears as a firm outgrowth of keratinocytes with a ‘church spire’ architecture, commonly found on hands and feet.
• Actinic Keratosis is a very common lesion that appears on sun-exposed areas of the skin, can occur in immunosuppression, and can progress to squamous cell carcinoma in situ and invasive squamous cell carcinoma.
• Squamous cell carcinoma in-situ, also known as Bowen’s disease, appears on both sun and non-sun exposed areas of the skin, and can progress to invasive squamous cell carcinoma.
• Invasive Squamous Cell Carcinoma is a skin cancer that arises from UV light exposure, burns, radiation, and immunosuppression, and its prognosis depends on size, depth of invasion, and lymphovascular invasion.
• Basal cell carcinoma is a common skin cancer that arises from hair follicular epithelium and is commonly found on sun-exposed areas of the skin, and can be associated with syndromes such as Gorlin syndrome.
• Melanocytic Neoplasms include benign naevi (moles), dysplastic naevi, and malignant melanoma.
• Benign naevi are very common and can recur if incompletely excised, while dysplastic naevi are controversial but are important as risk factors for developing melanoma.
• Risk of melanoma is increased with larger and more atypical naevi that have irregular borders and irregular discoloration, and with multiple naevi regardless of their appearance.
• Dysplastic Naevus Syndrome is an autosomal dominant mutation affecting the CDKN2A gene, where individuals have over 100 naevi and an increased risk of melanoma.
• Malignant Melanoma is a tumour composed of malignant melanocytes invading the dermis, and its risk factors include UV light exposure, family history, multiple naevi, and immunosuppression.
• PDL1 is a protein that allows some cancer cells to avoid attack from T lymphocytes, and PDL1 inhibitors are sometimes employed to treat malignant melanoma after testing the tumour for PDL1 protein expression using a stain called PDL1 immunohistochemistry.