Info
🌱 來自: Huppert’s Notes
Common Skin Cancers🚧 施工中
Common Skin Cancers
Benign skin conditions
• Seborrheic keratosis (SK): Benign pigmented neoplasm; common after age 50 yr; presents as tan-brown “stuck on” papules or plaques. Sudden appearance of multiple SK’s is associated with underlying malignancy (Leser-Trelat sign). Treatment: Cryotherapy or shave removal if symptomatic.
• Melanocytic nevi (“mole”): Benign neoplasm composed of melanocytes; can occur anywhere on the body and can mimic melanoma. Treatment: Biopsy to rule out melanoma if concerning appearance.
• Acrochordon (“skin tag”): Skin-colored pedunculated papules on the neck and skin folds; associated with obesity and insulin resistance. Treatment: Cryotherapy or snip excision.
• Cherry angioma: Benign vascular lesion that presents as a red-violaceous papule
• Dermatofibroma: Benign fibrohistiocytic lesion; presents as a tan-brown papule that “dimples” with pressure; often on the lower extremities; F>M
Basal cell carcinoma (BCC)
• Epidemiology: Most common skin cancer; due to UV light exposure; rarely metastasizes but can cause significant local tissue destruction
• Clinical features: Presents as a pearly nodule with arborizing telangiectasias and ulceration (nodular type, most common), a pink-red patch (spreading type), or shiny black-blue papules (pigmented type)
• Diagnosis: Confirm histologically with biopsy
• Treatment: Surgical excision (standard versus Mohs), electrodessication and curettage, or topical chemotherapy
Actinic keratosis (AK)
• Definition: Precancerous lesion of the epidermis (<5% progress to squamous cell skin cancer)
• Clinical features: Presents as pink, scaly, “sandpaper-like” papules and plaques in sun exposed areas
• Treatment: Cryotherapy, topical 5-FU, imiquimod
Squamous cell carcinoma (SCC)
• Epidemiology: Second most common skin cancer; risk factors include UV light exposure, radiation, chemicals (coal, soot, arsenic), HPV, and immunosuppression (e.g., solid organ transplantation).
• Clinical features: Presents as a pink, scaly papules, plaques, and nodules that ulcerate, bleed, and become crusty; may arise from a chronic wound/scar (Marjolin ulcer)
• Diagnosis: Confirm histologically with biopsy
• Treatment: Surgical excision (standard versus Mohs) is first line, radiation if surgery is contraindicated, systemic chemotherapy if metastasis
Malignant melanoma
• Epidemiology: Most deadly skin cancer; histologically aggressive and has a high risk of metastasis; lifetime risk is 1 in 50 individuals
• Clinical features: ABCDE – Asymmetry, Border irregularities, Color variation, Diameter >6 mm, Evolution over time
• Subtypes include:
- Superficial spreading (~70% of melanomas): Presents as variably pigmented macules with irregular borders; commonly located on the back (men) or posterior legs (women)
- Nodular (15–30% of melanomas): Presents as darkly pigmented “berry-like” papules or nodules
- Lentigo maligna (10–15% of melanomas): Presents as atypical pigmented macules, typically in chronically sun-damaged areas in older adults
- Acral lentiginous (<5% of all melanomas): Most common melanoma among dark-skinned individuals; presents as dark brown macules or patches on the palmar, plantar, and subungual surfaces (e.g., beneath the nail plate)
- Uveal melanoma: Melanoma of the eye involving the iris, ciliary body, or choroid (collectively referred to as the uvea)
- Mucosal melanoma: Rare type of melanoma that occurs on mucosal surfaces (e.g., GI tract, GU tract, respiratory tract)
• Staging: Via TNM system. Based on tumor depth, lymph node involvement, and presence of metastatic spread
• Prognosis: Poor prognostic factors include: male gender, older age, increased tumor thickness (Breslow depth), ulceration, increased tumor mitotic rate, and tumor location on head/neck
• Treatment:
- Stage I–II: Wide local excision, consider sentinel lymph node biopsy if stage IB or higher (e.g., tumor thickness ≥1 mm)
- Stage III: Wide local excision + lymph node dissection + adjuvant systemic therapy
- Stage IV: Systemic immunotherapy (nivolumab, pembrolizumab) or targeted therapy (e.g., BRAF/MEK inhibitors if BRAF V600 mutant)