Disorders of Hyperpigmentation & Epidermal Tumors PDF

D13: Disorders of Hyperpigmentation (1/2) ○ 1. Discuss the definition, morphology and key points of freckles Small brown/dark macules(flat) Can darken on exposure to sun Increased amounts of melanin Normal melanocyte number/density...

D13: Disorders of Hyperpigmentation (1/2) ○ 1. Discuss the definition, morphology and key points of freckles Small brown/dark macules(flat) Can darken on exposure to sun Increased amounts of melanin Normal melanocyte number/density ○ 2. Discuss the definition, morphology and key points of lentigo Benign pigmented lesion characterized by an increased number of melanocytes in the basal layer of epidermis. Unlike freckles not affected by UV or sun exposure. Morphology: Small, flat Uniform brown, tan, or black coloration Smooth with no scaling or thickening Commonly on sun-exposed areas(face, hands, forearms) Increased melanocytes at dermal epidermal junction No nesting or clustering of melanocytes(distinguishes from melanoma) Hyperpigmentation due to increased melanin production ○ 3. Discuss the definition, morphology and key points of melanocytic nevi Benign neoplasm of melanocytes Tan/brown pigmented lesions Uniform color Often round or oval shape  Usually melanoma ○ 4. Discuss the definition, morphology and key points of dysplastic nevi Mole developing dysplasia‒>melanoma Cutaneous melanoma preceded by a dysplastic nevi Most malignant tumor of the skin Atypical features may warrant biopsy/removal  Not removed prophylactically for prevention ○ Increased risk with age >60yo(over 50% develop melanoma) ○ Acquired activation in the NRAS and BRAF genes. ○ Loss of function mutations in CDKN2A Differentiating factor from Melonoma nevi ○ 5. Discuss the definition, morphology, pathogenesis and key points of melanoma  Highly malignant form of skin cancer ABCDE asymmetrical Irregular border Color variation Diameter > 6mm Evolving overtime Types: Superficial spreading MOst common subtype 75% of melanomas  Nodular 15-30% of melanomas Aggressive subtype Grow vertically 50% melanoma deaths Lentigo maligna  Lentigo=small, flat, dark spot(large freckle) Confined to epidermis Lentigo maligna=growing dark spot confined to epidermis Sometimes called "melanoma insitu" Lentigo maligna melanoma=invasion of dermis Slow growing ‒>years to develop Spreads, darkens, becomes lumpy Occurs in elderly Acral lentiginous Least common type 50). Arise spontaneously Commonly on trunk Description: Flat Well demarcated Round or oval Dark, velvety surface Appear "stuck on"  Intraepidermal horn cysts filled with cornified cells containing keratin Leser-Trelat Sign Explosive onset of multiple itchy Seborrheic Keratosis lesions Probably caused by cytokines Associated with malignancies Gastric adenocarcinoma most common ○ 2. Discuss the definition, morphology, pathogenesis and key points of acanthosis nigricans Nigricans=darkened Hyperpigmented(dark) plaques on skin Intertriginous sites(folds) Classically neck and axillae Associated with insulin resistance Often seen in obesity, diabtes Rarely associated with malignancy  Gastric adenocarcinoma most common ○ 3. Discuss the definition, morphology, pathogenesis and key points of fibroepithelial polyps Common cutaneous lesions. Middle age-older individuals Neck, trunk, face, and intertriginous areas Morphology: Soft flesh colored bag like tumors Attached to skin by slender stalk. Fibrovascular cores(covered by squamous epithelium) Polyps undergo ischemic necrosis b/c of torsion Associated with DM, obesity, and intestinal polyposis More numerous during pregnancy‒>related to hormonal stim ○ 4. Discuss the definition, morphology, pathogenesis and key points of inclusion cysts Invagination and cystic expansion of epidermis or hair follicle Also know as wen or lump tumor Large=traumatic rupture Keratin can spill into dermis= painful granulomatous inflammatory response ○ 5. Discuss the definition, morphology, pathogenesis and key points of adnexal tumors Appendage tumor=flesh colored solitary or multiple papules and nodules. Eccrine poroma=palms and soles where sweat glands are numerous Cylindroma appendage tumor with ductal(apocrine and eccrine) occurs on forehead and scalp. Appear early in life Inactivation of tumor suppressor CYLD=Regulates transcription factor NF-kB D20: Premalignant and Malignant Epidermal Tumors ○ 1. Discuss the definition, morphology, pathogenesis and key points of actinic keratosis Solar keratosis Premalignant skin lesions Caused by sun exposure Growth of atypical epidermal keratinocytes Can lead to squamous cell carcinoma Increasing degrees of dysplasia‒>malignancy Round, red/brown papules or plaques Sun exposed areas Biopsy hyperkeratosis epidermal cell dysplasia  Perakaratosis: retained nuclei in stratum corneum ○ 2. Discuss the definition, morphology, pathogenesis and key points of squamous cell carcinoma 2nd most common skin cancer Arises from squamous cells in epidermis Occurs in sun-exposed areas Face, lip, ears, hands DNA damage by UV light Occurs in older pts Rare 75 yo Less than 5% metastastisize to regional nodes Rarely metastasize beyond nodes Red, scaling plaques with sharp borders More advanced lesions: ulcerate, keratin production May crust or bleed Risk factors Sun exposure Chronic immunosuppression Organ transplant, HIV, long term glucocorticoids Chronic skin inflammation Burns, chronic ulcers, draining sinus tracts Arsenic exposure Found in contaminated drinking water  Pathology: classic finding=keratin pearls ○ 3. Discuss the definition, morphology, pathogenesis and key points of basal cell carcinoma Most common skin cancer Slow growing Rarely metastasize Most found early and excised Occur in sun-exposed areas Lowest potential for recurrence or metastases Basal