Dermatology Quiz on Skin Lesions

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Questions and Answers

What primarily differentiates lentigo from freckles?

Lentigo shows no change in color with sun exposure. (correct)

Freckles are a type of benign neoplasm.

Lentigo is affected by UV exposure.

Freckles have an increased number of melanocytes.

Which feature is characteristic of dysplastic nevi compared to regular melanocytic nevi?

Presence of atypical features suggesting malignancy. (correct)

Increased number of normal melanocytes.

Greater uniformity in shape.

Higher likelihood of being uniformly colored.

What describes the morphology of freckles?

Dark raised lesions with irregular borders.

Small brown/dark macules that can darken with sun exposure. (correct)

Uniform smooth texture with scaling.

Benign pigmented lesions with increased melanocyte density.

What is a key microscopic feature that helps differentiate lentigo from melanoma?

Increased melanocytes in the dermal-epidermal junction. Signup and view all the answers

What genetic alterations are associated with an increased risk of developing melanoma in dysplastic nevi?

Loss of function mutations in CDKN2A. Signup and view all the answers

What is the most common location for squamous cell carcinoma to develop?

Sun-exposed areas such as the face and ears Signup and view all the answers

Which of the following is a classic pathological finding associated with squamous cell carcinoma?

Keratin pearls Signup and view all the answers

Which risk factor is NOT associated with the development of squamous cell carcinoma?

Low-fat diet Signup and view all the answers

What effect does chronic immunosuppression have in relation to squamous cell carcinoma?

It increases the likelihood of several skin cancers, including squamous cell carcinoma. Signup and view all the answers

What distinguishes basal cell carcinoma from squamous cell carcinoma?

Basal cell carcinoma has a lower potential for recurrence compared to squamous cell carcinoma. Signup and view all the answers

What is the primary cause of actinic keratosis?

Sun exposure Signup and view all the answers

Which of the following is a characteristic feature of inclusion cysts?

Cystic expansion of epidermis Signup and view all the answers

What is the relationship between adnexal tumors and sweat glands?

Eccrine poroma is commonly found where sweat glands are numerous Signup and view all the answers

Which of the following features is associated with actinic keratosis?

Presence of retained nuclei in stratum corneum Signup and view all the answers

What is a common consequence of torsion in polyps?

Ischemic necrosis Signup and view all the answers

Which subtype of melanoma is the most common?

Superficial spreading melanoma Signup and view all the answers

What is a key characteristic of nodular melanoma compared to other types?

It grows vertically and is more aggressive. Signup and view all the answers

Which of the following describes the ABCDE criteria for melanoma detection?

Asymmetrical, Irregular border, Color variation, Diameter > 6mm, Evolving overtime Signup and view all the answers

What is one of the typical appearances of acral lentiginous melanoma?

Dark, velvety surface and well demarcated Signup and view all the answers

Which type of melanoma is often referred to as melanoma in situ?

Lentigo maligna melanoma Signup and view all the answers

Acanthosis nigricans is most commonly associated with which condition?

Insulin resistance Signup and view all the answers

Which of the following is a common location for fibroepithelial polyps?

Trunk and face Signup and view all the answers

The Leser-Trélat sign is associated with which skin condition?

Seborrheic keratosis Signup and view all the answers

Study Notes

Disorders of Hyperpigmentation (1/2)

Freckles: Small brown/dark macules (flat). Darken in sun exposure. Increased melanin. Normal melanocyte number/density.
Lentigo: Benign pigmented lesion. Increased number of melanocytes in the basal layer of epidermis. Not affected by UV/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.
Melanocytic Nevi: Benign neoplasm of melanocytes. Tan/brown pigmented lesions. Uniform color. Often round or oval shape.

Disorders of Hyperpigmentation (2/2)

Hemosiderin Hyperpigmentation: Brownish skin discoloration. Caused by deposition of hemosiderin (breakdown of hemoglobin). Induration, scaling or atrophy in chronic cases. Occurs in lower extremities (ankles and shins). Symmetrical involvement is common. Secondary to chronic venous insufficiency (CVI). Extravasation of RBCs into the dermis. Macrophages phagocytose hemosiderin. Diagnosis: Clinical based on pigmentation associated with CVI or trauma. Dermoscopy: Hemosiderin deposition. Benign. Indicates underlying venous pathology. Chronic may lead to permanent discoloration or venous ulcers.
Post-Inflammatory Hyperpigmentation (PIH): Acquired hyperpigmentation after skin injury or inflammation. Abnormal distribution of melanin in epidermis or dermis (skin's inflammatory response). Morphology: Hyperpigmented macules or patches with irregular borders. Color ranges: light brown-black (epidermal)or blue-gray (dermal). Epidermal PIH: Fades over months to years. Dermal PIH: More persistent and harder to treat.

Disorders of Hypo-pigmentation

Albinism (Oculocutaneous Albinism (OCA)): Family of genetic disorders. Autosomal recessive. Absent/reduced melanin synthesis in melanocytes. Normal number of melanocytes. Most common forms: decrease tyrosinase activity. Hypopigmentation of hair, skin, eyes. White hair, pink skin color, blue eyes. Increased risk of sunburns, Increased risk of skin cancer, No UV light protection.
Vitiligo: Acquired, localized pigment disorder. Autoimmune destruction of melanocytes.
Idiopathic Hypomelanosis (IGH): Benign condition. Asymptomatic depigmented (white) macules/patches. No clinical signs of inflammation (warmth). Treatment: steroids, immunosuppressants. Dark skinned individuals: Obvious areas of depigmentation. Light skinned individuals: Failure to tan in localized region.

Other Disorders of Skin Pigmentation

Multiple small, round or oval, hypopigmented macules. Seen in middle-aged and older adults. Results from chronic sun exposure and aging.
Affects sun-exposed areas of skin. Hypopigmented macules (lighter than surrounding skin). Smooth surface with no scaling or atrophy.

Benign Epithelial Tumors

Seborrheic Keratosis: Common benign tumors. Proliferation of immature keratinocytes. Arise spontaneously. Commonly on the trunk. Flat, well-demarcated, round or oval. Dark, velvety surface, appear "stuck on."
Acanthosis Nigricans: Hyperpigmented (dark) plaques on skin. Intertriginous sites (folds). Associated with insulin resistance. Often seen in obesity, diabetes. Rarely associated with malignancy.

Other Skin Tumors

Pityriasis Alba: Common, benign, self-limiting skin condition characterized by hypopigmented, scaly patches primarily in children and adolescents. Often in the face (cheeks) and neck, arms, and trunk. Form of atopic dermatitis associated with xerosis (dry skin. Hypopigmented light colored patches. Initially pink or red, fading to pale white over time. Fine scaling. Round, oval irregular shape (0.5-2cm). Lesions persist weeks to months, gradual repigmentation. Associated with atopic dermatitis and xerosis. Increased transepidermal water loss, dryness, and mild inflammation.

Premalignant and Malignant Epidermal Tumors

Actinic Keratosis: Premalignant skin lesions, caused by sun exposure. Growth of atypical epidermal keratinocytes; can lead to squamous cell carcinoma. Round, red/brown papules or plaques. Sun-exposed areas.
Squamous Cell Carcinoma (SCC): 2nd most common skin cancer. Arises from squamous cells in the epidermis. Occurs in sun-exposed areas (face, lips, ears, hands). DNA damage by UV light. Common in older adults (>75). Less than 5% metastasize 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 transplants, HIV, long-term glucocorticoids. Chronic skin inflammation. Burns, chronic ulcers, and draining sinus tracts. Arsenic exposure.
Basal Cell Carcinoma (BCC): Most common skin cancer. Slow growing. Rarely metastasizes. Most are found early and excised. Occur in sun-exposed areas. Lowest potential for recurrence or metastases. Pearly papules or nodules. May have telangiectasia on surface.

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Description

Test your knowledge on dermatological conditions and skin lesions. This quiz covers critical differences between lentigo, freckles, and various types of skin cancers, including squamous cell carcinoma and basal cell carcinoma. Understand key microscopic features and genetic risks associated with skin anomalies.