Dermatopathology

Seborreic keratosis appears to be "stuck onto" the surface of the skin. commonly it has a complex surface with numerous grooves. it may be pigmented and this should not be confused with melanoma. SK is common.; the sudden appearance of multiple, large seborrheic keratoses may be a dermatological marker of malignancy.
Seborrheic keratosis eyelid


A. This roughened, brown, waxy lesion almost appears to be "stuck on" the skin. B. The lesions consist of an orderly proliferation of uniform, benign basaloid keratinocytes with a tendency to form keratin microcysts (horn cysts).
Seborrheic keratosis


Most lesions form subtle zones of redness or sandpaper-like keratinization as seen in the lesions on the cheek, nose, and chin of this woman
Actinic keratosis

Actinic keratosis with moderate dysplasia

The lower portions of the epidermis show cytologic atypia, often with hyperplasia of basal cells with moderate dysplasia. There is hyper- and parakeratosis. Lymphocytes are present in superficial dermis

Actinic keratosis with Severe dysplasia

Sun exposure damages the skin, primarily as the result of ultraviolet light. This actinic damage is seen as a collection of abnormal collagen fibers in the upper dermis, seen here with a pale bluish appearance (basophilic degeneration) (arrows). Note the epidermal atrophy.
Solar (actinic) keratosis



A nodular and hyperkeratotic lesion occurring on the ear, unfortunately with early metastasis to a prominent postauricular lymph node (arrow).
Squamous cell carcinoma

Squamous cell ca skin

Tumor of the face with rolled edges and depressed center.

SCC of the leg with exophytic appearance.

Well-differentiated SCC showing deep invasion
The tumor is formed by atypical squamous cells arranged in orderly lobules showing large zones of keratinization.

Poorly- differentiated Squamous cell carcinoma showing spindle metaplastic features (sarcomatoid SCC)


This lesion is a prototypical pearly, smooth-surfaced papule with associated telangiectatic vessels The lesion is formed by multiple nodules of basaloid cells infiltrating a fibrotic stroma. The cells have scant cytoplasm, small hyperchromatic nuclei, and a peripheral palisade with clefting from the stroma. Note the similarity of these cells to the basal cells of normal epithelium.
Basal cell carcinoma

Nodular and pigmented basal cell carcinoma of forehead

Clinical appearance of pigmented basal cell carcinoma. Melanin is largely present in macrophages located in the stroma between tumor lobules.

a pearly pink border and an ulcerated center.

Basal cell carcinoma lower lip

Nests of basaloid cells are dropping off into the upper dermis in this example of a basal cell carcinoma of the skin.
Basal cell carcinoma solid