The dermis is the dense connective tissue stroma forming the bulk of the skin. It contains blood vessels, lymphatics, nerve ending, and hair follicles. The dermis is connected to the epidermis by finger-like projections called dermal papillae. These dermal papillae form ridges (fingerprints) at the surface of the skin.

Composed of fatty connective tissue

Melanocytes produce melanin, which absorbs ultraviolet light and protects the tissue; they are in-termingled among the basal cells. Ultraviolet radiation activates melanocytes (tanning).

Langerhan cells are dendritic cells (antigen-presenting immune cells) involved with the immune system. They are found throughout the epidermis, especially the stratum spinosum.

Secrete sebum into the hair follicle and are located all over the body except he palms and soles. Oil glands found mostly on the face, neck, and upper body. Secrete sebum which is an oily, wax-like mixture of triglycerides and cholesterol. Secretes sebum by holocrine secretion whereby the entire cell content becomes excreted due to autolysis.

Bulla: Fluid-filled, elevated lesions over 0.5 cm in diameter

Burrow: An intraepidermal tunnel usually caused by insects or parasites

Cyst: Noninfected, deep-set collection of material surrounded by a histologically definable wall

Macule: Flat, circumscribed lesions measuring up to 1 cm in diameter. Cannot be felt, but can be seen.

Nodule: Circumscribed, solid, elevated lesion measuring up to 1 cm in diameter. Differs from a papule in that it has the added dimension of depth in the underlying tissue.

Papule: Circumscribed, solid, elevated lesions measuring up to 1 cm in diameter

Patch: Flat lesion measuring over 1 cm in diameter

Plaque: Circumscribed, thickened, elevated lesion over 1 cm in diameter

Pustule: A vesicle or bulla containing pus

Tumor: Circumscribed, solid, elevated lesion measuring greater than 1 cm in diameter. Differs from a papule in that it has the added dimension of depth in the underlying tissue.

Vesicle: Fluid-filled elevated lesions less than 0.5 cm in diameter

Wheal (hives): A well-circumscribed, elevated lesion that appears and disappears rapidly (minutes to hours)

Pinpoint bleeding that occurs when the scales of a psoriatic lesion are removed

Press a clear glass slide against the lesion and look for blanching. Dilated capillaries (erythema) will blanch, hemorrhagic lesions (purpura) will not.

Method of choice for diagnosis and removal of dermal and subcutaneous cysts and tumors
(epidermal cysts and lipomas) and also for malignant melanoma.

Can be used for lesions too big to punch biopsy.

A KOH test can be performed on hair, skin, or nail to diagnose dermatophytes.

A skin finding in which the top layer of skin slips away from the lower layer when slightly rubbed. An epidermal detachment produced by lack of skin cohesion, seen in Bullous Diabeticorum.

Periodic Acid-Schiff stain test is a staining method for diagnosing fungus. PAS stains polysaccharides such as the carbohydrates found in the cell wall of the fugal hyphae. The cell walls of fungi stain magenta.

Method of choice for most inflammatory or infiltrative diseases. Yields a full-thickness specimen of the skin.

Particularly suited to lesions confined to the epidermis such as seborrheic keratoses or molluscum contagiosum

Tests the small unmyelinated nerve fibers (C fibers) in the skin. With small fiber neuropathy, neurologic exam, EMG, and nerve conduction studies may be normal because they test the large nerve fibers. The ideal biopsy site is the calf at 10 cm proximal to the lateral malleolus. Two standard tests are available:

Epidermal nerve fiber density (ENFD) test: Measures the density of the small nerve fibers in the skin

Sweat gland nerve fiber density (SGNFD) test: Measures the density
of the small autonomic nerve fibers in the sweat glands. SGNFD test is a more sensitive test for small fiber neuropathy than ENFD.

Used to diagnose viral disease (herpes simplex, herpes zoster, and molluscum contagiosum)

Technique involves scraping a fluid and base of vesicle or bullae onto a glass slide. The slide is fixed with methanol and stained with Wright stain. The presence of multinucleate giant cells suggests herpes infection.

Dermatitis caused by contact with certain substances found in the environment causing inflammation of the epidermis and dermis. The most common and classic example of this is poison ivy. Another common cause is nickel, which is widely used in jewelry and in metal clasps on women’s underclothes. In podiatry, contact dermatitis is commonly due to the rubber found in the toe box of most shoes or the cement used to bind shoes together.

Dermatitis resulting from a hereditary predisposition to a lowered cutaneous threshold to pruritus. This leads to scratching and rubbing that turn into eczematous lesion. There is usually a positive family history of allergic rhinitis, hay fever, asthma, or migraine headaches. Atopic dermatitis is often exacerbated by sudden changes in temperature, humidity, and stress/anxiety, and females may have eruption just before their menstrual period.

An allergic reaction resulting in transient pruritic wheals or small erythematous papules that erupt in minutes to hours and disappear usually within 24 hours or less. Patients often have a history of atopic dermatitis. In severe reactions, anaphylaxis may occur.

Pruritic dermatitis occurring in the form of coin-shaped plaques composed of grouped small papules/vesicles on an erythematous base. Especially common on the lower legs of older males during the winter. Lesions often have an associated bacterial infection, and treatment should include oral dicloxacillin or erythromycin in addition to topical corticosteroids.

A circumscribed area of lichenification resulting from repeated physical trauma (rubbing/scratching)

Dermatitis of the lower leg related to PVD. Presents as erythematous scaling plaques with exudation, crusts, and superficial ulcers. Usually found just proximal to medial malleolus.

Symptoms include mild pruritus, pain, edema, and nocturnal cramps, and a painful ulcer may be present. Often associated with brown reticulated hemosiderin hyperpigmentation.

A special vesicular type of hand and foot eczema associated with pruritus. There is a predilection for the sides of the fingers, palms, and soles of the feet. Presents as small vesicles deep seated (appearing like “tapioca”) in clusters, occasionally bullae. Later stages present with scaling, lichenification, painful fissures, and erosions. Despite the name, sweating plays no role in the pathogenesis. There is a bullous form called pompholyx. Emotional stress and ingestion of certain metals (nickel, cobalt, or chromium) have been suggested as possible precipitating factors.

A common chronic inflammatory disorder characterized by scaling and redness, usually worse in the winter. It does not cause hair loss.

A rare disease frequently associated with GI diseases (ulcerative colitis, Crohn dz). Consists of large ulcers with characteristic purple overhanging edges, which develop rapidly from pustules and tender nodules. Exact etiology is unknown; lesions occur particularly on lower legs, abdominal, and face. Responds to systemic steroids.

A common contagious superficial skin infection seen in preschool children and young adults

Superficial pitting in the stratum corneum on the soles of the feet, giving rise to a “moth-eaten” appearance. It is the result of a keratolytic enzymes produced by bacteria. Often associated with hyperhidrosis and bromhidrosis.

A bacterial infection affecting the intertriginous areas of the body (between toes, groin, and axillae). There is a higher incidence in warm, humid climates and in diabetics. It often results as a secondary infection as a result of tinea.

An acute, severe, rapidly spreading skin infection (more specifically an infection of the connective tissue just beneath the skin). Any break in the skin can potentially result in cellulitis. Erysipelas—acute superficial form of cellulitis involving the dermal lymphatics.

A superficial contagious bacterial infection of a hair folliculitis usually caused by S. aureus. Most common on the neck, face, buttocks, and breast. Treatment involves applying moist heat to allow the lesion to come to a head and drain.