Department of Dermatology: Gross and Microscopic Pathology and Pathophysiology Part I, URMC

Gross and Microscopic Pathology and Pathophysiology Part I

Anthony A. Gaspari, M.D. and Glynis A. Scott, M.D.

Acne Vulgaris

Affects 85 to 1 per cent of the adolescent population
Begins before puberty
Continues through the 3rd decade of life
Fifteen percent of adolescents will seek medical attention
Three to five percent of acne patients will develop cystic scarring acne

Acne Lesions

Closed comedo (whitehead)
Open comedo (blackhead)
Inflammatory papule
Pustule
Cyst
Excoriation

Pathogenesis of Acne Vulgaris

Sebaceous gland hypertrophy and increased sebum production
Plugging of pilosebaceous follicle
Lipase producing P. acne hydrolyzes triglycerides in sebum to free fatty acids

Pathology of Acne:

Acne results from inflammatory reactions to keratin and sebum that have spilled into the dermis. Keratin and sebum breakdown products are highly irritating substances that excite both a neutrophilic and lymphocytic cell infiltrate. This results in intense inflammation in the dermis around the hair follicle. Eventually, it may resolve with scarring

Acne Treatment

Benzoyl peroxide
Retinoic Acid
Antibiotics
topical
systemic
Isotretinoin (Accutane^®)

Dermatitis (Eczematous Dermatitis)

Eczema to boil over Common reason for physician visit The specific diagnosis is usually made by clinical appearance rather than by histology

Common Clinical Types

Allergic contact dermatitis (i.e. poison ivy)
Irritant contact dermatitis
Atopic dermatitis
Drug related
Photoeczematous dermatitis
Erythroderma

A good example of a common form of an eczematous dermatitis is:

Allergic Contact Dermatitis (i.e. poison ivy dermatitis)

Type W immunological reaction - cell mediated
Hapten and carrier protein
Langerhans cell involved

Allergic Contact Dermatitis has three phases:

Induction phase
Elicitation phase
Immunoregulation

Histology of Dermatitis

Histologically, "dermatitis" is characterized by four features: spongiosis, acanthosis, exocytosis and hyperkeratosis (see definitions above).

Treatment of Eczematous Dermatitis

Wet dressings
Topical steroids
Systemic steroids
Avoidance
Routine skin care

Psoriasis Vulgaris

Common skin disease 1-2% of population, with three clinical variants:

Psoriasis vulgaris (common type)
Pustular psoriasis
Guttate psoriasis

Pathobiology of Psoriasis

Rapid epidermal proliferation
Inherited
Associated arthritis

Histopathology of Psoriasis:

A hyperproliferative disease that shows acanthosis and hyperkeratosis.

Psoriasis Treatment

Tar
Anthralin
Topical steroids
Systemic steroids contraindicated
Methotrexate
UVB
PUVA
Retinoids
Combination Therapy