Morphology and Differential Diagnosis

Welcome to Dermatology! No matter what area of medicine or surgery you pursue, you will get skin related questions from family, friends, and patients. The time frame is short, so make the best use of your time. Carry your book with you at all times and try to make it through all the photos.

Suggestions for a Successful Rotation Be on Time! Be attentive and helpful. Do not ask questions or make comments during the patient encounter. Please ask all questions outside the exam room. Please do not talk loudly in the hallway.

Macule

Patch

Papule

Papules

Plaque

Nodule

Tumor

Pustule

Vesicle

Bulla

Wheals

Special Skin Lesions Burrow: Thin linear papule or plaque Comedone: Follicular papule filled with keratinous plug which is open or closed Cyst: Papule or nodule filled with debris Telangiectasia: Dilated blood vessel less than 1 mm wide

Burrow

Comedone

Telangiectasia

Cyst

Secondary Lesions Scale Crust Erosions and ulcers Excoriations Fissures Scars Lichenification Atrophy

Scales

Crust

Excoriations

Erosion

Ulcer

Fissure

Atrophy

Scar

Lichenification

Configuration Annular Arcuate Geographic Discrete Confluent Serpiginous Linear Reticulated

Annular and arcuate

Linear

Erythema Subitum

Descriptors Punctate Lichenoid Umbilicated Scarletiniform, morbiliform Leonine

Color Pink Violet Orange Blue Green Yellow Black Brown

Color PinkPityriasis rosea VioletLichen planus OrangeJuvenile xanthogranuloma BlueAmioderone skin pigmentation GreenPseudomonas YellowXanthomas Blackeschar BrownCafé au lait spots

Color

Distribution

Morphologic categories Macular-Patch Papular Papulosquamous (scaly papules) Nodular Pustular Vesicular-bullous Urticarial Petechial Telangiectatis Burrow Poikiloderma Hyperkeratotic/scale Atrophic

More is missed by not looking than by not knowing M. McKay, M.D.

Procedures Liquid Nitrogen Electrodessication and curettage Biopsy –Punch –Shave –Excision

Seborrheic Keratosis Common Skin Tumor of unknown cause. Predilection for trunk, scalp, temples No malignant potential Increase incidence with age Easily treated with curettage or cryodestruction

Dermatosis Papulosa Nigra Most likely a subtype of seborrheic keratosis Malar areas, most commonly on African- American women

Acrocordons (Skin Tags) Common, occurring in about 25% of adults More common in obese individuals and often develop in pregnancy Frictional areas such as neck, axillae, inframammary and groin locations Can become irritated or infarcted because of torsion

Dermatofibroma Firm papule often with brown pigmentation, most frequently seen on the anterior legs Dimple sign May be a reactive process to an insect bite reaction rather than a tumor If multiple, sometimes associated with systemic lupus erythematosis

Dermatofibroma

Keloids Hypertrophic scar which extends beyond the area of injury May have delayed onset, even up to years after injury Can be painful More common in African- Americans Treatment can be difficult and choices include intralesional steroids, radiation, careful excision, laser ablation

Epidermoid Cyst

Trichilemmal (Pilar) Cyst

Actinic Keratosis

Keratosis Pilaris Follicular papules, commonly on extremities sandpaper feel 20% of the population affected Worsens in adolescence Common in Atopics and icthyosis May improve with keratolytics, retinoids, dermabrasion

Keratosis Pilaris

Cherry Angiomas Benign vascular proliferation senile hemangioma – dont use this term with patients Usually appear on trunk, start at age 30, increase with age Dilated capillaries Tx for cosmetic reasons only