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

Macule

Macule

Patch

Papule

Papules

Papules

Papules

Plaque

Plaque

Plaque

Nodule

Nodule

Nodule

Tumor

Tumor

Tumor

Pustule

Pustule

Vesicle

Vesicle

Vesicle

Bulla

Bulla

Wheals

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

Scales

Scales

Crust

Crust

Excoriations

Erosion

Erosion

Ulcer

Ulcer

Ulcer

Fissure

Fissure

Atrophy

Atrophy

Atrophy

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

• Pink—Pityriasis rosea• Violet—Lichen planus• Orange—Juvenile xanthogranuloma• Blue—Amioderone skin pigmentation• Green—Pseudomonas• Yellow—Xanthomas• Black—eschar• Brown—Café 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

Keratosis Pilaris

Cherry Angiomas

• Benign vascular proliferation

• “senile hemangioma” – don’t use this term with patients

• Usually appear on trunk, start at age 30, increase with age

• Dilated capillaries

• Tx for cosmetic reasons only

http://162.129.70.33/images/cherryangioma_1_020330.jpg