Dermatopathology

Question 1

Skin

Answer 1

Epidermis = Stratified keratinocytes
-Stratum corneum (Pink keratin in anucleate cells)
-Stratum granulosum (With granules)
-Stratum spinosum (Desmosomes)
-Stratum basalis (Stem cells)

Basement membrane (Hemidesmosomes)

Dermis

Question 2

Atopic Dermatitis (Eczema)

Answer 2

HSR 1 with pruritic, ery, oozing rash with vesicles and edema

FACE & FLEXOR surfaces
+Asthma, allergic rhinitis

Topical steroid

Question 3

Contact Dermatitis

Answer 3

Pruritic, ery, oozing rash with vesicles and edema

Upon exposure to allergen or irritant

-Poison ivy, nickel jewelry (Type 4 HSR)
-Detergents
-Drugs, ie PCN

Remove offending agent
Topical steroid

Question 4

Acne Vulgaris

Answer 4

Comedones, pustules, nodules

Chronic inflammation of follicles & sebaceous glands
-Hormone-increase in sebum
-Excess keratin blocks follicles
-Forms comedones

P. acnes
-Causes inflammation
-Forms pustules or nodules

BP (Antimicrobial)
Vit A (Decrease keratin prouced)

Question 5

Psoriasis

Answer 5

Well-circumscribed, salmon colored plaques with silvery scale

SCALP & EXTENSOR surfaces, pitting nails

Due to excessive keratinocyte proliferation
Possibly autoimmune (HLA-C & triggered by trauma)

Steroids
Immune-modulating therapy
UVA light with psoralen (PUVA)

Question 6

Lichen Planus

Answer 6

Pruritic, planar, polygonal, purple papules
+Reticular white lines, Wickham striae

Oral mucosa, elbows, wrists

Associated with chronic hep C infection, but etiology unknown

Question 7

Pemphigus Vulgaris

Answer 7

Autoimmune destruction of desmosomes; IgG against desmoglein

Acantholysis of stratum spinosum
“Tombstone appearance”
Bullae rupture easily

Skin & oral mucosa

Question 8

Bullous Pemphigoid

Answer 8

Autoimmune destruction of hemidesmosomes; IgG against basement membrane

Supepidermal blisters, bullae do NOT rupture easily
Oral mucosa is spared

Question 9

Dermatitis Herpetiformis

Answer 9

Autoimmune deposition of IgA at tips of dermal papillae

Pruritic vesicles and bullae in groups, resembling HSV
Seen in celiac disease

Question 10

Erythema Multiforme

Answer 10

HSR with targetoid rash & bullae
~HSV infection

Steven-Johnson Syndrome (SJS)
-Skin + oral mucosa + fever

Toxic Epidermal Necrolysis (TEN)
-Diffuse sloughing of skin, resembling SSS
-Adverse drug rxn
-Medical emergency!

Question 11

Seborrheic Keratosis

Answer 11

Benign proliferation of SQ cells with pseudocysts
Classic “stuck-on” appearance
Common in elderly

Leser-Trelat Sign
-Sudden onset of mulitple SK’s
-Underlying carcinoma of GIT

Question 12

Acanthosis Nigricans

Answer 12

Epidermal hyperplasia with darkening of skin, “velvet-like” skin

Axilla, groin

Seen in insulin resistance or malignancy

Question 13

Basal Cell Carcinoma

Answer 13

Malignant proliferation of stratum basalis
Especially on UPPER lip

“Peripheral palisating” ***

Surgical excision

Risk: Prolonged exposure to sunlight, albinism, xeroderma pigmentosum

Question 14

Squamous Cell Carcinoma

Answer 14

Malignant proliferation of SQ cells
Ulcerated, nodular
LOWER lip

Surgical excision

Risk: Same as BCC’s
+ Immunosuppressive therapy
+ Arsenic poisoning
+ Chronic inflammation (burn scars, draining sinus tracts)

Question 15

Actinic Keratosis

Answer 15

Hyperkeratotic, scaly papule/plaque
Precursor to SCC

Question 16

Keratoacanthoma

Answer 16

Well-differentiated SCC
Develops rapidly & regresses spontaneously

“Cup-shaped” tumor with keratin debris

Question 17

Melanocytes

Answer 17

Derived from neural crest
Found in stratum basalis
Synthesize melanin in melanosomes
Transfer melanosomes to keratinocytes

Question 18

Vitiligo

Answer 18

Autoimmune destruction of melanocytes
Loss of skin pigmentation & tanning

Question 19

Albinism

Answer 19

Congenital defect in tyrosinase; Impaired melanin production

Ocular or oculocutaneous

Increased risk of skin cancer

Question 20

Freckle

Answer 20

Small tan-brown macule
Darkens when exposed to sunlight

Due to increased number of melanoSOMES

Question 21

Freckle

Answer 21

Small tan-brown macule
Darkens when exposed to sunlight

Due to increased number of melanoSOMES

Question 22

Melasma

Answer 22

Mask-like hyperpigmentation of cheeks
Seen in oral contraceptives & pregnancy

Question 23

Nevus (Mole)

Answer 23

Benign neoplasm of melanocytes

May be congenital (with hair growing from it)
***Melanoma would NOT have hair

May be acquired
-Along epidermal-dermal junction (Junctional Nevus)
-Extends into dermis (Compound Nevus)
-Loses junction (Intradermal Nevus)

Dysplasia within nevus, precursor to melanoma

Question 24

Melanoma

Answer 24

Malignant neoplasm of melanocytes
Know the ABCDE’s, Diameters > 6 mm

Risk: Same as BCCs
+ Dysplastic Nevus Syndrome (AD)

Question 25

Melanoma Subtypes

Answer 25

Superficial Spreading Melanoma
-Dominant early radial phase
-Good prognosis

Nodular Melanoma
-Early vertical phase
-Poor prognosis

Acral Lentiginous Melanoma
-On palms, soles
-Often of darker skin patients
-NOT related to UV light exposure

Question 26

Impetigo

Answer 26

S. aureus or S. pyogenes
Seen in kids, especially face

Erythematous macules to pustules
Erosions with dry honey-crusted serum

Question 27

Cellulitis

Answer 27

(Deep infxn of dermis) S. aureus or S. pyogenes
Ery, swollen, tender rash
+Fever

Risk: Trauma, surgery, insect bite

***Necrotizing fasciitis
-Progress to necrosis of subq tissue
-Anaerobic “flesh-eating” bacteria
-CO2 production, crepitus
-Surgical emergency!

Question 28

(Staphylococcal) Scalded Skin Syndrome

Answer 28

(Superficial infxn) Staph aureus
Exfoliative A & B toxins separate skin at stratum granulosum***

Sloughing of skin with RED rash
+Fever

DDX: Toxic Epidermal Necrolysis (TEN)

Question 29

Verruca

Answer 29

Flesh-colored papule with rough surface
Especially at hands, feet

Due to HPV infection of keratinocytes

Question 30

Molluscum Contagiosum

Answer 30

Firm, pink, UMBILICATED papule

Seen in kids, sexually active adults, immunocompromised patients

Due to POXvirus

“Molluscum bodies” seen within keratinocytes