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Flashcards in Dermatopathology Deck (48)
1

What is the function of the cornified layer of skin?

Protecting from dessication (dehydration)
-prevents evaporation

2

Main fxn of Langerhan cells

APCs
-professional antigen presenting cells

3

What is the predominant cell of the epidermis

(a) 2 main functions

Keratinocytes

(a) Fxns = barrier
-also to react to pathogen invasion of the epidermis by producing proinflammatory mediators to attract leukocytes

4

Name the layers of the epidermis

Basal --> spinous --> granular --> cornified

5

What are rete ridges?

Interdigitations btwn the epidermis and dermis
-form sign wave pattern at dermal-epidermal jxn

6

What are merkel cells?

(a) Location
(b) Function

Merkel cells

(a) in the basal cell layer of skin
(b) Nondendritic (not APCs), associate w/ free nerve endings to act as mechanoreceptors to help mediate touch

7

What are keratocanthomas?

(a) Characteristic appearance

Low grade skin tumor originating from the neck of a hair follicle

(a) Appearance = dome shaped, symmetrical, surrounded by smooth and inflamed skin

8

Histological features of psoriasis

-Regular elongation of rete ridges
-Perikeratosis = the silvery scale = nuclei in stratum corneum
-characteristic: find neutrophils in the cornified layer

9

What is perikeratosis

(a) Seen in which diseases

retention of nuclei in the stratum coreum

(a) Seen in diseases of increased cell turnover such as psoriasis and dandruff

10

Melanin

(a) Function
(b) Describe process of production and packaging

Melanin = produced by melanocytes for
(a) protection from UV rays
(b) Melanin produced by melanocytes, then transported to keratinocytes where it's packaged into melanosomes

11

What determines skin color?

Not the number of melanocytes- that differs by body site but not by skin color

Skin color determined by the type of melanin produced (certain melanin is darker than others) and by the shape of the melanosome (spherical, ovoid) that the melanin is packaged in

12

Histological description of melanoma

Sheets of nested neoplastic melanocytes- large nuclei w/ prominent nucleoli (high N:C ratio)

13

Vilitigo

(a) what is it
(b) mechanism
(c) biopsy features

Vitiligo

(a) Symmetrical depigmentation
(b) Autoimmune- lymphocytes target and destroy melanocytes
(c) on biopsy see complete absence of melanocytes

14

Albinism

Absence of pigment due to defect in melanin production

15

What is the most common cutaneous T cell lymphoma?

Mycosis fungoides

16

Describe the skin findings of mycosis fungoides

(a) Histological findign

Mycosis fungoides = most common cutaneous T cell lymphoma

fine scale --> plaque --> tumors

(a) Histologically: see tons of malignant lymphocytes in the epidermis

17

Describe the structure of the basement membrane of skin

Complex acellular basement membrane: tons of proteoglycans

Lamina lucida transversed by laminin V anchoring filaments that attach to the lamina densea (type IV collagen). Then under the lamina densa is collagen VII anchoring fibrils to the underlying dermis

Lamina lucida (laminin V) --> lamina densa (collage IV) --> collagen VII anchoring to dermis

18

What is bullous pemphigoid?

(a) Mechanism
(b) Histologically
(c) Clinically

Acquired (congenital) blistering disease
-disease of the skin basement membrane

(a) Circulating IgG targeting antigen in the lamina lucida
(b) See separation at the epidermal-dermal junction: see the epidermis lifting off the dermis
(c) Clinically: flacid bullae that may erode

19

Epidermis Bullosa

(a) Mechanism
(b) Clinically

Epidermis Bullosa

(a) mutation in collagen VII (need to anchor the lamina densa to underlying dermis)
(b) clinically get repeated erosion and scarring => loss of barrier function => frequently succumb to infection
-mitten deformity due to scarring on hands

20

What are adnexa of the skin?

Adnexa = appendages derived from an epidermal component

ex: hair, sweat, mammary glands, nails

21

What is lanugo?

Lanugo = fine hairs ubiquitous on a fetus, get replaced by vellus hair

22

Differentiate vellus and terminal hairs

Vellus hairs: thin, lack a central core structure called a medulla
-found on arms and legs

Terminal hairs = have central medulla
-hair bulb deep w/in the dermis or subcutis
-found on the scalp, groin, and axilla

23

Describe the hair cycle?

(a) Duration of each phase
(b) Total hairs, how many are shed each day?

Hair cycle: each hair undergoes an individual programmed cycle of growing and shedding

(a) growth (anagen- can last up to 5 years), cessation (catagen- around 2 weeks), and rest (telogen- around 3 months) until it falls off
(b) 100,000 total, 100 of which fall off each day

24

Distinguish the types of alopecia

(a) Areata
(b) Totalis
(c) Universalis

Alopecia = hair loss

(a) areata = hair loss in patches
(b) totalis = hair loss on scalp
(c) universalis = hair loss on entire body

25

Histological finding of hair shaft in alopecia universalis

"swam of bees" = tons of lymphocytes attacking the hair follicle
-suggests autoimmune component => alopecia pts often have concomitant AI

26

What is a tricofolliculoma?

(a) Clinically
(b) Treatment

Benign adnexal tumor (benign tumor of the pilosebaceous unit)
-see 4-5 hairs (instead of just one) w/ a single orifice

(a) Clinically: see horses tail
(b) Usually punch biopsied out for cosmetic reasons

27

Describe the hair changes seen in hirsutism

(a) Common cause

Hirsutism = vellus hairs converted to terminal hairs

(a) Endocrine abnormalities, such as high T

28

What is androgenetic alopecia?

= male-patterned hair loss = hair loss due to hair follicle shrinkage under the influence of androgenic hormones

-terminal hairs converted to vellus hairs, shorter thinner hair w/ bulb in the superficial (instead of deep) dermis

29

Sebaceous, Eccrine, and Apocrine glands

(a) location
(b) type of secretion

Sebaceous Glands
(a) Diffuse except for palms and soles
(b) Holocrine secretion

Eccrine glands
(a) Diffuse, especially on hands and soles
(b) Merocrine secretion- by exocytosis

Apocrine glands
(a) Limited to axilla and groin
(b) Secretion by decapitation- snout pinches off

30

Function of sebum

(b) Ma

Sebum (holocrine secretion from sebaceous glands everywhere but palms and soles)

Fxn = temp regulation, waterproofing, bacteria and fungicidal

31

What disease process is sebum involved in?

Acne vulgaris
-sebum production stimulated by androgens (usually DHT) that mixes w/ bacteria and inflammation => rupture of the follicle wall that evokes an intense inflammatory response

32

Describe the innervation of eccrine glands?

(a) Name two stimulants
(b) Composition of eccrine secretion
(c) Main fxn of eccrine gland secretion

Eccrine glands are innervated cholinergically (parasymp)

(a) By environment (ex: it's hot outside), and emotions
(b) Eccrine secretion is hypotonic to plasma. Starts off as isotonic but as it approaches the surface NaCl is reabsorbed
(c) Temperature regulation (via evaporative cooling)

33

Which type of gland in the skin has a corkscrew appearance?

Eccrine gland duct courses thru the dermis and has a corkscrew appearance in the epidermis as it approaches the surface

34

Effect of blocked eccrine glands

(a) Miliara rubra
(b) Miliaria crystallina

Eccrine gland blockage => small itchy rash in hot/humid conditions classified by the top level of sweat gland obstruction

(a) Miliara rubra = obstruction of eccrine ducts at the epidermis, causing leakage of sweat into deeper layers of epidermis provoking local inflammatory rxn => itchy red rash
= 'heat rash' or 'sweat rash'

(b) Miliaria crystallina = most superficial obstruction (eccrine ducts obstructed at the cornified layer), presents asymptomatically w/ tiny blisters (look like sweat inside)

35

What is the cause of body odor?

Bacterial action upon secretions of apocrine glands
Apocrine glands are limited to the axillae and groin => armpits get smelly

36

How are apocrine glands innervated?

Apocrine glands are innervated adrenergically

Ex: sympathetic activation causes you to sweat when running from a bear

37

What is hidradenitis suppurativa?

Disease of the apocrine sweat glands
= Hyperkeratosis in an apocrine-gland containing follicle (so in the axilla or groin) => bacterial overgrowth => ruptured follicle causes huge immune response => abscesses and boil like lesions

38

Fxn of the dermis

Structural and nutritional support for the epidermis
-contains blood vessels in plexuses

39

Pacinian's and Meisner's corpuscles

(a) Fxn
(b) Location

Pacinian's corpuscle
(a) mechanoreceptors for vibration and pressure
(b) Lower dermis

Meisner's corpuscle
(a) Mechanoreceptors for fine touch
(b) Upper dermis

40

Composition of the dermis

(a) what types of collagen
(b) what fibers to support BVs
(c) what fibers to allow for recoil
(d) Fxn of ground substance

Dermis

(a) 85% collagen I, 15% collagen III
(b) Reticulin to support BVs and hair follicle
(c) Elastin for recoil
(d) Ground substance = lubrication and bulk for shock absorption

41

Ehlers-Danlos syndromes

(a) What are they
(b) Clinical presentation

Ehler's-Danlos syndromes = diseases caused by defects in collagen structure in the dermis

(a) inherited CT disorders of the structure, production, or processing of collagen
(b) clinically present w/ hyperextensible skin, increased joint mobility, Marphenoid habitus
-but elastin is intact => skin maintains normal recoil

42

Cutis Laxa

= molecular defect in elastin => loss of skin recoil

-little babies that look like Sharpay puppies

43

What is morphea?

Localized scleroderma
-excessive collagen deposition (by overactive fibroblasts) leading to thickening of the dermis and subcutis

44

Dermatofibroma vs. Dermatofibrosarcoma

Dermatofibroma = benign well-circumscribed proliferation of fibroblasts

Dermatofibrosarcoma = rare malignant neoplasm of the dermis
-malignant counterpart of dermatofibroma

45

Angiosarcoma

= malignant neoplasm of endothelial-type cells lining vessel walls
= cancer of the inner lining of blood vessels
-one of the most common locations is on the skin

46

Subcutis

(a) Structure
(b) 3 fxns

Subcutis

(a) Structure = lobules of adipocytes separated by vascularized fibrous septae
(b) insulates against heat loss, cushions for mechanical injury, stores dense energy

47

Pannuculitis

(a) Most common pannuculitis

Pannuculitis = group of diseases caused by inflammation of the subcutaneous adipose tissue
-inflammatory process of the subcutis

(a) Most common pannuculitis = erythema nodusum = presents as red tender nodules on the shins

48

Lipoma vs. liposarcoma

Lipoma = benign tumor of mature adipocytes
-most common benign form of soft tissue tumor

Liposarcoma = very rare malignant tumor arising from fat cells