Dermis and Subcutaneous Tissue

Question 1

Describe the structure and function of the dermis

Answer 1

Provides structural integrity to the skin and elasticity for response to external trauma. Varies in thickness from 1-4 mm, depending on location. Overlies and is contiguous w/ subcutaneous fact at dermal-subQ junction.

Question 2

Describe the function of the subcutaneous tissue.

Answer 2

Metabolism and protection from physical injury

Question 3

Components of the dermis

Answer 3

ECM: collagen and elastin (for support, strength, elasticity, and shape), glycoproteinds, and proteoglycans in ground substance. Also contains blood vessels, nerves, and adnexal structures (hair, sebacous glands, apocrine and eccrine sweat glands).

Question 4

Cell types found within the dermis

Answer 4

dermal dendrocytes, macrophages, fibroblasts, and mast cells.

Question 5

Primary collagen of the dermis

Answer 5

Type 1 collagen

Question 6

Role and composition of collagen in skin

Answer 6

Provides integrity and structure and accounts for 75% of dry weight of skin (12 total types).

Question 7

Mutations in collagen and enzymes for its post-translational modifications

Answer 7

Ehlers-Danlos Syndrome

Question 8

Characteristics of Type 1 (classic) Ehlers-Danlos syndrome

Answer 8

hypermobility of joints, excessive stretching of skin w/ elastic recoil, fragile skin, atrophic “fish-mouth” scars.

Question 9

Characteristics of Type 4 Ehlers-Danlos syndrome

Answer 9

involvement of blood vessels that leads to bruising and GI and arterial rupture. No tx, so minimize injury w/ no contact sports.

Question 10

Structure of elastic fibers

Answer 10

composed of elastin and fibrillin that move readily over each other for stretch and recoil.

Question 11

Pathology of Pseudoxanthoma elasticum

Answer 11

autosomal recessive disease resulting in clumping of elastin fibers. Onset in 1st or 2nd decade of life, symptoms in 3rd or 4th.

Question 12

Clinical expression of pseudoxanthoma elasticum

Answer 12

Cutaneous findings of yellow papules on lateral neck and axilla. Ocular involvement may result in decreased visual acuity or blindness (rare). CV complications of claudication, HTN, angina, and MI because of elastin fibers in medium arteries.

Question 13

Describe Marfan’s Syndrome

Answer 13

an autosomal dominant disease characterized by tall stature, disproportionately long limbs, ectopic lentis, mitral valve prolapse, aortic root dilation, aortic dissection, and possibly arachnodactyly, scoliosis, pectus excavatum, joint hypermobility.

Question 14

When a wound heals, what fibers get replaced and what fibers don’t?

Answer 14

Collagen repaired, elastin not. Less elastin leads to scar formation.

Question 15

Function of dermal blood vessels

Answer 15

circulate cellular and non-cellular material throughout the body, healing wounds, regulate temperature, control homeostasis, modulation of inflammation and leukocyte trafficking.

Question 16

Major networks of venules, capillaries, and small arterioles (2)

Answer 16

1. superficial plexus at junction of papillary and reticular dermis 2. deeper horizontal plexus along the dermal-subQ junction. Shunt blood b/w the two for flow regulation and tissue perfusion.

Question 17

Clinical appearance of Livedo Reticularis

Answer 17

reticulated macular erythema of the skin, common on lower extremities, seen on trunk and upper extremities.

Question 18

Pathology of Livedo Reticularis

Answer 18

Hypoperfusion of the skin, mostly due to cold exposure.

Question 19

Clinical appearance of Leukocytoclastic vasculitis

Answer 19

Palpable purpura (reddish-purple, domed papules that don’t blanch w/ pressure). Common in legs and ankles. Tx: elimination of causative agent. Watch renal function (a common cause)

Question 20

Pathology of Leukocytoclastic vasculities

Answer 20

Inflammation of the blood vessels, caused by medication, infection, and autoimmune disease.

Question 21

Wounds that affect the epidermis only

Answer 21

erosions

Question 22

Wounds that affect the epidermis and dermis

Answer 22

ulcers

Question 23

Type of wound arising from injury to epidermis and superficial dermis only

Answer 23

partial thickness (less scarring)

Question 24

Wounds that involve deep dermis and result in loss of adnexal structures and wounds that contract during healing

Answer 24

Full thickness

Question 25

Three phases of wound healing

Answer 25

Inflammatory (clotting, vascular permeability, and influx of neutrophils and macrophages), proliferative (fibroblasts stimulate new ECM, keratinocyte migration), and maturation.(wound contraction and remodeling)

Question 26

A firm scar that extends beyond the margins of the original wound, common in blacks and Mediterraneans.

Answer 26

Keloid

Question 27

Common sites of keloids

Answer 27

upper trunk, neck, arms, and ears.

Question 28

Treatment of keloids

Answer 28

intralesional steroids, compression, and scar massage to promote thinning and remodeling.

Question 29

The word for a "scab" that represents neovascularization for supporting healing skin

Answer 29

granulation tissue

Question 30

Local factors that interrupt healing:

Answer 30

decreased blood supply, tissue edema, infection, dry wound bed, excessive granulation tissue, chronic radiation injury

Question 31

Systemic factors that interrupt healing:

Answer 31

advanced age, malnutrition, diabetes mellitus, CT disease, other chronic illness.

Question 32

Pathology of schleroderma

Answer 32

hypocellular thickening of collagen

Question 33

Clinical expression of localized schleroderma (Morphea)

Answer 33

expanding erythematous plaques that progessively become indurated. Central portion of lesion hypopigmented and surrounded by lilac-colored ring. On trunk, no systemic disease.

Question 34

Clinical expression of limited systemic schleroderma

Answer 34

Limited: affects face and distal extremities w/ tight and thickened skin. Associated with Raynaud's phenomenon (color change in fingers and toes in cold response) Associated with CREST syndrome

Question 35

CREST syndrome

Answer 35

calcinosis cutis (calcium in skin), Raynaud's phenomenon, esophageal dysmotility, scleradactyl (induration of fingers), and telangiectasis (capillaries visible through skin)

Question 36

Clinical expression of diffuse systemic schleroderma

Answer 36

Trunk and proximal extremities. Commonly see cutaneous fibrosis, Raynaud's syndrome, pulmonary fibrosis, renal insufficiency, and cardiac disease. Poorer prognosis than limited systemic.

Question 37

Describe photoaging

Answer 37

Repeated, prolonged UV radiation exposure leading to skin atrophy, lentigines (large freckles), rhytides (wrinkles), dilated pores, and yellow quality to skin (degenerating elastin fibers).

Question 38

Describe Poikiloderma of Civatte

Answer 38

telangiectasis, hyperpigmentation, hypopigmentation, and atrophy, most common in lateral neck and V of the chest

Question 39

Focal bleeding into the skin

Answer 39

actinic purpura

Question 40

Functions of the SubQ tissue

Answer 40

insulation, energy store, and mechanical buffer

Question 41

Pathology of Panniculitis

Answer 41

inflammation of the subQ tissue. Histo shows inflammation of fibrous separation b/w fat lobules. Causes: medications, infection, sarcoidosis, inflammatory bowel disease, idiopathic.

Question 42

Clinical expression of Panniculitis and its most common subtype and tx:

Answer 42

Tender, erythematous, non-ulcerated nodules w/ ill-defined borders, most often in lowe extremities. Erythema nodosum most common subtype, a delayed hypersensitivity to Ag stimulation. Tx: eliminate causative agent, rest, elevate, compression, and NSAIDS.