Integumentary System

Question 1

Factors considered when managing a wound

Answer 1

Type of injury, location, degree of contamination, age of the wound, blood supply, and skin lost

Question 2

Types of vessels supplying the skin

Answer 2

Perforating musculocutaneous vessels pass through the muscle to supply skin

Direct cutaneous vessels run subdermally and parallel to the skin surface and closely associated with the panniculus muscle

Question 3

The normal tension of the skin is the result of what

Answer 3

Elastic fibers in the dermis and is the reason skin edges retract when incised

Question 4

What influences skin tension lines

Answer 4

Skin is anisotropic (lack similar properties in all directions) and is influenced by muscle contraction, movement of joints and other external forces

Question 5

list some of the particulars when suturing tissue

Answer 5

Tissue strength and not suture size or number are more important determinants for dehiscence

Suture should be placed as close together as necessary

More sutures are required in thin skin

Wounds under tension increasing suture number is preferable to increasing size

Question 6

Describe the corner suture

Answer 6

Begins like a routine horizontal mattress but instead of penetrating full thickness, only a partial thickness bite is taken, then is passed horizontally through the dermis at the point of the V and is completed as it was started

Is also called three-point or half-buried mattress suture

Is used to secure the sharp intersecting point of a Y-shaped incision

Question 7

Describe the particulars of tension-relieving patterns

Answer 7

If the force required on individual sutures to appose skin edges increases to the point where vascular supply is compromised tension sutures can be used

Used either alone or in combination with appositional patterns

Question 8

Explain the reason why sutures should be placed at least 0.5 cm from skin edges

Answer 8

Collangenolytic and inflammatory processes that take place during early wound healing weaken the suture-holding ability of the skin

Question 9

Discuss undermining skin

Answer 9

Simplest tension-relieving procedure, blunt dissection has the advantage of minimizing damage to the cutaneous blood supply over sharp dissection

Depth at witch skin is undermined depends on vascular supply

In a fresh wound a distance equal to the width of the defect should be elevated on each side of the wound and can be extended half as much again if needed

Question 10

Discuss tension-release incisions

Answer 10

Are longitudinal incisions made adjacent to the wound margin which aids in advancing skin to cover the wound

When the tissue between the wound edge and incision is undermined the elevated skin acts as a bipedicle advancement flap

Can be made on either side of the incision or both sides, when making a single release incision it should be placed at a distance approximately the width of the wound away from the wound edge

When creating two release incisions the resultant size of each new wound is approximately half of the original wound area and is preferred over one release incision

Question 11

Discuss mesh expansion

Answer 11

Simple technique that when combined with undermining can increase the amount of skin available for mobilization

Small incisions made in staggered rows parallel to wound edge made approximately 1 cm between individual stab incisions and adjacent rows

Question 12

Explain V-to-Y and Y-to V plasty

Answer 12

V-to-Y requires a V-shaped incision with the point of the V directed away from the defect to be closed, closure of the V incision is done by converting it to a Y

Question 13

Discuss Z-Plasty

Answer 13

Used to relieve tension from a linear scar, change orientation of an incision line or scar or to relieve tension when closing a large defect by recruiting loose tissue from the sides of the surgical site

Represent a modification of a transposition flap

Result in a change in orientation of the central limb of the Z and a gain in length

Z is symmetric with the 3 limbs of equal length and the same angle between the two arms and the central limb

An angle of 60° is most frequently used which result in 75% gain in length

Most common complication is ischemia and necrosis of the tips of the triangular flaps

Question 14

Explain W-Plasty

Answer 14

Designed to improve the cosmetic appearance of a scar

Scar is excised by making a series of opposing zigzag incisions in such a way that when sutured the incision will interdigitate

Question 15

Discuss presuturing

Answer 15

Is based on the principle that skin stretch when is held in tension

It relies on the physiologic response of mechanical creep which result in skin expansion and can be achieved when sutures are placed several hours prior to removal of a skin lesion

Question 16

Discuss Elastomers

Answer 16

Consist of a silicon pouch that can be gradually inflated percutaneously with sterile saline

Take advantage of both mechanical and biological creep and can expand the area of the skin 2-3 fold, epidermis respond to gradual inflation by an increase in mitotic activity and a net increase in epidermal tissue

Complications include pain, pressure necrosis, implant failure, wound dehiscence, and premature exposure of the expander

Question 17

Describe closure of fusiform excisions

Answer 17

Can be used for elective scar revision with the long axis of the defect being oriented parallel to the lines of skin tension

A 3:1 or 4:1 length to width ratio will allow closure of the defect with fairly even distribution

Question 18

Describe closure of circular defects

Answer 18

Commonly result in the formation of dog ear

Can be converted to an X or a Y-shape by tightening sutures placed at 3 or four points equidistant to each other around of the circumference of the defect

Excision of two triangles on opposite sides of the circle therefore creating a fusiform defect

The height of each triangle should be at least equal to the diameter of the circle resulting in removal of skin equivalent to 1.5 times the area of the original defect

Double S-shaped incision with a bi-winged excision, bow tie and combined V-incision are alternative methods

Question 19

Describe skin flaps

Answer 19

Skin flaps or pedicle graft is a portion (flap) of skin that when created, can be moved from its original location to a second location on the body while by virtue of its attachment (pedicle) it maintains vascular supply

Question 20

Describe the classification of skin flaps

Answer 20

Local or distant depending on the relationship of the donor site to recipient site

Local flaps include rotation flaps, transposition flaps and interpolating flaps

Also categorized as random or axial pattern flaps according to the nature of their vascular supply

Random pattern flaps do not have defined vascular pattern depend on the subdermal plexus for survival

Axial pattern flaps contain at least one major direct efferent and efferent cutaneous vessel

Question 21

Discuss the length to width ratio

Answer 21

Random patter flaps length to width ratios from 1:1 to 3:1 for single pedicle and 1.5:1 to 3:1 for bipedicle

Question 22

Describe the delay phenomenon

Answer 22

Used to enhance the blood supply to the skin to increase the chances of survival

Two stage technique involves incising and undermining the skin and subcutaneous tissue of the proposed flap and leaving it sutured in its original location for a period of time

Question 23

Describe advancement flaps

Answer 23

Are random pattern flaps that can be either the single or bipedicle type a V-Y plasty is an example

Simple bipedicle flaps are performed either by making a single longitudinal incision on one side of the wound or by incision on each side of the defect

Question 24

Discuss rotating flaps

Answer 24

3 types are described rotation, transposition, interpolating

Rotation flap involves creating a semicircular incision and moving the tissue laterally

A rectangular single pedicle flap that is created adjacent to the defect and subsequently rotated on its pedicle is called transposition

Moving a similar rectangular flap onto an immediately adjacent defect creates an interpolating flap

Question 25

Most common indications for applying skin grafts

Answer 25

Large wounds that cannot heal by any other means

Question 26

Discuss the classification of free grafts

Answer 26

Can be classified by their source in autograft (isograft), allograft (homograft) and xenograft (heterograft)

By their thickness in full-thickness composed of epidermis and entire dermis, split-thickness composed of epidermis and only a portion of the dermis

Full or split thickness free skin grafts can be applied as a solid or meshed sheets or they can be embedded in granulation tissue as pinch, punch, or tunnel grafts

Question 27

Factor that would influence graft acceptance

Answer 27

Percentage of dermis within the graft

The thickness of dermis within the graft is directly proportional to the graft’s durability and cosmesis but inversely proportional to the graft’s ability to survive

Question 28

Describe how a graft adhere to recipient site

Answer 28

Adhere by fibrin which binds to collagen within the graft

Vessels and fibroblast invade the fibrin matrix by day 4-5

Graft becomes firmly adhere around day 10

Question 29

Describe neovascularization of a graft

Answer 29

New capillaries from the recipient bed invade preexisting vessels within the graft, and others cut new vascular channels into the dermis

Question 30

Explain vascular bridging

Answer 30

Phenomenon that may enable a portion of the graft overlying relatively avascular portion of the wound to revascularize

Capillaries enter the portion of the graft overlying the avascular portion of the wound from the relative highly vascular aspect of the surrounding recipient bed to create vascular bridges across the avascular portion of the wound

Full thickness grafts bridge better because collateral circulation within the dermis of a full thickness graft is less interrupted

Question 31

Describe graft contraction

Answer 31

After harvested grafts immediately shrink because of recoil of elastic fibers within the deep dermal layers known as primary contraction with a greater effect in full thickness grafts

Grafts composed solely of epidermis do not shrink at all

Skin graft inhibit wound contraction by accelerating the life cycle of the myofibroblast within the wound

Total percentage of dermis grafted is more important than the absolute thickness of the skin graft in preventing wound contraction

Question 32

reason for a graft failure

Answer 32

Fluid accumulation beneath the graft, movement, and infection

Most frequently because of infection

Question 33

Discuss graft failure by infection

Answer 33

Survival of the skin graft is better correlated to the concentration of bacteria in the recipient bed than to any other single factor, more than 10⁵ bacteria per gram of tissue the wound should not be grafted

Type of bacteria seems to be as significant if not more as the concentration of bacteria

Concentration of some bacteria most notably β-hemolytic streptococci and pseudomonas spp require less than 10⁵ per gram of tissue

β-hemolytic streptococci produce proteolytic enzymes, including streptokinase and staphylokinase that are destructive to both the graft and its recipient, destabilizing the fibrin network between the graft and recipient bed by catalyzing the conversion of plasminogen to plasmin which digest fibrin

Pseudomonas produce elastase which specifically degrades elastin in the dermis of the graft to which fibrin attaches

Question 34

Describe the preparation of full thickness sheet grafting

Answer 34

Suitable sites include cranial pectoral region where the skin is relatively mobile

Graft should be cut slightly larger than the recipient bed

Subcutaneous tissue should be removed to expose the dermis and its vasculature

Fascia and fat should be sharply dissected

Should be attached to the recipient site with slight tension to keep the small dermal vessels open for inosculation

Provide the best cosmetic appearance but are not as readily accepted as split thickness grafts

Usually reserved for fresh uncontaminated wounds

Question 35

Discuss split-thickness sheet grafting

Answer 35

Composed of epidermis and portion of the dermis and thickness is determined by the relative amount rather than the absolute amount of dermis included in the graft

Harvested by free hand knife, drum dermatome or power driven dermatome

Question 36

Discuss split-thickness graft harvesting

Answer 36

Watson grafting knife harvest a graft 100 mm (4 inches) wide

Drum dermatome allows harvesting a graft of the exact dimension to fit the wound

Power-driven dermatomes provide precision harvesting, the widest graft is only 76 mm (3 inches)

Question 37

Explain meshing sheet graft

Answer 37

Split or full thickness sheet graft can be applied to a recipient bed as solid or as meshed sheet, primary reason for meshing is to allow the graft to uniformly cover a wound larger than the graft itself, also to prevent blood or exudate from mechanically disrupting a newly applied graft from it delicate fibrinous and vascular attachments

Fenestrations in the graft fill with fibrin increasing graft stability

Question 38

Explain some considerations of expanded meshed graft

Answer 38

Each portion of the wound exposed within the fenestrations must heal by contraction and epithelization

The epithelium that eventually covers the expanded fenestrations has no adnexa, causing the wound to heal with abundant diamond-shaped epithelial scar

Size of epithelial scar can be reduced by attaching the graft to the wound so that the fenestrations within the graft are parallel with the skin lines

Question 39

Discuss graft acceptance and cosmesis

Answer 39

Thickness of the graft greatly influences its acceptance, the thinner the graft the less its metabolic needs and less its vascularity demands conversely the thinner the graft the poorer its durability and cosmetic appearance

Question 40

Describe island grafts

Answer 40

Small pieces of full thickness or split thickness skin placed either into or onto a granulating wound, the purpose of island grafts is to increase the area of epidermis from which epithelization can proceed

Island grafts heal primarily by epithelization

Types include pinch, punch, and tunnel grafts

Question 41

Describe punch grafts

Answer 41

Small full thickness plugs of skin that are harvested and implanted into granulation tissue using skin biopsy punches

Common donor sites are the ventrolateral aspect of the abdomen, perineum and portion of the neck that lies beneath the mane

Should be harvested in a symmetrical pattern about 1 cm apart

Subcutaneous fascia and fat should be sharply excised

Recipient holes in the granulation tissue should be created before the graft are harvested to allow hemostasis, the depth of the recipient holes should correspond to the thickness of the graft and should be placed about 6 mm apart in a symmetrical pattern

Holes should be slightly smaller to allow contraction of the graft

Usually reserved for small wounds where cosmesis is not important

Survival of 60% to 75%

Question 42

Describe pinch grafts

Answer 42

Small disc of skin harvested by excising an elevated cone of skin that laid onto or implanted into granulation tissue sometimes referred as Reverdin grafts

A disc of optimal size is approximately 3 mm in diameter which approaches full thickness toward the center but its thickness diminishes toward the periphery

A cone of skin is elevated and excised

To implant a No 15 scalpel blade is stabbed into the granulation tissue at an acute angle to create a shallow pocket into which the graft is inserted about 3-5 mm apart epidermal side up proximal to the pocket

50% to 75% survival

Question 43

Discuss tunnel grafts

Answer 43

Strips of split-thickness or full thickness skin implanted into tunnels created in granulation tissue

The graft are exposed days later when the have revascularize by excising the overlying granulation tissue

To implant, a long thin rat-tooth alligator forceps is inserted into the granulation tissue and advance at a depth of 5-6 mm until emerges on the opposite side to grab and pull the strip of skin through

Graft should be embedded at a right angles to the convex surface of the wound to aid entry and exit of the forceps, strips should be embedded 2 cm apart

6-10 days the roof of each tunnel is removed

60%-80% survival

Question 44

Discuss graft storage

Answer 44

McCoy’s 5A medium is a tissue culture medium composed of balanced electrolyte solution to which amino acids, vitamins, dextrose, and pH indicator (phenol red) have been added

Split thickness king graft refrigerated at 4⁰ C in McCoy’s 5A medium and horse serum can be successfully stored for 3 weeks

Concentration of serum in the storage medium should be 10%-33%

A color change in the McCoy’s 5A medium from cherry-red to orange-yellow indicates excessive accumulation of catabolites and need immediate application of the graft or replacement of the medium

Question 45

1. Describe the layers of the epidermis

Answer 45

Composed of 4 layers- stratum Basale, S. spinosum, S. Granulosum, S. corneum

Stratum corneum slows water loss and functions as a barrier to harmful substances

Question 46

Describe debridement

Answer 46

Effective way to reduce bacterial load within the wound and minimize necrotic tissue

Debridement is used to alter the wound classification from infected to contaminated to clean to clean contaminated to clean

Most common types include sharp, mechanical, chemical, biological, and autolytic

Sharp and autolytic should be primarily use in equine wound care

Question 47

Discuss wet-to-wet and wet-to-dry dressings

Answer 47

Wet-to-wet are intended to stay wet and may have to be remoistened up to six times a day much more effective at removing necrotic tissue than using gauze while causing less damage to the fibroblast and epithelial cells

Wet-to-dry performed by moistening the primary dressing (dressing against the wound bed) while leave the rest of the dressing dry, primary dressing should never be allowed to dry as this reduces effectiveness of autolytic debridement

Question 48

1. Discuss chemical and enzyme debridement

Answer 48

Chemical debridement has been used in many different forms in wound care and example includes Dakin’s solution (diluted bleach), hydrogen peroxide, acetic acid, and hypertonic saline

This debridement is nonselective and should be reserved for very contaminated wounds

Enzymatic debridement involves placing enzymes directly onto the wound bed

Most commonly used enzymes are streptokinase/streptodornase, collagenase, DNase/fibrinolysin, papain/urea, and trypsin

Enzymatic debridement is limited when large amount of necrotic tissue have to be removed and should be used after an initial sharp debridement

Question 49

List the options for wound closure

Answer 49

Primary closure, delayed primary closure, and second intention healing

Question 50

List the stages of wound healing

Answer 50

Inflammatory/cellular reaction stage

Debridement stage

Tissue formation/proliferation stage

Maturation/remodeling stage

Question 51

Describe wound classification

Answer 51

Classified on the basis of degree of contamination

Clean wounds, clean contaminated, contaminated, infected

Color evaluation RYB color code

R= fresh or red and indicates granulation tissue

Y=yellow and indicates purulent debris

B=black and indicate necrotic tissue

P and G sometimes are added and indicate epithelialization and gangrenous tissue

Question 52

Describe delayed primary closure

Answer 52

Wound is initially treated openly to allow debridement and reduce bacterial contamination followed by primary closure

Reserved for wounds that have mild to moderate bacterial contamination, minimal tissue loss, and minimal tension

Very useful in the management of abdominal incisions

Wounds should be debrided and cleaned to reduce bacterial burden

Question 53

Describe hypertonic saline dressing

Answer 53

Curasalt, 20% hypertonic saline on kerlix gauze for the use on necrotic or heavily exudating wounds

Works by osmotic action to remove necrotic tissue and bacteria

Nonselective chemical debridement, dressing should be changed every 24-48 hours at the beginning of the treatment

Question 54

Discuss growth factors

Answer 54

Benefit of platelet-derived growth factor (PDGF) decreases wound healing time

Acts a chemotactic agent and mitogen for fibroblasts, smooth muscle cells and inflammatory cells

Transforming growth factor-β (TGF-β) has a profibrotic function in wound healing in that it seems to encourage formation of granulation tissue

Question 55

Discuss negative pressure wound therapy

Answer 55

Beneficial in both acute and chronic wounds

Possible benefit include increased blood flow, increased angiogenesis, increased rate of granulation tissue formation increased flap survival and decreased bacterial number and edema formation

Question 56

Describe the ways to address possible pneumothorax

Answer 56

Placement of a chest tube

Teat cannula can be attached to a 60 ml syringe with a three-way stopcock to remove air from the chest cavity, cannula should be placed in the upper third of the chest to enable removal of the large volume of air

Question 57

Discuss wounds to the abdominal cavity

Answer 57

Diagnostic challenge due to the numerous layers that vary depending on the location

Aseptic technique should always be used

All tissue planes should be examined

Abdominocentesis may help but in many cases the TP and cell count are within normal limits

If the peritoneal cavity has been entered abdominal exploratory is granted

Question 58

Discuss axillary lacerations

Answer 58

Often present subcutaneous emphysema that is created when the horse moves its leg forward opening the wound and filling it with air, in some cases a pneumomediatinum occurs which can lead to pneumothorax

Question 59

Describe the differences between a sinus tract and a fistula

Answer 59

Fistula is an abnormal passage or communication, usually between two internal organs or leading from an organ to the surface of the body

Sinus tract is defined as a cavity or channel it may be normal or pathologic

Question 60

Discuss sinus tract exploration

Answer 60

Exploration is carried out with a malleable probe and groove director

Infusion of a vital dye such Evan’s blue further facilitates recognition of the tract during surgery

After foreign body removal all linings of the sinus tract should be curetted so that most of the bacterial contamination is removed

Tract should be flushed with sterile saline

Usually better to simply debride the cloaca rather than to close it

Question 61

Discuss special considerations for chronic sinus tract

Answer 61

Location may indicate that the tract did not develop secondary to a foreign body

Sinus tract in the head a dental problem should be suspected

Near the base of the ear is usually the result of a choanal cyst (ear tooth)

Over the pole or withers region may indicate a development of an infected bursa in this area called pole evil and fistulous withers (Brucella)

Question 62

Discuss sarcoids

Answer 62

Most common tumor in the horse, is a cutaneous fibroblastic neoplasia with proliferative epithelial component

Classified histopathologically as benign tumors because of the morphologic characteristics of the fibroblasts and because many sarcoids are slow growing and cause little if any physical problem (misleading)

Question 63

sarcoid subtypes based on clinical appearance

Answer 63

Occult

Verrucous

Nodular fibroblastic

Ulcerative fibroblastic

Mixed tumors

Malevolent (most aggressive)

Question 64

etiology of sarcoids

Answer 64

QH and related stock breeds are twice as likely to develop sarcoids and TBH

Direct genetic linkage has been reported between equine leukocyte antigen (ELA) and risk for equine sarcoid

ELA alleles A3 and W13 were strongly associated with risk for sarcoids in TBH and Swiss French and Irish warmblood

The genetic predisposition for and age of onset of sarcoids suggest that both genetic and exogenous factors may play a role in development

Presence of bovine papilloma virus (BPV) DNA in nearly all equine sarcoid tissues examined

Question 65

sarcoid treatment

Answer 65

Sarcoids can transform to a more aggressive phenotype after incomplete or unsuccessful treatment and are the harder to resolve

Options include surgical excision (15.8%-82%0, laser ablation (38%), cryotherapy (91%), hyperthermia, radiotherapy, immunotherapy (0%-40%), intralesional cisplatin,

Question 66

Discuss squamous cell carcinoma

Answer 66

Malignant locally invasive neoplasia of squamous epithelial cells

Second most common tumor in horses

Sites of predilection include areas lacking pigmentation, poorly haired regions and skin near mucucutaneous junctions

Should be considered in horses with chronic refractory hoof abscess

SCC typically spreads to surrounding tissues and local lymph nodes

Question 67

treatment for SCC

Answer 67

Surgical excision, radiation, topical application of antimitotic, intralesional chemotherapy, cryotherapy, laser excision, hyperthermia, immunotherapy, and photodynamic therapy

Question 68

Discuss irradiation treatment for SCC

Answer 68

External beam radiotherapy, implanted radiation devices, and b-emitting wands

Strontium wands (b-radiation) can be used to treat small superficial plaques on the cornea sclera or conjunctiva

Question 69

Describe melanomas

Answer 69

Melanomas account for 4%-15% of all skin tumors

Majority occur in gray horses

Progression from melanocyte accumulation to melanoma formation has been documented in melanoma prone locations

Question 70

types of melanomas

Answer 70

Melanocytic nevi composed of larger pleomorphic melanocytes with an increased number of mitotic figures, binucleate cells and variable cytoplasmic pigmentation

Dermal melanomas appear benign on histopathology and are composed of smaller homogenous dendritic cells with condensed chromatin, dense pigmentation and no visible mitosis

Dermal melanomatosis same as dermal melanomas

Malignant melanomas rare and are classified on the basis of the presence of both histopathologic and clinical characteristics of malignancy and frequently invasive and associated with poor prognosis for complete resolution

Question 71

treatment for melanomas

Answer 71

Dermal melanomas and melanocytic nevi have similar characteristics and surgical excision is curative in the majority of cases

Complete excision is difficult with large lesions such as dermal melanomatosis but surgical debulking can be palliative

Oral cimetidine has been recommended because its antitumor activity and is a histamine receptor agonist, immunomodulation of lymphocyte activity via histamine receptor interaction is postulated as a mechanism of antitumor activity 2.5 mg/kg Q-8

Additional treatment include intralesional chemotherapy and cryotherapy

Question 72

Discuss mast cell tumors

Answer 72

Equine cutaneous mastocytosis (ECM) less common in horses

Benign solitary nodular cutaneous form is the most common, although malignant ECM and congenital disseminated form have been recognized

Release of inflammatory products from accumulated eosinophils and mast cells result in necrosis and later granulomatous reaction develops with fibrosis and subsequent encapsulation of the nodule

Question 73

Discuss cutaneous habronemiasis

Answer 73

Proliferative ulcerative lesion produced by aberrant migration of larvae of three endoparasites (Habronema muscae, Habronema microstoma, and Draschia megastoma)

Cutaneous form all called summer sores develop when larvae are attached to wound beds or aberrant moist surfaces, including the penis, prepuce, and ocular adnexa

Histopathologic examination is recommended because habronemiasis can develop secondary to an underlying neoplastic of infectious condition

Question 74

habronemiasis treatment

Answer 74

Treatment is aimed at reducing the size of the lesions resolving the inflammatory or allergic component and preventing reinfestation

Topical preparation that combine organophosphates, corticosteroids, DMSO and nitrofurazone have been used

Question 75

Discuss pythiosis

Answer 75

Cutaneous disease caused by invasion of the organism Pythium insidiosum a fungus-like oomycete, occurs principally in warm tropical regions

Infection happens by invasion through small wounds or skin breaks typically in lakes swamps or flooded lands

Pruritic; sinus tracts are visible and often contain gritty coral like masses called kunker or leeches

Pythiosis occur most often in the distal extremities and ventral body wall

Question 76

treatment for pythiosis

Answer 76

Surgical excision is the treatment of choice

Systemic, topical and intralesional antifungals have been used but recurrence is common

Question 77

Discuss papillomatosis

Answer 77

Papillomaviruses are Very host- and tissue-specific and are the causative agents of most warts seen in mammals

Equine papillomatosis and aural plaques are caused by equine papillomaviruses (EqPV)

Infect the basal layer of the epidermis resulting in an abnormal proliferation and hyperkeratosis of the epithelium

Question 78

Discuss dentigerous cyst

Answer 78

Congenital defect, it arises as a result of incomplete closure of the first brachial cleft during embryologic development

Contain dental elements, such as enamel dentin and cementum

The epidermal lining differentiates as does normal epidermis and the cyst becomes nodular as it begins to fill with keratin

Typically, unilateral swelling at the base of the ear but can occur in other locations on the head and sinus

Question 79

treatment for dentigerous cyst

Answer 79

If desire surgical excision with complete extirpation of the cyst lining is necessary to prevent recurrence

The plane of dissection should be closed to the wall of the cyst as possible to prevent damage to the auriculopalpebral nerve and auricular muscles as well as to minimize hemorrhage