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General Surgery > Part twos - skin > Flashcards

Part twos - skin Flashcards

1
Q

What is necrostising fasciitis

A

A necrotising soft tissue infection of the deeper tissues that results in progressive destruction of the muscle fascia and overlying subcutaneous fat.

Muscle tissue is frequently spared because of its generous blood supply.

Infection typically spreads along the muscle fascia due to its relatively poor blood supply.

Initially the overlying tissue can appear unaffected. It is this feature that makes necrotizing fasciitis difficult to diagnose without surgical intervention.

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2
Q

What is Fournier’s gangrene?

A

Necrotising soft tissue infection of the perineum

Initially described in men only but does no include women.

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3
Q

Risk factors for necrotising soft tissue infections

A 
DIabetes 
Immunocompromise - HIV
Obesity
PVD
CRF
Alcohol and IVD abuse
Trauma - surgery, bites
IDUC
Chicken pox, vesicles
GIT perforation 0 rare
Abscess
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4
Q

Pathophysiology of necrotising soft tissue infection

A

Microbial invasion of subcutaneous tissue

Tracking of bacterial through subcutaneous tissues producing endo- and exotoxins causing - ischaemia, liquefactive necrosis, systemic illness

Various bacteria-associated toxins stimulate CD4 cells and macrophages to produce TNF-alpha, IL-1 and IL-6 -> SIRS -> septic shock -> MOD -> death

Final common pathway is tissue ischaemia

Key feature = thrombosis of perforating vessels to the skin due to:

  • hypercoagulable state
  • platelet-neutrophil plugging of vessels
  • increased interstitial pressure
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5
Q

How are necrotising soft tissue infections classified?

A
  1. By location
  2. By depth
  3. By microbial cause
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6
Q

How are necrotising soft tissue infections classified by location?

A

Ludwig’s angina - floor of the mouth

Fournier’s gangrene - perineum

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7
Q

How are necrotising soft tissue infections classified by depth?

A

Cellulitis
Adipositis/panniculitis
Fasciitis
Myositis

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8
Q

How are necrotising soft tissue infections classified by micro-organism?

A

Type 1 - polymicrobial - most common
Type 2 - monomicrobial
Type 3 - Vibrio vulnificus

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9
Q

Structure of skin

A 
Epidermis
--Stratum corneum
--Stratum granulosum
--Stratum spinosum
--Stratum basale
Dermis
--Papillary dermis
--Reticular dermis
Subcutis
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10
Q

What are are eccrine sweat glands (regular sweat gland)?

A

Skin appendage situated on skin everywhere that synthesises sweat

  • predominance on palms, soles, face
  • located at junction between dermis and subcutis
  • SNS cholinergic supply
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11
Q

What are apocrine glands?

A

Skin appendage that is a modified sweat gland found in the axilla and groin

  • secretory component in reticular dermis or subcutis
  • duct carries secretion to be discharged above sebaceous duct in upper hair follicle
  • no definite function in humans, scent in animals
  • SNS adrenergic supply
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12
Q

What are sebaceous glands?

A

Skin appendage that secrete sebum (lipid mixture) into hair follicle o provide waterproofing

  • areola, nipples, labia minora, eyelids, buccal, labial mucosal glands are independent of hair follicles and open directly onto skin or mucosa
  • no motor innervation
  • acted on by androgens
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13
Q

What is subcutaneous tissue?

A

Areolar tissue connecting skin to underlying bones or deep fascia by fibrous bands.

Contains fat, nerves, blood vessels and lymphatics that pass to the skin

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14
Q

What is deep fascia?

A

Membrane of fibrous tissue wrapping limbs and body wall

Varies in thickness:

  • thick in limbs
  • scarcely semonstartable over lower thorax and abdomen
  • absent in face and ischioanal fossa
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15
Q

What is melanoma?

A

Malignant neoplasm of melanocytes which is aggressive and can spread in an unpredictable manner to involve virtually any organ

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16
Q

Melanocytic naevus

A

Any congenital or acquired neoplasm of melanocytes

  • Congenital nevus
  • Blue nevus
  • Spindle and epithelial cell nevus (Spitz nevus)
  • Halo nevus
  • Dysplastic nevus
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17
Q

Borders of the submandibular triangle

A

Anterior belly digastric muscle
Posterior belly digastric muscle
Inferior border of mandible

18
Q

Fight bite microbiology

A

Typical polymicrobial oral flora:

  • Eikenella corrodens (GNB) 30%
  • Staphylococcus aureus 30%
  • Streptococcus
  • Corynebacterium species
  • Bacteriodes (anerobe)
  • Peptostreptococcus (anaerobe)
19
Q

Dog bite microbiology

Cat bites similar

A

Polymicrobial with animal oral flora, recipient skin flora and environmental organisms:

  • Pasteurella species
  • Staphylococcus
  • Streptococcus
  • Capnocytophaga canimorsus (GNB)
20
Q

Define keratocanthoma

A

Cutaneous tumour most commonly presenting as a dome-shaped nodule with a central keratin-filled crater

21
Q

What is Hutchinson sign?

A

Extension of pigment to the proximal or lateral nail fold or free edge of nail plate in nail melanoma

22
Q

What is Mohs micrographic surgery?

A

Specialised surgical procedure combining staged resection with comprehensive surgical margin examination resulting in high cure rates for even high-risk lesions together with maximal preservation of normal tissues

23
Q

What is a rodent ulcer?

A

A centrally ulcerated nodular BCC

24
Q

Types of BCC

A 
Nodular - 60%
Superficial - 30%
Morphoeic - 5%
Pigmented
Basosquamous

because (BCC) No Sex Makes People Bad

25
Q

BCC excision margin

A

5mm ideally
10mm for morphoeic/sclerosing and recurrence
often satisfied with 2mm on the face
0.5mm microscopically acceptable

26
Q

Macroscopic features of BCC

A 
Translucent elevated nodules
Pearly rolled edges
Telegectasia
\+/- ulceration
\+/- pigmentation
27
Q

High risk factors for BCC

A
  • Large size
    • Situated central face - eyes, nose, lips, ears
    • Poorly defined lesions
    • Certain types - morphoeic, micro-nodular, basosquamous
    • Perineural and/or perivascular invasion
    • Recurrence
    • Immunosuppression
28
Q

What is a Marjolin ulcer?

A

SCC occurring in a burn scar -> aggressive with poor prognosis

29
Q

Follow-up points about BCC

A

45% will develop another BCC within 3 years so require education and regular skin checks.

Only 40% of those incompletely excised will recur within 5 years

30
Q

What is SCC?

A

Carcinoma arising from keratinocytes

Carcinoma of the epidermal cells forming the superficial keratinous squamous layer

31
Q

What is BCC?

A

Carcinoma arising from the basal layer of the epidermis

32
Q

How is a lymphoscintogram performed

A

Hours prior to surgery, a sulphur colloid tagged with Tc-99m is injected peritumourally and scintigraphic imaging is performed at 10 and 60 minutes.

A gamma probe and blue dye is used intra-operatively to identify the mapped sentinel node(s).

33
Q

What is Breslow thickness?

A

Depth measured in mm from the granular layer of the epidermis to the point of deepest invasion in malignant melanoma.

The main indicator for prognosis.

34
Q

How is melanoma staged?

A

AJCC TNM system
Tis = in situ (within epidermis)
T1 4.0 mm
a) absence or b) presence of ulceration

N1 = 1 L
N2 = 2-3 or in-transit mets with no LN mets
N3 = 4+
a) micro b) micro

M1a = skin, subcutis, distant LN, normal LDH
M1b = lung, normal LDH
M1c = visceral mets or any mets with abnormal LDH

Stage I = T1, T2a - 85-100% 5YS
Stage II = T2b-T4 - 40-85%
Stage III = nodal disease - 25-60%
Stage IV = metastatic disease - 15%

35
Q

What are the most important prognostic indicators for melanoma?

A

Breslow thickness
Presence of ulceration
Mitotic rate
NODAL DISEASE

36
Q

WLE margins for melanoma

A

Tis - 5mm
T1 - 1cm
T2 - 1-2cm
T3+ - 2cm

37
Q

Risk of lymph node metastasis based on Bresow thickness

A

<0.75mm - rare
0.75-1.0mm - 5%
1-4mm - up to 30%
4mm - 40%+

38
Q

Clark’s levels

A

Outdated except when tumours < 1mm where they still retain their prognostic significance

I - confined to epidermis / melanoma in situ / above BM
II - Invasion into papillary dermis
III - Filling papillary dermis
IV - Invasion into reticular dermis
V - Invasion into subcutaneous fat
39
Q

MSLT1

A

n=1661, tumours 1+mm or Clark IV or V - 2cm margins
SLNBx +/- CLND vs Observation + CLND if clinical disease
No melanoma-specific survival benefit
DF10YS benefit for SLNB for tumours 1.2mm+
SLNB gives prognostic info to patient

In tumours 1.2-3.5mm and node positive, there was MS10YS benefit as well as DF10YS benefit

40
Q

Xeroderma pigmentosum

A 
Autosomal recessive
Deficient repair of DNA damage due to UV radiation.
NER genes mutated
1000x BCC/SCC/MM
<40% live beyond 20 years
Most die from metastatic SCC/melanoma
41
Q

Immunohistochemistry for melanoma

A

S100
HMB-45
Melan-A
Ki-67

General Surgery (25 decks)

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