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Pod Med II > Skin Analysis Techniques > Flashcards

Skin Analysis Techniques Flashcards

1
Q

Calciphylaxis

A
  • Disease in which calcium accumulates in small blood vessels of the fat and skin tissues
  • Causes blood clots, painful skin ulcers and may cause serious infections that can lead to death
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2
Q

People who have calciphylaxis usually have

A
  • Kidney failure and are on dialysis or have had a kidney transplant
  • Condition can also occur in people without kidney disease
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3
Q

Mimics of cellulitis

A
  • Stasis dermatitis (acute)
  • Lipodermatosclerosis
  • Contact dermatitis
  • Dermatohypersensitivity reaction
  • Lymphedema
  • Gout
  • Erythema migrans
  • Cryptococcal cellulitis
  • Calciphylaxis
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4
Q

Dermatoscope

A
  • Handheld magnifying device (typically 10×) which uses an oil medium or cross-polarised light allowing the viewer to observe structures deeper in the skin, not normally visible to the naked eye
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5
Q

Dermatitis Tx option

A
  • Pharmacological
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6
Q

Neoplasm Tx option

A
  • Surgical excision
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7
Q

Ideally, you should biopsy

A
  • Any inflammatory lower extremity disorder with a questionable diagnosis
  • Any blistering “rash”
  • Any suspicious neoplasm
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8
Q

Common biopsy techniques

A
  • Punch biopsy
  • Shave biopsy
  • Saucerization (a form of shave biopsy)
  • Curettage
  • Core needle
  • Aspiration biopsy
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9
Q

Choosing which biopsy technique to use

A
  • In general terms, when a small part of a patch or plaque is sampled for histopathology, a punch biopsy is the technique of choice
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10
Q

General biopsy rule

A
  • Only large lesions are punched

- Small are shaven

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11
Q

Verrucous lesions on plantar surface

A
  • Tend to by endophytic (grows inward)
  • Shave biopsy may not sample deep enough to obtain diagnostic info
  • Punch biopsy better to distinguish lesions that may mimic each other
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12
Q

A punch biopsy is a common technique used to sample conditions that

A
  • Are too large to be shaven

- Have a deep dermal component (requiring deeper sampling)

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13
Q

Punches may be used to sample

A
  • Suspected vasculitis
  • Ulcers
  • Large pigmented lesions (those too large to be shaven)
  • Other large suspected neoplasms (those that are greater than 1cm in diameter)
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14
Q

3-millimeter punches are used for

A
  • Epidermal nerve fiber density testing
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15
Q

Small punches (2mm) are ideal for

A
  • Plantar verrucous lesions
  • Because this technique samples the full thickness of such plantar lesions, it allows Dermatopathologists to accurately discriminate between genuine verrucae and clinically identical verrucous carcinomas
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16
Q

In summary, punch biopsies are ideal when

A
  • A small part of a much larger lesion is submitted for histopathology
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17
Q

Standard shave biopsies

A
  • Used more commonly in dermatologic practices than punch biopsies
  • Combination of standard shaves and saucerizations represents the overwhelming majority of biopsies performed by dermatologists
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18
Q

Shaves do not routinely sample the deep dermis

A
  • They typically extend only to the depth of the superficial dermis
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19
Q

Always make sure pt has _____ before punch biopsy

A
  • Arterial perfusion
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20
Q

Where punches are relatively narrow (most punches are 2-4mm in diameter), shaves often encompass

A
  • A broad sample of superficial skin (often 1cm or greater in width)
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21
Q

Shave technique is the ideal sampling method for

A
  • Unexplained papules (elevated lesions measuring 5mm or less in diameter)
  • Can be used for macules (flat lesions measuring less than 1cm in diameter)
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22
Q

Saucerization

A
  • Closely related to a standard shave biopsy
  • Uses a bendable blade, not dissimilar to a Gillette razor blade, to “scoop out” the tissue of concern
  • Better for flat or endophytic (inward growing) lesions
  • More aggressive, can be considered more of an excision
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23
Q

Curettage

A
  • Less common sampling method

- Uses a dermal curette to scrape the surface of the skin to obtain the desired tissue sample

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24
Q

Curettage disadvantage

A
  • Specimens may be difficult to histopathologically examine
  • Inherent fragmentation of the sample
  • May make the tissue impossible to correctly orient
  • Used with non-healing wounds
25
Q

Core needle biopsy

A
  • ideal method of diagnosing more deeply seated masses
  • Perfect for investigating tumors of the soft tissue
  • Essentially any mass that falls into the differential diagnosis with a lipoma or ganglion could be sampled using core needle technique
26
Q

Core needles

A
  • Hollow large gauge needles designed to withdraw thin columns of tissue from within the mass in question
27
Q

To obtain tissue using core needle biopsy

A
  • The skin overlying the mass is incised and the instrument is inserted to abut the mass in question
28
Q

Core needle mechanism

A
  • Depending on the size of the mass, the biopsy instrument is set by the clinician to sample to a desired depth using a spring loaded mechanism
  • The device is discharged and the sample is obtained
  • This is usually repeated into the masses’ various quadrants
29
Q

Needle aspiration biopsy

A
  • Underutilized diagnostic procedures of those available
  • May be effectively used to rule out high‐grade malignancies when faced with nonspecific subcutaneous masses (in particular, those masses that resemble ganglion cysts)
30
Q

Neoplasms masquerading as ganglion cysts may fool clinicians

A
  • Roughly 70% of all the soft tissue masses in the foot are ganglia
31
Q

Needle aspiration differs somewhat from most other biopsy techniques in that

A
  • It provides the pathologist with cells and tiny tissue fragments to review, rather than large pieces of tissue
  • Cytopathology can be somewhat less specific than histopathology
32
Q

The pathology reports derived from aspiration specimens typically provide

A
  • Basic, though highly significant information

- “malignant cells not identified”, “atypical cells identified”, or “malignant cells identified

33
Q

Practice guidelines have recommended performingwound biopsiesfor histological diagnosis or microbiologic testing inwoundsthat havenotimproved within

A
  • 3 to 6 weeks of appropriate management
34
Q

If a wound you are seeing for the first time exhibits clinical signs of malignancy (ABCDE)

A
  • Asymmetry
  • Irregular border
  • Color variation
  • Diameter
  • Evolving
  • Biopsy immediately (if not, treat based on presumed etiology)
35
Q

Diagnosis onychomycosis

A
  • Can be confirmed by direct microscopic examination with a Potassium Hydroxide (KOH) wet-mount preparation
  • Histopathologic examination of the trimmed affected nail plate with a Periodic-Acid-Schiff (PAS) stain
  • Fungal culture
  • PCR assays
36
Q

Ideal test for diagnosing onychomycosis would

A
  • Identify the fungus and the species
  • Determine its viability
  • Be easy to perform with rapid result and low cost
  • Be highly specific and sensitive
37
Q

Woods light

A
  • Helps to differentiate between interdigital erythrasma and Tinea pedis
38
Q

Erythrasma

A
  • Superficial skin infection cause byCorynebacterium minutissimum
39
Q

Erythrasma most commonly affects

A
  • Plantar feet and interdigital areas
  • Most common cause of interdigital bacterial infection on the feet
  • Most often visible between the fourth and fifth toes
40
Q

Interdigital erythrasma

A
  • More difficult to diagnose as the web spaces become macerated
  • Common to see concurrent infections with a bacteria and dermatophyte
41
Q

Interdigital erythrasma differential diagnosis

A
  • Psoriasis
  • Dermatophytosis
  • Candidiasis
  • Intertrigo
42
Q

Tx of erythrasma

A
  • Typically begins with topical agents

- Research has shown that related species ofCorynebacteriumare sensitive to topical clindamycin

43
Q

Erythrasma Tx schedule

A
  • Applying topical clindamycin 1% gel or cream to the affected area two to three times a day for two to four weeks effectively eradicates most infections
  • Alternative topical treatments include erythromycin 2% gel and Whitfield’s ointment
44
Q

Key elements of wound infection

A
  • Occurs in wound tissue, not on the surface of the wound bed
  • Occurs in viable wound tissue; it isn’t a phenomenon of necrotic tissue, eschar, or other debris contained in the wound bed
  • Caused by invasion and multiplication of microbes in the wound
  • Manifested by a host reaction or tissue injury
45
Q

Three techniques that can be used to identify colonization or infection

A
  • Deep tissue or punch biopsy
  • Needle aspiration
  • Swab culture
46
Q

Swab culture technique

A
  • Most commonly used because it is practical, simple, noninvasive and cost effective
47
Q

Swab culture of a chronic wound may not identify

A
  • All types of microbes
  • Does not identify any microbial load in the deep tissue
  • May only identify surface bacteria
48
Q

Gold standard in identifying bacteria in the wound bed

A
  • Wound biopsy sent for culture and sensitivity testing
49
Q

Methods of swab culture

A
  • Z stroke technique

- Levine’s technique

50
Q

Z stroke technique disadvantages

A
  • Less optimal

- Likely to pick up organism from necrotic tissue if present, skin edges

51
Q

Z stroke technique

A
  • Swab should be rotated between the fingers as the wound is swabbed from margin to margin in a 10-point, zigzag fashion
  • Because a large portion of the wound surface is sampled, the specimen collected may reflect surface contamination rather than tissue bioburden.
52
Q

Levine’s technique

A
  • Surface swab of a once cm^2 area of healthy tissue in the wound
  • Press into wound to obtain fluid
53
Q

Levine technique methods

A
  • Swab is rotated over a 1-cm square area with sufficient pressure to express fluid from within the wound tissue
  • Believed to be more reflective of tissue bioburden than swabs of exudate or swabs taken with a broad Z-stroke
54
Q

Theoretically, the Levine technique is the best technique for wound swabbing, provided

A
  • The wound is cleansed first

- The area sampled is over viable tissue, not necrotic tissue or eschar

55
Q

The swab technique most consistent with the key elements of wound infection is

A
  • Levine’s technique

- Attempts to sample microorganisms from within the wound tissue, not just from the wound surface

56
Q

Molecular methods advantages over agar cultures

A
  • Accuracy
  • Rapid results
  • High sensitivity
  • High benefit to expense ratio, specificity and availability
  • Quantitative
57
Q

Molecular methods are singularly suited to diagnose

A
  • Polymicrobial and biofilm associated clinical infections
58
Q

Polymerase chain reaction (PCR)

A
  • Molecular technique utilized to target and “amplify” a single or few copies of a piece of DNA, generating thousands to millions of copies of a particular DNA sequence thereby allowing them to be detected
59
Q

PCR benefits

A
  • Bacteria are identified by “amplifying” their DNA, requiring only a tiny sample, without actually having to grow bacterial cultures in the microbiology laboratory
  • This technology is sensitive, specific and can be done in hours

Pod Med II (3 decks)

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