introduction to dermatopathology
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Introduction to DermatopathologyTRANSCRIPT
Introduction to Dermatopathology
Peter Pavlidakey, MD
Definition of Dermatopathology
• Subspecialty of dermatology and pathology focused on performing and interpreting tests on human tissue samples to provide scientific data and consultative opinions to referring clinicians
• Interpretation of skin biopsies
Dermatopathology thought process
• Clinical problem
• Biopsy planning
• Biopsy technique
When to perform a skin biopsy
• What can a skin biopsy tell us?
• What are the limitations?
• How do these limitations apply to the clinical scenario?
When to perform a skin biopsy
• When is a skin biopsy most likely to be fruitful?
– When it is performed to investigate a focused hypothesis
Example: biopsy for alopecia
• Why is she losing her hair?
• Is the etiology of this patient’s hair loss lupus erythematosus or lichen planopilaris?
Example: Dermatitis
• Why is this patient’s rash not responding to therapy
• Biopsy out of need
• Is our presumed clinical diagnosis correct or are we in fact dealing with another process?
• Prior therapy?
When is a biopsy least likely to yield useful information?
• The biopsy without a clinical hypothesis or in which the clinical hypothesis is not communicated to the dermatopathologist
Biopsy planning
• Where to biopsy
• How to biopsy
Where to biopsy
• Biopsy the area most likely to distinguish among the considerations or most likely to confirm the primary consideration.
Where to biopsy: NMSC
• Preferable to sample entire lesion
• Sample lesion and adjacent normal skin
• Sample entire deep edge of small lesions
Best
Better
Worst
Good
Where to biopsy: Rash
• Sample border of process and unaffected skin
• Different morphologies? – Consider multiple samples
• Prefer new lesions for most conditions –exceptions exist – no substitute for knowledge of process being sampled
Worst
BetterBest
Where to biopsy: Blister
Biopsy of pigmented lesions
• Dysplastic nevus vs melanoma: elipse, punch, or “scoop” shave – at least 1 mm!
• Try to avoid transecting lesion – peripheral or deep
• Shave-punch vs double shave
• What information will the surgeon and oncologist need?
Classification Thickness Ulceration/Mitosis
T1 ≤1.0 mm A: w/o ulceration and mitosis < 1/mm²B: with ulceration or mitosis ≥ 1/mm²
T2 1.01- 2.0 mm A: w/o ulcerationB: with ulceration
T3 2.01- 4.0 mm A: w/o ulcerationB: with ulceration
T4 >4.0 mm A: w/o ulcerationB: with ulceration
Melanoma Staging
Types of sampling
• Shave
• Punch
• Ellipse
• Curettage
• Extraction
• Fine needle aspiration
• Scraping
• Special sampling for hair and nail
Shave biopsy: definition
• Horizontally transects the epidermis
• Usually with a specialized flexible blade or small scalpel
• Deep shave often referred to as saucerizationor “scoop”
Shave biopsy: Advantages and limitations
• Breadth and depth can be tailored infinitely to the process being sampled
• Ideal for sampling processes restricted to the epidermis and superficial dermis
• Usually neoplasms
• Neoplastic conditions with findings restricted to the epidermis which can be sparse: mycosis fungoides, superficial EAC, PUPPP, etc.
• Potentially excellent cosmesis
Punch biopsy
• Uses a specialized cylindrical instrument to vertically transect all levels of the skin
• 1 mm to 1 cm
• Often used to sample dermatitis and selected neoplasms
Punch biopsy: Advantages and limitations
• Potentially samples all layers of the skin
• Much quicker than ellipse
• Variety of sizes available: balance sampling and cosmesis
• Potential to under sample and miss sparse findings
Punch biopsy: Tips and techniques
• Use the smallest size which will adequately sample the disease process
• Use 6 mm or larger to sample subcutis
• Never sample suspected panniculitis with 2 mm punch!
• >3 mm preferred to sample dermatitis
• Do not use crushing instruments to extract the sample
Ellipse
• Incision to subcutis
• Incisional or excisional
Ellipse: Advantages and limitations
• Greatest potential for one step management
• Excellent cosmesis with good technique and planning
• Least likely to yield false negative or uninformative result
If all else fails…
• Use shaves to sample neoplasms
• Use punches to sample rashes
• Consider elliptical excisional biopsy to sample when suspicion for malignancy is high.
Specimen labeling and handling
• Patient identifiers in duplicate
• Precise site designation in duplicate
• State the clinical hypothesis
• Indicate type of procedure and intent of procedure
• Indicate desire for margin evaluation
• Minimize requests of adjuvant diagnostic testing
Submit a clinical photo
Thank you
Dr Kim Hiatt Dr Peter Pavlidakey