Dermatopathology Flashcards
What is the pathological definition of basal cell carcinoma
A group of malignant cutaneous tumours characterised by the presence of lobules, columns, bands or cords of basaloid cells
* most slow growing and non-aggressive
Describe the histopathology of a basal cell carcinoma
- originate from follicular bulge stem cells and basaloid epithelia of follicular projections of anagen hair buds
- dual population of fibrous stroma and islands of basaloid cells
- peripheral palisading and haphazard arrangement of cells in centre of islands
- numerous mitoses and apoptotic bodies
What are the histopathological subtypes of basal cell carcinoma?
- nodular (less risk of recurrence)
- superficial
- infiltrative (less cohesive with disparate tumour islands/possible perineural infiltration, increased risk of recurrence)
What would you include in a pathological report for BCC?
- confirmation of diagnosis
- subtype of BCC
- whether there is perineural infiltration or not
- distance to margins
- pT staging
What is the definition of squamous cell carcinoma?
A malignant neoplasm of epidermal keratinocytes in which the component cells show variable squamous differentiation
Describe the histology of squamous cell carcinoma
- nests or islands of squamous cells arising from the epidermis and extending into the dermis or beyond
- variable keratinisation depending upon differentiation of the tumour (well differentiated = increased keratinisation)
What other differentials do you need to keep in mind when considering squamous cell carcinoma as a diagnosis?
- malignant (BCC, adnexal carcinoma)
- benign (seborrhoeic keratoses, viral warts)
- uncertain malignant potential (keratoacanthoma)
- premalignant/in-situ malignancy (actinic keratosis, Bowen’s disease)
What is included in the pathological report for cutaneous SCC?
- SCC subtype (most are of usual/no specific type)
- tumour grade
- level of invasion
- depth of invasion
- perineural infiltration
- lymphovascular invasion
- resection margins
- pT staging (UICC TNM8)
Describe the TNM8 clinical classification
- TX: primary tumour cannot be assessed
- T0: no evidence of primary tumour
- Tis: carcinoma in situ
- T1: tumour <20mm or less in maximum dimension
- T2: tumour >20mm to <40mm in maximum dimension
- T3: tumour >40mm in maximum dimension or minor erosion or perineural invasion or deep invasion (6+mm in depth or beyond subcutaneous fat)
- T4a: tumour with gross cortical/marrow invasion
- T4b: tumour with axial skeletom/skull base/foraminal invasion
What are the criteria for cutaneous SCC MDT referral?
1 factor required:
- clinical: site of ear, immunosuppression
- marcoscopic: tumour diameter >20mm
- pathological: poorly differentiated, >4mm thick, >subcutaenous fat, perineural invasion, desmoplastic subtype
What is needed in the pathology report for melanoma?
- tumour subtype
- breslow thickness
- presence of ulceration or not
- mitotic index
- lymphovascular invasion
- microsatellite or in-transit metastases
- perineural infiltration
- tumour infiltrating lymphocytes
- regression
- lymph node involvement
- distance to margins
What defines the Breslow thickness?
Measured from most superficial aspect of granular cell layer (or from base of ulcer) to deepest point of invasion
List the prognostic factors for melanoma
- tumour related (tumour thickness, mitotic rate, ulceration, extent of metastatic disease)
- LVI (lymphovascular invasion)
- PNI
- family history
- sun exposure, tanning beds
- molecular mutational gene expression, immunogenetics
Describe BRAF testing and targeted treatment
- for pT4b melanomas
- for metastatic melanomas including microsatellites
- qualitative detection of BRAF V600E mutation in DNA extracted from melanoma tissue
- selects patients for treatment with BRAF inhibitor (vemurafenib)
What characterises psoriasis?
- hyperkeratosis: thickened keratin layer
- parakeratosis: nuclei within keratin layer
- acanthosis: thickened epidermis
