Pathology Flashcards
What is a melanoma and why is it different from a SCC?
It is a malignant neoplasm of melanocytes that produce melanin in the deeper epidermis that is caused by intermittent sun exposure whereas SCC is malignant neoplasm of squamous cells of superficial epidermis requiring continuous sun exposure
Other differences:
- Melanoma affects younger people
- SCC develops anywhere whereas melanoma develops in particularly sun exposed areas
- SCC is red scaly patch/non-healing sore whereas melanoma is multi-coloured asymmetrical mole with uneven borders
- SCC more common overall
- SCC rarely metastasizes
- Melanoma has poorer prognosis
What is important to know in biopsy report of skin cancer?
Breslows thickness: tumour depth from stratum granulosum (mm) - in situ (95-100% survival), <1mm (95-100%), 1-2mm (80-95%), 2-4mm (60-75%) & >4mm (50%)
Clarks level: anatomical level of invasion (level I-V depending on layer it has penetrated)
Ulceration
Presence of mitoses
Lymphovascular invasion
IHC for proliferation markers e.g. Ki-67
What excision margins should you aim for in melanoma? How might you determine margins intra-operatively?
If in situ <0.5mm = 0.5cm
If <2mm = 1cm margin
If >2mm = 2cm margin
If >4mm = 3cm margin
Frozen section: pathological laboratory procedure used to perform rapid microscopic analysis of a specimen = cryosection where cryotome device cold cuts thin blocks of frozen tissue
Mohs micrographic surgery: thin layers removed one a time and examined under the microscope to determine if cancer remains
What genes are responsible for familial melanoma? Name 2 conditions associated with it.
CDKN2A
CDK4
RB1 (retinoblastoma
BRCA2
- Xeroderma pigmentosum: autosomal recessive genetic disorder of DNA repair so damage from UV light cannot be corrected
- Albinism: congenital disorder characterised by complete/partial absence of skin, hair & eye pigmentation due to absent/deficiency tyrosinase
What are poor prognostic factors in melanoma?
Male
Older age
Ulceration
Site: LL, UL, trunk & head/neck
Patient complains of arm pain and swelling after axillary clearance. What is the diagnosis? If there was a mass instead in axilla what would you do?
Axillary vein thrombosis as malignancy causes prothrombotic state (Virchows triad = endothelial injury, hypercoagulability & stasis of blood)
If there was mass FNAC
How do you treat DVT?
Parenteral anticoagulation: LMWH, Fondaparinoux or Warfarin 1-10mg/day for 6 months to keep INR 2-3
Maintain them on treatment for at least 6 months
Catheter directed thrombolysis if <14days old or acute phlegmasia cerulea dolens present (if >14 days thrombus organisation prevents it working)
TPA (0.5-1mg/hour for 8 hours with labs 8 hourly to monitor fibrinogen - needs to be >100mg/dl otherwise major haemorrhage) then systemic anticoagulation with warfarin for 6 months
SVC filter if failure/contraindication to anticoagulation or for surgical prophylaxis if severe risk factors
What are the macroscopic vs microscopic features of malignant lesion?
Macroscopic:
- Not well circumscribed
- Invading BM & surrounding tissues
- Haemorrhage
- Necrosis
Microscopic:
- Anaplasia
- Large & irregular nucleoli
- High nuclear to cytoplasmic ratio
- Hyperchromatism
- Increased mitoses
What is histology vs cytology?
Histology: study of tissue architecture so will inform of invasion of surrounding stuctures
Cytology: studies of individual cells so can’t tell you about malignancy
What is BCC? What is its natural progression?
Cancer of basal cells in skin in deepest epidermal layer - usually indolent with slow progression, locally destructive but limited potential to metastasize
What are the treatment options for BCC?
- Curettage/cautery: scraping it away and preventing bleeding with cautery
- Cryotherapy with liquid nitrogen: cant obtain biopsy this way
- Excision with primary closure, flaps or secondary intention healing with margins of 4mm
- Mohs micrographic surgery (especially if recurrent or margins not clear)
- Radiotherapy
- Topical photodynamic therapy: δ-Aminolevulinic acid so tumour absorbs porphyrin metabolite converting it to protoporphyrin IX as its become photosensitive & subject to photodestruction when exposed to light
- Topical fluorouracil 5% or imiquimod 5%
What is the commonest cause of graft failure?
Wound infection by S. Aureus
How do you manage active Methicillin-Resistant S. Aureus (MRSA) infection?
If inpatient: infected tissue to be debrided & cultured + broad spectrum IV Abx pending culture results e.g. Vancomycin
If outpatient: PO Clindamycin, Linezolid or Amoxicillin (+ tetracycline)
What do reed-sternberg cells in a FNAC indicate?
Hodgkins lymphoma
