Melanoma in situ specimen

Question 1

Describe the case for this specimen?

Answer 1

Case: 60yo male, mid-upper back shave excision biopsy. PMHx prev melanoma in situ shave excision biopsy at same site.

Relevant negatives:
o No FMHx
o Lesion not fluctuant, not trans-illuminated, no signs of inflammation
o No pain, erythema, fever, tenderness, swelling or loss of function
o No other similar lesion: but few other moles present on face, arms and legs
o No palpable LNs

Question 2

What are some red flags for melanoma when examining a skin lesion?

Answer 2

Warning signs for melanoma (ABCDEs mnemonic): 
A- Asymmetry
B- Border irregular
C- Colour irregular
D- Diameter (>6mm)
E- Evolving
Also bleeding and ulceration.

Question 3

Describe the macroscopic appearance of the lesion?

Answer 3

Macroscopic appearance:
• Pigmented tan brown lesion with pale-white patches
• Measuring 33mm x 20mm x 18mm
• Irregular margins and irregular pigmentation
• Radial (horizontal) growth within epidermis, nil angiogenesis
• Nil bleeding or ulceration

Specimen orientation: the short suture (superior, inked blue) is designated as 12 o’clock and long suture (lateral, inked black) is designated as 9 o’clock -> allows for fine sectioning of specimen with orientation maintained and path exam

Question 4

Describe the microscopic appearance of the specimen?

Answer 4

Microscopic appearance:
• In situ: atypical melanocytes in epidermis w NO dermal invasion
• Epidermal effacement
• Confluence growth of melanocytes along dermoepidermal junction
• Pagetoid spread (“upward spreading” of abnormal cells in the epidermis, i.e. from bottom to top)

Question 5

Describe the process of melanoma pathogenesis?

Answer 5

Uncontrolled growth of melanocytes (pigment cells)
Location: skin (most), oral and anogenital mucosa, oesophagus, meninges, eye
Pigmentation: black, brown, red, dark blue, grey

1) DNA damage:
- > thymine-thymine dimers and ROS
- > single strand breaks and pyrimidine/purine oxidation -> unrepaired
- > mutations during DNA replication (e.g. cytosine to thymine UV mutation)
2) mutations in proto-oncogenes or tumour suppressor genes
3) uncontrolled melanocyte growth
- > radial
- > vertical
- > regression/metastases

Question 6

What are the stages and associated prognoses?

Answer 6

Stages and prognosis:
• Stage 0: melanoma in situ -> 99.9% survival in 5yrs
• Stage 1/2: invasive melanoma -> 89-95% survival in 5yrs
• Stage 2: high risk melanoma -> 45-79% survival in 5 yrs
• Stage 3: regional metastasis -> 24-70% survival in 5yrs
• Stage 4: distant metastasis -> 7-19% survival in 5 yrs