Difference between revisions of "Malignant melanoma"

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===Breslow thickness===
===Breslow thickness===
*Depth measured from stratum granulosum to deepest intradermal tumour cell - predictive of survival.<ref>{{Ref PCPBoD8|595}}</ref>
*Depth measured from stratum granulosum to deepest intradermal tumour cell - predictive of survival.<ref>{{Ref PCPBoD8|595}}</ref>
===Subtypes===
===Benign lesions===
{| class="wikitable sortable" style="margin-left:auto;margin-right:auto"
| '''Subtype name'''
| '''Key feature'''
| '''Microscopic additional'''
| '''DDx'''
| '''Image'''
| '''Notes/other'''
|-
| Melanoma in situ
| confined to epidermis, nuclear atypia
| melanocyte enlargement, nuclear hyperchromasia, +/- melanocytes above suprapapillary plate (above basal layer) = "Pagetoid spread"
| melanocytic hyperplasia, pagetoid Spitz nevus
| Image?
| Notes/other?
|-
| Malignant melanoma - superficial spreading type
| atypical melanocytes at all levels of epidermis + dermis
| atypical dermal melanocytes single, in cluster or sheets
| compound melanocytic nevus
| Image?
| Notes/other?
|-
| Malignant melanoma - lentiginous type
| atypical melanocytes prominent along basal keratinocytes + in dermis
| nuclear atypia
| DDx?
| Image?
| Notes/other?
|-
| Malignant melanoma - nodular type
| dermal large nodule/sheet
| nuclear atypia; may not be prominent in epidermis
| metastatic melanoma
| Image?
| Notes/other?
|-
| Malignant melanoma - desmoplastic-neurotropic type
| large atypical spindle cells, btw collagen
| predominantly dermal
| [[pleomorphic undifferentiated sarcoma]] (MFH), [[scar]], [[dermatofibroma]], [[DFSP]], [[leiomyosarcoma]]
| Image?
| Notes/other?
|-
| Malignant melanoma - nevoid type
| prominent nucleoli, deep mitoses - high power diagnosis
| mimics nevus at low power
| (benign) nevus
| Image?
| Notes/other?
|-
| Malignant melanoma - spitzoid type
| nested pattern, nuclear atypia, no maturation (large deep cells)
| NC ratio increased (vs. Spitz)
| [[Spitz nevus]]
| Image?
| Notes/other?
|}


==[[Electron microscopy]]==
==[[Electron microscopy]]==

Revision as of 13:10, 9 September 2011

Malignant melanoma, also melanoma, is an aggressive type of skin cancer that can be diagnostically challenging for pathologists.

It fits into the larger category of melanocytic lesions which includes many benign entities, a number of which can be difficult to distinguish from melanoma.

General

  • AKA Malignant melanoma.
  • Main DDx: melanocytic lesions - especially if pigmented.
  • Known as the great mimicker in pathology; it may look like many things.

Clinical

  • ABCD = asymmetric, borders (irregular), colour (black), diameter (large).

Microscopic

Features:

  • Classic appearance of melanoma:
    • Loosely cohesive; mix of small nests of cells, single cells.
    • Mixed of spindle and ovoid cell morphology.
    • +/-Occasional large binucleated cells.
    • Cytoplasm: brown pigment (melanin).
    • Prominent (large) red nucleoli (like in serous carcinoma of the ovary).
    • Marked nuclear pleomorphism - variation in cell size, shape & staining (like in serous carcinoma of the ovary).
    • Nuclear pseudoinclusions (like in papillary thyroid carcinoma).

Notes:

  • Can look almost like anything.
    • Like it is said that sarcoidosis is in every internal medicine DDx... melanoma is every pathologic DDx.

DDx

  • Carcinoma.
    • Serous carcinoma - both serous carcinoma and melanoma have a large nucleolus.
  • Sarcoma - as may have spindle cells.
  • Lymphoma.
  • Other melanocytic lesions.

Breslow thickness

  • Depth measured from stratum granulosum to deepest intradermal tumour cell - predictive of survival.[1]

Subtypes

Benign lesions

Subtype name Key feature Microscopic additional DDx Image Notes/other
Melanoma in situ confined to epidermis, nuclear atypia melanocyte enlargement, nuclear hyperchromasia, +/- melanocytes above suprapapillary plate (above basal layer) = "Pagetoid spread" melanocytic hyperplasia, pagetoid Spitz nevus Image? Notes/other?
Malignant melanoma - superficial spreading type atypical melanocytes at all levels of epidermis + dermis atypical dermal melanocytes single, in cluster or sheets compound melanocytic nevus Image? Notes/other?
Malignant melanoma - lentiginous type atypical melanocytes prominent along basal keratinocytes + in dermis nuclear atypia DDx? Image? Notes/other?
Malignant melanoma - nodular type dermal large nodule/sheet nuclear atypia; may not be prominent in epidermis metastatic melanoma Image? Notes/other?
Malignant melanoma - desmoplastic-neurotropic type large atypical spindle cells, btw collagen predominantly dermal pleomorphic undifferentiated sarcoma (MFH), scar, dermatofibroma, DFSP, leiomyosarcoma Image? Notes/other?
Malignant melanoma - nevoid type prominent nucleoli, deep mitoses - high power diagnosis mimics nevus at low power (benign) nevus Image? Notes/other?
Malignant melanoma - spitzoid type nested pattern, nuclear atypia, no maturation (large deep cells) NC ratio increased (vs. Spitz) Spitz nevus Image? Notes/other?

Electron microscopy

  • Melanosomes.

Image(s):

Stains

  • Fontana-Masson stain, stains melanin.[2]
    • May be useful to differentiate melanin from other brown stuff (e.g. lipofuscin, hemosiderin).

IHC

Standard panel:

  • S-100 +ve.
  • HMB-45 +ve.
  • Melan A (MART-1) +ve.

Others:

  • SOX10 +ve -- useful for diff. from excision scar.[3]
    • SOX-10 = pan-schwannian and melanocytic marker.

Notes:

  • The standard panel above (S-100, HMB-45, MART-1) is also positive in other lesions, e.g. cellular blue nevus.

See also

References

  1. ↑ Mitchell, Richard; Kumar, Vinay; Fausto, Nelson; Abbas, Abul K.; Aster, Jon (2011). Pocket Companion to Robbins & Cotran Pathologic Basis of Disease (8th ed.). Elsevier Saunders. pp. 595. ISBN 978-1416054542.
  2. ↑ URL: http://education.vetmed.vt.edu/curriculum/VM8054/labs/Lab2/Examples/exfontana.htm. Accessed on: 5 May 2010.
  3. ↑ Ramos-Herberth FI, Karamchandani J, Kim J, Dadras SS (September 2010). "SOX10 immunostaining distinguishes desmoplastic melanoma from excision scar". J. Cutan. Pathol. 37 (9): 944–52. doi:10.1111/j.1600-0560.2010.01568.x. PMID 20653825.
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