Difference between revisions of "Malignant melanoma"
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DDx: | DDx: | ||
*Carcinoma | *Carcinoma. | ||
**Esp. serous carcinoma - both serous carcinoma and melanoma have a large [[nucleolus]]. | |||
*Sarcoma - as may have spindle cells. | *Sarcoma - as may have spindle cells. | ||
**Esp. [[clear cell sarcoma]]. | |||
*Lymphoma. | *Lymphoma. | ||
Revision as of 20:45, 3 May 2011
Malignant melanoma, also melanoma, is an aggressive type of skin cancer that can be diagnostically challenging for pathologists.
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).
DDx:
- Carcinoma.
- Esp. serous carcinoma - both serous carcinoma and melanoma have a large nucleolus.
- Sarcoma - as may have spindle cells.
- Esp. clear cell sarcoma.
- Lymphoma.
Notes:
- Can look almost like anything.
- Like it is said that sarcoidosis is in every internal medicine DDx... melanoma is every pathologic DDx.
- Melanomas with:
- An epitheloid cell morphology may mimic adenocarcinoma.
- A spindle cell morphology may mimic spindle cell carcinoma (squamous cell carcinoma) or a sarcoma.
Electron microscopy
- Melanosomes.
Image(s):
Stains
- Fontana-Masson stain, stains melanin.[1]
- 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.[2]
- 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
- ↑ URL: http://education.vetmed.vt.edu/curriculum/VM8054/labs/Lab2/Examples/exfontana.htm. Accessed on: 5 May 2010.
- ↑ 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.