Difference between revisions of "Dermatologic neoplasms"
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==Melanoma== | ==Melanoma== | ||
*AKA ''Malignant melanoma''. | *[[AKA]] ''Malignant melanoma''. | ||
*Main DDx: [[melanocytic lesions]] - especially if pigmented. | |||
*Known as the great mimicker in pathology; it may look like many things. | |||
===Clinical=== | ===Clinical=== | ||
Revision as of 14:47, 13 May 2010
Dermatologic cancer can be deadly. Collectively, they are the most common forms of cancer.
Squamous cell carcinoma
Precursor:[1]
- Actinic keratosis (solar keratosis).
- Clinical: yellow-brown scaly, patches, sandpaper sensation.
- Keratocathoma - see non-malignant skin disease.
- Some don't believe this entity exists - that it's a low grade SCC.
Basal cell carcinoma
General
- Very common.
- Sun exposed skin.
- Very rarely metastasizes - so rare... some don't think this is really a malignancy.
Clinical
- Telangiectasias.
- Raised pearly nodule.
As part of a syndrome
- Nevoid basal cell carcinoma syndrome (NBCCS), AKA Gorlin syndrome.
- Bazex syndrome (X-linked).[2]
Microscopic
Features:[3]
- Artefactual separation of basal cell layer from underlying stroma.
- Palisading hyperchromatic cells.
Notes:
- There are various subtypes: http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675%2806%2970110-3.
DDx:
- Trichoepithelioma.
Melanoma
- 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).
Histology
- 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.
- Melanomas with:
- An epitheloid cell morphology may mimic adenocarcinoma.
- A spindle cell morphology may mimic spindle cell carcinoma (squamous cell carcinoma) or a sarcoma.
Stains
- Fontana-Masson stain, stains melanin.[4]
- May be useful to differentiate melanin from other brown stuff (e.g. lipofuscin, hemosiderin).
Electron microscopy
- Melanosomes.
Image(s):
IHC
Standard panel:
- S-100 +ve.
- HMB-45 +ve.
- Melan A (MART-1) +ve.
Notes:
- The standard panel above is positive in other lesions also, e.g. cellular blue nevus.
Dermatofibrosarcoma protuberans
General
- Abbreviated DFSP.
- Dermal location.
- Destroys adnexal structures.
Treatment
- Wide excision.
Histology
- Spindle cell morphology.
- Contains adipose tissue within the tumour -- key feature.
IHC
Panel:[5]
- CD34 +ve.
- S100 -ve (screen for melanoma).
- caldesmin -ve (screen for muscle differentiation).
- beta-catenin ???.
- MIB-1 (proliferation marker) -- should not be confused with MIB1 a gene that regulates apoptosis.
DDx - histologic
- Dermatofibroma - has entrapment of collagen bundles at the edge of the lesion.
Cutaneous T cell lymphoma
- Abbreviated CTCL.
- Mycosis fungoides - is a subtype (???).
Microscopic
- Atypical lymphocytes:
- Have folded "cerebriform" nuclei; Sezary-Lutzner cells.[6]
- Grouping:
Images:
Merkel cell carcinoma
General
Features:[9]
- Rare.
- Aggressive course/poor prognosis.
- Neuroendocrine-like.[10]
Etiology:
- Polyomavirus (?).[9]
- Immunocompromised/immunosuppressed (e.g. organ transplant recipients).
Microscopic
Features:[11]
- Nests or sheets or trabeculae.
- Scant cytoplasm.
- Nuclear moulding.
- Multiple small nucleoli.
- Usually mitotically active.
Image:
IHC
- CK7 -ve, CK20 +ve
See also
References
- ↑ TN07 D6.
- ↑ URL: http://emedicine.medscape.com/article/1101146-diagnosis. Accessed on: 6 May 2010.
- ↑ NEED REF.
- ↑ URL: http://education.vetmed.vt.edu/curriculum/VM8054/labs/Lab2/Examples/exfontana.htm. Accessed on: 5 May 2010.
- ↑ AP May 2009.
- ↑ Klatt. AOP. P.385.
- ↑ URL: http://www.mdconsult.com/das/book/body/199872830-2/0/1709/I4-u1.0-B978-0-443-06694-8..50117-2--f2.fig. Accessed on: 6 May 2010.
- ↑ Klatt. AOP. P.385.
- ↑ 9.0 9.1 PMID 20418670.
- ↑ PMID 19395876.
- ↑ WMSP P.491.