Dermatologic neoplasms

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This article deals with dermatologic neoplasms. It includes dermatologic cancer, which can be deadly. Collectively, dermatologic cancers are the most common form 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.
      • These people sign this entity as low grade squamous cell carcinoma, keratoacanthoma type.[2]

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

Microscopic

Features:[4]

  • Artefactual separation of basal cell layer from underlying stroma.
  • Palisading hyperchromatic cells.

Notes:

DDx:

  • Trichoepithelioma.

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.
  • 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.[5]
    • 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.[6]

Notes:

  • The standard panel above (S-100, HMB-45, MART-1) is also positive in other lesions, 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:[7]

  • CD34 +ve.
    • Usually negative in dermatofibroma.[8][9]
  • Factor XIIIa -ve.
    • Usually positive in dermatofibroma.[8][9]
  • 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 B-cell lymphoma

  • Abbreviated CBCL.

General

  • CBCL is less common than cutaneous T-cell lymphoma (CTCL).[10]

Microscopic

Features:

  • Dermal lymphoid infiltrate.
  • "Grenz zone" - space between the epidermis and the dermal infiltrate - key feature.

IHC

  • B cell and T cell markers.

Cutaneous T-cell lymphoma

  • Abbreviated CTCL.

General

  • Mycosis fungoides - is a subtype (???).
  • CTCL is more common than cutaneous B-cell lymphoma (CBCL).[11][12]

Microscopic

  • Atypical lymphocytes:
    • Have folded "cerebriform" nuclei; Sezary-Lutzner cells.[13]
  • Grouping:
    • Nests in the epidermis - known as "Pautrier microabscesses".
    • Single lymphocytes in epidermis; "lymphocyte exocytosis".[14]
    • Short linear arrays of lymphocytes along the basal layer of the epidermis; "epidermotropism".[13]

Images:

Merkel cell carcinoma

General

Features:[15]

  • Rare.
  • Aggressive course/poor prognosis.
  • Neuroendocrine-like.[16]

Etiology:

  • Polyomavirus (?).[15]
  • Immunocompromised/immunosuppressed (e.g. organ transplant recipients).

Microscopic

Features:[17]

  • Nests or sheets or trabeculae.
  • Scant cytoplasm.
  • Nuclear moulding.
  • Multiple small nucleoli.
  • Usually mitotically active.

Image:

IHC

  • CK7 -ve, CK20 +ve

Eccrine carcinoma

General

  • Arises from the proximal sweat duct.

Microscopic

Features:

  • Pleomorphic nuclei with nucleoli.
  • Duct-like structures - key feature.
  • Extends from dermis into epidermis (follows path of a benign sweat duct).

Image: Eccrine carcinoma - intermed. mag. (WC).

Eccrine poroma

General

  • Benign tumour arising from the distal sweat duct.
  • Erythematous - gross.

Microscopic

Features:[18]

  • Broad sheets of basaloid cells containing ductal structures - key feature.
  • Biphasic stroma:
    1. Edematous stroma.
    2. Sclerotic stroma.
  • Moderate nuclear pleomorphism.
  • +/-Occasional mitoses.

Notes:

  • Area above gland appears crusted.

Kaposi sarcoma

See Kaposi sarcoma.

See also

References

  1. ↑ TN07 D6.
  2. ↑ RS. 17 May 2010.
  3. ↑ URL: http://emedicine.medscape.com/article/1101146-diagnosis. Accessed on: 6 May 2010.
  4. ↑ NEED REF.
  5. ↑ URL: http://education.vetmed.vt.edu/curriculum/VM8054/labs/Lab2/Examples/exfontana.htm. Accessed on: 5 May 2010.
  6. ↑ 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.
  7. ↑ AP. May 2009.
  8. ↑ 8.0 8.1 PMID 7694515.
  9. ↑ 9.0 9.1 PMID 9129699.
  10. ↑ URL: http://emedicine.medscape.com/article/1099540-overview. Accessed on: 24 August 2010.
  11. ↑ URL: http://emedicine.medscape.com/article/1099540-overview. Accessed on: 24 August 2010.
  12. ↑ URL: http://emedicine.medscape.com/article/1098342-overview. Accessed on: 24 August 2010.
  13. ↑ 13.0 13.1 Klatt, Edward C. (2006). Robbins and Cotran Atlas of Pathology (1st ed.). Saunders. pp. 385. ISBN 978-1416002741.
  14. ↑ 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.
  15. ↑ 15.0 15.1 Calder, KB.; Smoller, BR. (May 2010). "New insights into merkel cell carcinoma.". Adv Anat Pathol 17 (3): 155-61. doi:10.1097/PAP.0b013e3181d97836. PMID 20418670.
  16. ↑ Pulitzer, MP.; Amin, BD.; Busam, KJ. (May 2009). "Merkel cell carcinoma: review.". Adv Anat Pathol 16 (3): 135-44. doi:10.1097/PAP.0b013e3181a12f5a. PMID 19395876.
  17. ↑ Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 491. ISBN 978-0781765275.
  18. ↑ URL: http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675(06)70190-5. Accessed on: 2 July 2010.
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