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.

An introduction to dermatopathy is found in the dermatopathology article. Non-malignant disease is covered in the non-malignant skin disease article.

The Big Three malignant

Basal cell carcinoma

Squamous cell carcinoma of the skin

  • Abbreviated skin SCC, SCC of the skin, and SCC of skin.

General

Precursor:[1]

  • Actinic keratosis (solar keratosis).
    • Clinical: yellow-brown scaly, patches, sandpaper sensation.

Risk factors:[1]

  • Sun exposure.
  • Immune suppression (e.g. organ transplant recipients).

Notes:

  • Keratoacanthoma.
    • Some don't believe this entity exists.
      • These people sign this entity as low grade squamous cell carcinoma, keratoacanthoma type.[2]

Microscopic

High risk features - for SCC of the skin:[3]

  • Primary site is ear or lip.†
  • Clark level IV/V = reticular dermis or deeper.
  • >=2 mm thickness -- measured from granular layer (stratum granulosum) or ulcer base to deepest aspect.
  • Lymphovascular invasion.
  • Perineural invasion.
  • Poorly differentiated.

Note:

  • † The words used are "hair-bearing lip" - but there is considerable confusion about this as the AJCC manual contradicts itself.[4]

DDx:

Bowen disease

Bowen disease is squamous cell carcinoma in situ of the skin.

Histologic DDx of Bowen disease:

Images

IHC

Bowen's disease panel:

Sign-out

Invasive SCC

SKIN, SITE, BIOPSY: 
- MODERATELY-DIFFERENTIATED INVASIVE SQUAMOUS CELL CARCINOMA, SEE COMMENT. 
- NEGATIVE FOR LYMPHOVASCULAR INVASION.
- NEGATIVE FOR PERINEURAL INVASION.

COMMENT: 
The nearest margin (lateral margin) is 1 mm.  The tumour is 9 mm in maximal dimension.
SKIN LESION, SITE, EXCISION:
- INVASIVE SQUAMOUS CELL CARCINOMA, MODERATELY-DIFFERENTIATED.
-- TUMOUR GREATEST DIMENSION: ___ CM.
-- TUMOUR THICKNESS: ___ MM.
-- LATERAL MARGINS: POSITIVE FOR IN SITU CARCINOMA, < 0.1 MM FOR INVASIVE CARCINOMA.
-- DEEP MARGIN: POSITIVE FOR INVASIVE CARCINOMA.
-- NEGATIVE FOR LYMPHOVASCULAR INVASION.
-- NEGATIVE FOR PERINEURAL INVASION.
- EXTENSIVE SOLAR ELASTOSIS.
SKIN, SITE, BIOPSY: 
- INVASIVE SQUAMOUS CELL CARCINOMA, SEE TUMOUR SUMMARY.

TUMOUR SUMMARY:
Histologic type: squamous cell carcinoma, type not otherwise specified.
Histologic grade: moderately differentiated.
Greatest dimension: ___ cm.
Tumour thickness: ___ mm.
Peripheral margin: negative for invasive carcinoma and in situ carcinoma.
Deep margin (invasive component): negative for invasive carcinoma.
Closest margin: deep margin, ___ mm.
Lymphovascular invasion: not identified.
Perineural invasion: not identified.

Bowen's disease

SKIN LESION, RIGHT EAR, BIOPSY:
- SQUAMOUS CELL CARCINOMA IN SITU (BOWEN'S DISEASE), INCOMPLETELY EXCISED.

COMMENT:
Complete excision of the lesion is recommended.

Melanoma

General

  • Known as the great mimicker in pathology; it may look like many things.

Microscopic

Features:

  • Classic appearance of melanoma:
    • Loosely cohesive; mix of small nests of cells, single cells.
    • Usu. 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).
    • Often marked nuclear pleomorphism - variation in cell size, shape & staining (like in serous carcinoma of the ovary).
    • Nuclear pseudoinclusions (like in papillary thyroid carcinoma).

Less common malignant

Dermatofibrosarcoma protuberans

  • Abbreviated DFSP.

General

  • Dermal location.
  • Destroys adnexal structures.
  • Occasionally transforms to a (more aggressive) fibrosarcoma.[8]

Treatment:[9]

  • Wide excision.
  • May include imatinib (Gleevec).

Gross

Features:[10]

  • Firm plaque, often bosselated, usually on the trunk.
  • +/-Ulceration.

Images:

Microscopic

Features:[9]

  • Dermal spindle cell lesion with storiform pattern.
    • Spokes of the wheel-pattern.
  • Contains adipose tissue within the tumour -- key feature.
    • Described as "honeycomb pattern" and "Swiss cheese pattern".

Notes:

  • Adnexal structure within tumour are preserved -- this is unusual for a malignant tumour -- important.


DDx:

DDx of storiform pattern:

Images

www:

IHC

Panel:[12]

  • CD34 +ve.
    • Usually negative in dermatofibroma.[13][14]
  • Factor XIIIa -ve.
    • Usually positive in dermatofibroma.[13][14]
  • S100 -ve (screen for melanoma).
  • Caldesmin -ve (screen for muscle differentiation).
  • Beta-catenin. (???)
  • MIB1 (proliferation marker).
    • Should not be confused with MIB-1 a gene that regulates apoptosis.

Molecular

A characteristic translocation is seen:[15] t(17;22)(q22;q15) COLA1/PDGFB.

Cutaneous B-cell lymphoma

  • Abbreviated CBCL.

General

  • CBCL is less common than cutaneous T-cell lymphoma (CTCL).[16]

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).[17][18]

Stages - like Kaposi sarcoma:

  • Patch.
  • Plaque.
  • Nodular.

Microscopic

  • Atypical lymphocytes:
    • Have folded "cerebriform" nuclei; Sezary-Lutzner cells.[19]
  • Grouping:
    • Nests in the epidermis - known as "Pautrier microabscesses".
    • Single lymphocytes in epidermis - without accompanying edema.
    • Short linear arrays of lymphocytes along the basal layer of the epidermis; "epidermotropism".[19]

DDx:

Images

www:

IHC

Key stain:

Other stains:

  • CD3 +ve.
  • CD8 -ve.
  • CD20 -ve (to r/o significant B cell population).
  • CD30 -ve.
  • CD5 +ve.
  • CD7 -ve (often lost first in T cell lymphomas).
  • Ki-67 high.
  • CD56 -ve.

Merkel cell carcinoma

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).

Notes:

Kaposi sarcoma

See Kaposi sarcoma.

Sebaceous carcinoma

  • AKA sebaceous cell carcinoma.

General

Notes:

Gross

Features:[22]

  • Classically head and neck tumour.
  • Yellow or red (ulcerated) nodule.

Microscopic

Features:[23]

  • Sebaceous differentiation - may be a minor component - key feature.
    • Sebocytes = abundant pale fluffy cytoplasm with vacuolization.
  • Basaloid cells - often dominant.
    • May lead to confusion with basaloid tumours.
  • Nodular or diffuse growth pattern surrounded by a dense fibrous stroma.
  • Infiltrative border - important.
    • The key difference with sebaceous adenoma in cases where there isn't significant nuclear atypia.
  • +/-Nuclear atypia.
  • +/-Squamous differentiation.
  • +/-Foreign body-type giant cells.

DDx:

Images

www:

Grading

Three tier system:[23]

  • Well-differentiated - sebocytes predominant.
  • Moderately differentiated - sebocytes are easily recognized but a minor component.
  • Poorly differentiated - sebocytes are rare.

IHC

Features:[23]

Images:

Sign out

SKIN LESION, NOSE, BIOPSY:
- SEBACEOUS CARCINOMA, WELL-DIFFERENTIATED, COMPLETELY EXCISED IN THE PLANE OF SECTION.

COMMENT:
EMA staining marks the sebocytes.  The lesion is negative for Ber-EP4.

Sebaceous carcinoma may be seen in the context of Muir-Torre syndrome.

Micro

Well differentiated

The sections show well-circumscribed dermal nests of basaloid cells with peripheral palisading, surrounded by a dense fibrous stroma. The basaloid cells have distinct nucleoli. Focally, the basaloid nests contain small clusters of cells with abundant pale, vacuolated, fluffy-appearing cytoplasm (sebocytes). Mitotic activity is minimal.

There is no artefactual clefting between the stroma and basaloid cell nests. The epidermis matures to the surface and does not have basal atypia.

The lesion is completely excised in the plane of section.

Poor differentiated

The sections show well-circumscribed dermal nests of basaloid cells with peripheral palisading, surrounded by a dense fibrous stroma, that extend from the skin surface almost to the adipose tissue. The basaloid cells have moderate nuclear atypia with occasional monstrous cells. Mitotic activity is abundant and atypical mitoses are present. The nests contain rare cells with pale, fluffy-appearing cytoplasm, suggestive of sebocytes.

Microcystic adnexal carcinoma

  • AKA syringomatous carcinoma, AKA sclerosing sweat duct carcinoma.[26]

General

  • Low-grade tumour.
  • Adults.

Microscopic

Features:[27]

  • Small basaloid cells - often forming small cystic spaces - key feature.
    • Very bland cytology.
  • Fibrotic stroma.

DDx:

Image:

IHC

Features:[29]

Trichilemmal carcinoma

General

  • Super rare.
  • Not well-described.

Microscopic

Features:[30]

  • Clear (glycogen-rich) cytoplasm in center of lesion.
  • Peripheral palisading at edge of lesion - root sheath differentiation (hair follicle).
  • Contiguous with hair follicle or assoc. with trichilemmoma.

DDx:

Lymphomatoid papulosis

General

  • Rare.
  • Benign behaviour.

Microscopic

Features:

  • Dermal lymphocytosis.
    • No epidermal lymphocytes.
  • Focal nuclear atypia.

DDx:

IHC

Rare malignant

Basosquamous carcinoma

Should not be confused with basaloid squamous cell carcinoma (AKA squamous cell carcinoma, basaloid variant).

General

Microscopic

Features:

Note:

  • Busam notes that there is disagreement about what defines this tumour;[35] however, he goes on the describe it as a collision tumour.[34]

DDx:

Intermediate

Atypical fibroxanthoma

  • Abbreviated AFX.

General

Clinical:

  • Rapid growth.
  • Elderly.
  • Good prognosis.[40]

Microscopic

Features:[41]

  • Dermal lesion - key point.
  • Marked nuclear atypia.
  • Mitoses.
  • Mulitnucleated cells.
  • Foamy cytoplasm - key feature.

DDx:

Notes:

  • No Grenz zone. (???)

Image:

IHC

Features:[41]

  • S100 -ve (done to r/o melanoma).
  • 34betaE12 -ve.
  • p63 -ve (done to exclude SCC)
    • Scant staining not considered +ve.
  • Desmin -ve (done to r/o leiomyosarcoma).

Benign

Syringoma

General

  • Benign sweat duct tumour.
  • Eccrine differentiation.
  • Usually close to lower eyelid.[43]

Microscopic

Features:[44]

  • Proliferation of benign ducts with lined by a bilayer (as in normal sweat ducts) with abnormal architecture:
    • Tadpole like appearing ducts.

DDx:

Images:

Chondroid syringoma

  • Used to be called mixed tumour of skin.[47]

General

  • Mixed apocrine & eccrine tumour of skin, usually in the head & neck[47], especially nose and cheek.[48]
  • May be in major and minor salivary glands.[48]

Microscopic

Features:

  • Mix tumour with:[47]
    1. Epithelial component:
      • Nests of cells with:
        • Moderate dull eosinophilic cytoplasm.
        • Round/ovoid nuclei with nucleoli.
    2. Mesenchymal component - key feature:

Images:

Dermal cylindroma

General

May be familial:[50]

  • Familial cylindromatosis (autosomal dominant).
  • Brook–Spiegler syndrome.

Gross

  • Classically scalp - usually head and neck or face.

Microscopic

Features:[50]

  • Nests of cells that fit together like a jigsaw puzzle - the borders of the nests are opposed and undulate.
    1. Basaloid cells with scant cytoplasm and dark nuclei palisade around the edge of the nests.
    2. Larger cells with moderate eosinophilic cytoplasm and lighter staining nuclei are at the centre of the nests.
  • Cells nests surrounded by a band of hyaline (i.e. glassy, eosinophilic, acellular) material ~ 2X thickness of a basilar cell - key feature.
    • This is basement membrane.

DDx:

Images

www:

Stains

  • PAS +ve (basement membrane).[50]

Keratoacanthoma

Sebaceous adenoma

General

Notes:

Microscopic

Features:

  • Abnormal sebaceous glands (pale fluffy cytoplasm):
    • Increased basal epithelium.
    • Multiple dilated glands - opening to the surface.

Images

www:

Trichilemmoma

  • May be spelled tricholemmoma.

General

  • Benign neoplasm with features of the pilosebaceous follicular epithelium.[53]
  • Associated with nevus sebaceous.[54]
  • Muliple trichilemmomas associated with Cowden syndrome.[55]

Microscopic

Features:[55]

  • Superficial dermal lesion contiguous with the epidermis:
    • Core of lesion:
      • Cuboidal cells with round nuclei, eosinophilic-clear cytoplasm.
    • Periphery of lesion:
      • Surrounded by hyaline band.
      • Peripheral palisading.

DDx:

Images:

Eccrine poroma

General

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

Microscopic

Features:[58]

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

Notes:

  • Area above gland appears crusted.

DDx:

Images:

Nodular hidradenoma

General

  • Benign adnexal tumour.[60]

Typical locations:[59]

  • Scalp.
  • Face.
  • Trunk, anterior.

Microscopic

Features:[60]

  • Well-circumscribed dermal lesions with:
    • Back-to-back nests with a whorled appearance.
    • Spaces between cells.
    • Nuclei ovoid and centrally placed in the cell.
      • No nucleolus.
    • Cystic spaces with degenerated cells.

DDx:

Images

IHC

Features:[60]

  • CAM5.2 +ve.
  • AE1/AE3 +ve.
  • EMA +ve.
  • S100 -ve.
  • Desmin -ve.

Trichoblastoma

  • AKA trichoepithelioma.
    • Trichoepithelioma is considered a superficial version of trichoblastoma; WHO lumps the two entities together.[61]

General

  • Benign.
  • May be familial:
    • Multiple familial trichoepithelioma.[62]
    • Brooke-Spiegler syndrome.

Microscopic

Features:[63]

  • Well-circumscribed cell nest in the superficial dermis.
  • Surrounding by a fibrous stroma.
  • Basaloid cells with peripheral palisading.
  • +/-Surround keratin-filled cysts.
  • Fibroblasts-like cell aggregate, similar to a follicular papillae (papillary-mesenchymal body).

Notes:

Variants:

  • Desmoplastic trichoblastoma.

DDx:

Images

www:

Sign out

SKIN LESION, NOSE, BIOPSY:
- TRICHOBLASTOMA, COMPLETELY EXCISED.

Micro

The sections show well-circumscribed dermal nests of basaloid cells with peripheral palisading surrounded by a dense fibrous stroma. There is no artefactual clefting between the stroma and basaloid cell nests. Mitotic activity is minimal. Smaller hyperchromatic spindled-to-epithelioid cells in clusters (papillary-mesenchymal bodies) are found within the basaloid cells nests.

The epidermis show maturation to the surface and does not have basal atypia.

The lesion is completely excised in the plane of section.

Trichofolliculoma

General

  • Benign.

Microscopic

Features:[66]

  • Irregular hair follicle (basilar nest of cells with an acellular hair shaft) with:
    • Smaller satellites (follicles) consisting of well-circumscribed basilar cells.

Note:

  • Lack artificial clefting between the (basilar) nests and stroma (seen in BCC).
  • Surrounding stroma does not have a basophilic tingle (seen in BCC).

DDx:

Images

www:

Apocrine carcinoma of the skin

General

  • Rare.[67]
  • Usually very good prognosis.[67]

Microscopic

Features:[67]

  • Nests.
  • Apocrine snouts - "decapitation secretion"

DDx:

Images

Stains

Features:[67]

  • PAS +ve.
  • PASD +ve.

IHC

  • GCDFP-15 (gross cystic disease fluid protein-15) +ve.[67]

Dermatomyofibroma

Should not be confused with dermatofibroma.
  • Abbreviated DMF.

General

  • Uncommon.

Microscopic

Features:[11]

  • Poorly formed fasicles parallel to the skin surface, usu. restricted to the superficial dermis.
  • Moderate cellular density - less cellular than DFSP.
  • Eosinophilic cytoplasm.

DDx:

Images:

IHC

Features:[11]

  • CD10 +ve.
  • Vimentin +ve.

Others:[11]

  • CD34 -ve.
  • Factor XIIIa -ve.
  • S-100 -ve.

Papillary eccrine adenoma

  • Abbreviated PEA.

General

  • Uncommon.
  • Benign.[68]

Treatment:

Gross

  • Central location.

Note:

  • The digital papillary adenoma is considered malignant; the AFIP says these are best classified as adenocarcinomas, i.e. digital papillary adenocarcinoma.[70]

Microscopic

Features:[71][72]

  • Well-circumscribed lesions consisting of multiple cystic spaces lined by a bilayered epithelium with:
    • Papillary projections into the lumen.
    • Amorphous eosinophilic material in the cystic spaces.
    • Surrounded by a fibrous stroma.[73]

Note:

  • May appear to have more than two cell layers.

DDx:

Image:

IHC

Outer layer of epithelium:[73]

  • SMA-alpha +ve.
  • Keratin 14 +ve.

Inner layer of epithelium:[73]

  • Keratin 8 +ve.

Other stains:[72]

  • Vimentin +ve.
  • CEA +ve.
  • EMA +ve.
  • S-100 +ve.

Sign out

SKIN LESION, LEFT PARIETAL SCALP, BIOPSY:
- PAPILLARY ECCRINE ADENOMA.

Micro

The sections show a well-circumscribed multi-locular superficial dermal lesion with a bilayered epithelium and intracystic papillary projections. The cystic spaces contain amorphous eosinophilic material. The cystic component is surrounded by a dense fibrous stroma with a mixed inflammatory infiltrate, consisting primary of plasma cells and lymphocytes.

There is no significant nuclear atypia and no mitotic activity is appreciated. The overlying epidermis matures appropriately. A granular layer is present.

See also

References

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