Squamous cell carcinoma of the skin

Squamous cell carcinoma of the skin
Diagnosis in short
Squamous cell carcinoma. H&E stain.
Subtypes	many see squamous cell carcinoma
LM DDx	inverted follicular keratosis, Paget disease of the breast, eccrine carcinoma, atypical fibroxanthoma, malignant melanoma, leiomyosarcoma, basal cell carcinoma (for basaloid squamous cell carcinoma), porocarcinoma, pseudoepitheliomatous hyperplasia
IHC	CK5/6 +ve, p63 +ve, K903 +ve, Ber-EP4 -ve, S-100 -ve
Gross	scaly patch or nodule, +/-ulceration
Staging	squamous cell carcinoma of the skin staging
Site	skin - usu. sun exposed areas
Associated Dx	actinic keratosis, solar elastosis
Clinical history	old age, +/-immunosuppression, +/-immunodeficiency
Prevalence	common
Prognosis	fairly good, may metastasize
Clin. DDx	other skin tumours

Squamous cell carcinoma of the skin is a common malignant neoplasm of the skin.

It is abbreviated skin SCC, SCC of the skin, and SCC of skin.

The general topic of squamous cell carcinoma, also squamous carcinoma, is dealt with in the squamous cell carcinoma article.

General

Precursor:

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

Risk factors:

• 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.

Gross

Features:

• Scaly patches/nodules.
• Usu. erythematous.
• +/-Ulceration.
• "Keratin" plugs appearance.

Notes:

• Typically sun exposed areas.

Microscopic

• See squamous cell carcinoma.

High risk features - for SCC of the skin:

• 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.

DDx:

• Inverted follicular keratosis.
• Bowen disease.
• Malignant melanoma.
• Paget disease of the breast.
• Eccrine carcinoma.
• Basal cell carcinoma for basaloid squamous cell carcinoma.
• Porocarcinoma.
• Pseudoepitheliomatous hyperplasia.

Grading

• G1 - well differentiated - easily recognizable as squamous, abundant keratinization.
• G2 - moderately differentiated - keratinization focal (typically limited to keratin pearls, individual cells or horn cysts).
• G3 - poorly differentiated - difficult to establish as squamous.
• G4 - undifferentiated or anaplastic.

Images

• 

  SCC - anaplastic. (WC)

Bowen disease

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

• Its histomorphologic appearance may be similar to Paget disease of the breast/Extramammary Paget disease, Toker cell hyperplasia and melanoma.
  • IHC is used to separate the entities definitively.

Histologic DDx of Bowen disease:

• Benign Toker cell hyperplasia.
• Malignant melanoma.
• Paget disease of the breast.
• Eccrine carcinoma.

Images

• 

  Bowen disease - 1. (WC)

• 

  Bowen disease - 2. (WC)

• 

  Bowen disease - 3. (WC)

IHC

Bowen's disease panel:

• CK5/6 +ve.
  • Usu. -ve in Paget disease of the breast/Extramammary Paget disease.
• S100 -ve, HMB-45 -ve.
  • Both typically +ve in melanoma.
• CEA -ve (+ve in Paget disease of the breast/Extramammary Paget disease, -ve in Toker cells).
• CK7 -ve.
  • Toker cells CK7 +ve.

Others:

• Ber-EP4 usually -ve.
  • Usually +ve in BCC.
• EMA +ve (~83% +ve).
  • Usually -ve in BCC.

Staging

Tumour stage

T stage	Criteria	Comment
T1	<=2 cm and less than two high-risk factors	see microscopic for list of high-risk factors
T2	>2 cm and less than two high-risk factors or two or more high-risk factors	see microscopic for list of high-risk factors
T3	tumour into nearby bone - maxilla, mandible, orbit, temporal bone	uncommonly seen by pathology
T4	tumour into axial skeleton or appendicular skeleton or perineural invasion of skull base	basically never seen by pathology

Sign-out

Invasive SCC - small

Scalp Lesion, Excision:
- INVASIVE SQUAMOUS CELL CARCINOMA, well-differentiated.
-- Margins NEGATIVE for carcinoma in situ and NEGATIVE for malignancy.
--- Closest margin (deep margin): 4 mm.
-- Maximal tumour dimension: 1.2 cm.
-- NEGATIVE for lymphovascular invasion.
-- NEGATIVE for perineural invasion.
- Extensive solar elastosis.

Invasive SCC - large

Skin Lesion, Mid-Back, Excision:
- Invasive SQUAMOUS CELL CARCINOMA, moderately differentiated.
- Margins NEGATIVE for carcinoma in situ and NEGATIVE for malignancy.
-- Closest margin: > 10 mm.
-- TNM stage: pT2 pN0.
- Extensive solar elastosis.
- Two benign lymph nodes (0/2).
- Please see synoptic report.

Block letters

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: NEGATIVE FOR IN SITU CARCINOMA AND INVASIVE CARCINOMA.
-- DEEP MARGIN: NEGATIVE FOR INVASIVE CARCINOMA.
-- NEAREST MARGIN: 1 MM, LATERAL MARGIN.
-- 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.

SKIN LESION, CHEST, EXCISIONAL BIOPSY:
- SQUAMOUS CELL CARCINOMA IN SITU (BOWEN'S DISEASE), COMPLETELY EXCISED.
- SOLAR ELASTOSIS, MILD.

Micro

The sections show hair bearing skin. The squamous epithelium has full thickness changes including an increased nuclear-cytoplasmic ratio, loss of polarity, and nuclear hyperchromasia. Mitoses are seen in the upper third of the epithelium. Nucleoli are not apparent. No atypical cells are seen in the dermis. Parakeratosis overlies the abnormal keratinocytes. Solar elastosis is present. No melanocytic nests are identified.

Alternate

The sections show hair bearing skin. The squamous epithelium has full thickness changes including increased nuclear-cytoplasmic ratio, nuclear enlargement, loss of polarity, and nuclear hyperchromasia. Mitotic figures are easily identified.

No atypical cells are seen in the dermis; however, the epidermis is thickened. The dermal epidermal interface has a smooth contour. No paradoxical differentiation is identified. Inflammation at the dermal epidermal junction is minimal. Parakeratosis overlies the normal keratinocytes. The lesion is completely excised in the plane of section. Dermal scarring is present.

See also

• Dermatologic neoplasms.
• Squamous cell carcinoma.