Basal-cell carcinoma

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Author: Mikael Häggström [notes 1]

Nodular basal-cell carcinoma.

Basal-cell carcinoma (BCC):

Fixation

Generally 10% neutral buffered formalin.

See also: General notes on fixation

Gross processing

Gross examination

Note:

  • Color
  • Well-defined or diffuse border
  • Size
  • Any elevation

Tissue selection

Tissue selection from suspected malignant skin lesions, by lesion size:[1][notes 2]
<4 mm 4 - 8 mm 9 - 15 mm
Tissue selection from skin excision with less than 4 mm suspected malignant lesion.png Tissue selection from skin excision with 4-8 mm suspected malignant lesion.png Tissue selection from skin excision with 9-15 mm suspected malignant lesion.png

In table above, each top image shows recommended lines for cutting out slices to be submitted for further processing. Bottom image shows which side of the slice that should be put to microtomy. Dashed lines here mean that either side could be used.

Further information: Gross processing of skin excisions

Microscopic evaluation

Broadly consists of determining the following:

  • Whether it is basal-cell carcinoma or a differential diagnosis.
  • Aggressiveness pattern
  • Radicality

Optionally, further subtyping of basal-cell carcinoma can be made.

Characteristics

Cells appearing similar to epidermal basal cells, and are usually well differentiated.[2]

In uncertain cases, immunohistochemistry using BerEP4 can be used, having a high sensitivity and specificity in detecting only BCC cells.[3]

Differential diagnoses

Main histological differential diagnoses of basal cell carcinoma:[4]
Differential diagnosis Pathological Features Image
Trichoblastoma Absence of cleft, rudimentary hair germs, papillary mesenchymal bodies. Micrographs of trichoblastoma.jpg
Adenoid cystic carcinoma Lack of basaloid cells disposed in peripheral palisades; adenoid-cystic lesion without connection to the epidermis; absence of artefactual clefts Micrograph of adenoid cystic carcinoma.jpg
Microcystic adnexal carcinoma Bland keratinocytes, keratin cysts, ductal differentiation. BerEp4- (in 60% of cases)[5], CEA+, EMA+
Trichoepithelioma[notes 3] Rims of collagen bundles, calcification, follicular/sebaceous/infundibular differentiation and cut artefacts. Cytokeratin (CK)20+, p75+, Pleckstrin homology-like domain family A member 1 + (PHLDA1+), common acute lymphoblastic leukemiaantigen + (CD10+) in tumor stroma, CK 6-, Ki-67- and Androgen Rceptor- (AR-) Trichoepithelioma (1338537528).jpg
Merkel cell carcinoma Cells arranged in a diffuse, trabecular and/or nested pattern, involving also the subcutis. Mouse Anti-Cytokeratin (CAM) 5.2+, CK20+, S100-, human leukocyte common antigen- ( LCA-), thyroid transcription factor 1- (TTF1-) Micrographs of a typical merkel cell carcinoma.jpg

Aggressiveness

There are mainly three patterns of aggressiveness, based mainly the cohesion of cancer cells:

Low-level aggressive pattern Moderately aggressive pattern Highly aggressive pattern

Radicality

Determine if there are basal-cell formations continuous with resection margins, or if they are closer or farther than 1 mm from the closest edge.[7] If closer, measure the distance.

If uncertain, immunohistochemistry with BerEP4 helps in distinguishing the BCC cells.

Comparison H&E stain (left) with BerEP4 immunohistochemistry staining (right) on a pathological section having BCC with squamous cell metaplasia. Only BCC cells are stained with BerEP4.[3]

Optionally: Further subtyping

At least, attempt to suggest or exclude morpheaform (also known as "cicatricial" or "morphoeic") basal-cell carcinoma, since it is more aggressive.

Morpheaform basal-cell carcinoma.
Morpheaform basal-cell carcinoma

It has narrow strands and nests of basaloid cells, surrounded by dense sclerotic stroma.[8]

Nodular basal-cell carcinoma

Nodular basal-cell carcinoma (also known as "classic basal-cell carcinoma") accounts for 50% of all BCC.[4]

It has aggregates of basaloid cells with well-defined borders, showing:[4]

Central necrosis with eosinophilic, granular features may be also present, as well as mucin. The heavy aggregates of mucin determine a cystic structure. Calcification may be also present, especially in long-standing lesions.[4] Mitotic activity is usually not so evident, but a high mitotic rate may be present in more aggressive lesions.[4] Adenoidal BCC can be classified as a variant of the nodular subtype, characterized by basaloid cells with a reticulated configuration extending into the dermis.[4]

Further information: Evaluation of tumors

Reporting

  • Aggressiveness pattern if possible
  • Radicality, mainly into either of the following: edit
  • >1 mm (as per Radicality above): "Clear margins".[notes 4]
  • <1 mm but not continuous with edge: "Close margins at __ mm at (location)[notes 5]." Numbers are generally given at an exactness of 0.1 mm.[7]
  • Continuous with margin: "Not radically excised at (location)[notes 5]."

Optionally, subtype of basal-cell carcinoma

Example:

Non-radical basal-cell cancer.jpg
(Stratified squamous keratinized epithelium, where the dermis contains) moderately aggressive basal-cell carcinoma, not radically excised at the right margin.[notes 6]
See also: General notes on reporting

Notes

  1. For a full list of contributors, see article history. Creators of images are attributed at the image description pages, seen by clicking on the images. See Patholines:Authorship for details.
  2. The excision example shows a superficial basal cell carcinoma.
  3. Desmoplastic tricoepithelioma is particularly similar to basal-cell carcinoma.
  4. A more comprehensive report may state "Clear margins at over __ mm" or the value thereof if it has been measured more exactly.
  5. 5.0 5.1 Locations are mainly the deep edge, or the (superior/inferior/medial/lateral) radial edge.
  6. The direction was known from needle marking.

References

  1. There are many variants for the processing of skin excisions. These examples use aspects from the following sources: ". Ochsner J 5 (2): 22–33. 2003. PMID 22826680. PMC: 3399331. Archived from the original. . 
    - With a "standard histologic examination" that, in addition to the lesion, only includes one section from each side along the longest diameter of the specimen.
    - It also shows an example of circular coverage, with equal coverage distance in all four directions.
    - The entire specimen may be submitted if the risk of malignancy is high.
  2. Robert S Bader. Which histologic findings are characteristic of basal cell carcinoma (BCC)?. Medscape. Updated: Feb 21, 2019
  3. 3.0 3.1 Sunjaya, Anthony Paulo; Sunjaya, Angela Felicia; Tan, Sukmawati Tansil (2017). "The Use of BEREP4 Immunohistochemistry Staining for Detection of Basal Cell Carcinoma ". Journal of Skin Cancer 2017: 1–10. doi:10.1155/2017/2692604. ISSN 2090-2905. 
  4. 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 Paolino, Giovanni; Donati, Michele; Didona, Dario; Mercuri, Santo; Cantisani, Carmen (2017). "Histology of Non-Melanoma Skin Cancers: An Update ". Biomedicines 5 (4): 71. doi:10.3390/biomedicines5040071. ISSN 2227-9059. 
  5. Inskip, Mike; Magee, Jill (2015). "Microcystic adnexal carcinoma of the cheek—a case report with dermatoscopy and dermatopathology ". Dermatology Practical & Conceptual 5 (1). doi:10.5826/dpc.0501a07. ISSN 21609381. 
  6. Yonan, Yousif; Maly, Connor; DiCaudo, David; Mangold, Aaron; Pittelkow, Mark; Swanson, David (2019). "Dermoscopic Description of Fibroepithelioma of Pinkus with Negative Network ". Dermatology Practical & Conceptual: 246–247. doi:10.5826/dpc.0903a23. ISSN 2160-9381.  Creative Commons Attribution License
  7. 7.0 7.1 David Slater, Paul Barrett. Standards and datasets for reporting cancers - Dataset for histopathological reporting of primary cutaneous basal cell carcinoma. The Royal College of Pathologists. February 2019
  8. East, Ellen; Fullen, Douglas R.; Arps, David; Patel, Rajiv M.; Palanisamy, Nallasivam; Carskadon, Shannon; Harms, Paul W. (2016). "Morpheaform Basal Cell Carcinomas With Areas of Predominantly Single-Cell Pattern of Infiltration ". The American Journal of Dermatopathology 38 (10): 744–750. doi:10.1097/DAD.0000000000000541. ISSN 0193-1091.