Dark skin focalities: Difference between revisions

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Pattern recognition: Junctional nevus
Mikael Häggström (talk | contribs)
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===Pattern recognition===
===Pattern recognition===
<gallery>
<gallery>
File:Histopathology of melanocytic nevus.jpg|link=Melanocytic nevus|[[Junctional nevus]]
File:Histopathology of melanocytic nevus.jpg|link=Junctional nevus|[[Junctional nevus]]
File:Histopathology of melanoma, HE.jpg|link=Melanoma|[[Melanoma]]
File:Histopathology of melanoma, HE.jpg|link=Melanoma|[[Melanoma]]
File:Blue nevus (4 of 4) (2797064219).jpg|link=Blue nevus|[[Blue nevus]]
File:Blue nevus (4 of 4) (2797064219).jpg|link=Blue nevus|[[Blue nevus]]
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|-
|-
! Junction between epidermis and dermis
! Junction between epidermis and dermis
| [[Junctional nevus]] || [[Melanoma in situ]]
| [[File:Histopathology of melanocytic nevus.jpg|link=Junctional nevus|200px|center]] [[Junctional nevus]] || [[File:Histopathology of lentigo maligna.jpg|200px|center|link=Melanoma in situ]] [[Melanoma in situ]]
|-
|-
! Dermis
! Dermis
| [[Dermal nevus]] || [[Invasive melanoma of the skin|Invasive melanoma]]
| [[File:Histopathology of dermal nevus, high magnification.jpg|200px|center|link=Dermal nevus]] [[Dermal nevus]] || [[File:Histopathology of nodular melanoma, high magnification.jpg|200px|center|link=Invasive melanoma of the skin]] [[Invasive melanoma of the skin|Invasive melanoma]]
|}
|}
{{Bottom}}
{{Bottom}}

Revision as of 16:11, 1 September 2020

Author: Mikael Häggström [note 1]

Dark skin focalities (in this case, from top left and clockwise: Spitz nevus, seborrheic keratosis, elevated melanocytic nevus and melanoma)

Skin with one or more areas that are darker than the surroundings. They are part of suspected malignant skin excisions.

Fixation

Generally 10% neutral buffered formalin.

  See also: General notes on fixation


Gross processing of skin excisions

Gross pathologic processing of skin excisions[1][note 2]
Lesion size
<4 mm 4 - 8 mm 9 - 15 mm
Benign appearance

File:Tissue selection from skin excision with lesion less than 4 mm with benign appearance.png

File:Tissue selection from skin excision with lesion 4-8 mm with benign appearance.png

File:Tissue selection from skin excision with lesion 9-15 mm with benign appearance.png

Suspected malignancy File:Tissue selection from skin excision less than 4 mm with suspected malignant lesion.png File:Tissue selection from skin excision 4-8 mm with suspected malignant lesion.png File:Tissue selection from skin excision 9-15 mm with 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

File:Pie chart of incidence and malignancy of pigmented skin lesions.png
Various diagnoses of pigmented skin lesions, by relative incidence upon biopsy, and malignancy potential.

Evaluation is largely based on the relative incidence and malignancy of various differential diagnoses (see pie chart). Main approaches are:

  • Direct pattern recognition
  • Systematic

Either way can be done by scrolling through the epidermis at intermediate magnification and then through the dermis at a lower magnification.

Pattern recognition

Systematic

One approach for the most common conditions are:

Atypia and/or dysplasia
Low High
Junction between epidermis and dermis
File:Histopathology of melanocytic nevus.jpg
Junctional nevus
File:Histopathology of lentigo maligna.jpg
Melanoma in situ
Dermis
File:Histopathology of dermal nevus, high magnification.jpg
Dermal nevus
File:Histopathology of nodular melanoma, high magnification.jpg
Invasive melanoma

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 examples show a normal mole (upper row, benign appearance) and a superficial basal cell carcinoma (lower row, suspected malignancy).

Main page

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.

Image sources