Dark skin focalities: Difference between revisions

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Microscopic evaluation: General technique
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==Microscopic evaluation==
==Microscopic evaluation==
[[File:Pie chart of incidence and malignancy of pigmented skin lesions.png|thumb|370px|Various diagnoses of pigmented skin lesions, by relative incidence upon biopsy, and malignancy potential.]]
[[File:Pie chart of incidence and malignancy of pigmented skin lesions.png|thumb|370px|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.
===Melanocytic lesions===
Scrolling through the epidermis at intermediate magnification and then through the dermis at a lower magnification.


===Pattern recognition===
Melanocytic lesions (including nevus) are the most common, and can be classified as follows:
<gallery>
{|class="wikitable"
File:Histopathology of melanocytic nevus.jpg|link=Melanocytic nevus|[[Melanocytic nevus]]
!  !!colspan=2| Atypia and/or dysplasia
File:Histopathology of melanoma, HE.jpg|link=Melanoma|[[Melanoma]]
|-
File:Blue nevus (4 of 4) (2797064219).jpg|link=Blue nevus|[[Blue nevus]]
!  !! Low !! High
|-
! Junction<br>between<br>epidermis<br>and dermis
| [[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
| [[File:Histopathology of dermal nevus, high magnification.jpg|160px|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]]'''
|}
A '''compound nevus''' consists of both junctional and dermal melanocytic nevus nests.
 
===Non-melanocytic===
<gallery mode=packed heights=180>
File:Histopathology of a pigmented basal-cell carcinoma.jpg|Pigmented '''[[basal-cell carcinoma]]''', with palisading cells around nests.
File:Histopathology of seborrheic keratosis.jpg|link=Seborrheic keratosis|[[Seborrheic keratosis]]
File:Histopathology of seborrheic keratosis.jpg|link=Seborrheic keratosis|[[Seborrheic keratosis]]
File:Basal Cell Carcinoma, Nodular Pattern (6032028849).jpg|link=Basal cell carcinoma|[[Basal cell carcinoma]]
</gallery>
</gallery>
===Systematic===
By their relative incidences, one practical approach is:
*Is it a '''[[Dysplastic nevus|dysplastic (melanocytic) nevus]]'''? If not:
*Is it a '''[[Melanoma]]'''? If not:
*Compare to patterns of various other possibilities.
{{Bottom}}
{{Bottom}}

Latest revision as of 20:35, 8 June 2022

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

Suspected malignancy

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

Various diagnoses of pigmented skin lesions, by relative incidence upon biopsy, and malignancy potential.

Melanocytic lesions

Scrolling through the epidermis at intermediate magnification and then through the dermis at a lower magnification.

Melanocytic lesions (including nevus) are the most common, and can be classified as follows:

Atypia and/or dysplasia
Low High
Junction
between
epidermis
and dermis
Junctional nevus
Melanoma in situ
Dermis
Dermal nevus
Invasive melanoma

A compound nevus consists of both junctional and dermal melanocytic nevus nests.

Non-melanocytic

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