Epidermoid cyst: Difference between revisions

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==Microscopic evaluation==
==Microscopic evaluation==
[[File:Histopathology of epidermoid cyst.jpg|thumb|Epidermoid cyst]]
[[File:Histopathology of epidermoid cyst.jpg|thumb|Epidermoid cyst]]
[[File:Histopathology of ruptured epidermoid cyst.jpg|thumb|A '''ruptured epidermoid cyst''', with a foreign body reaction including multinucleated giant cells, surrounding keratin fragments. A cyst wall is not necessary for diagnosis in a clinical context of skin cyst.]]
Typical findings:<ref>{{cite web|url=http://www.pathologyoutlines.com/topic/skintumornonmelanocytickeratinouscystepidermal.html|title=Skin nonmelanocytic tumor - Cysts - Epidermal (epidermoid) type|author= V. Claire Vaughan, M.D., Joshua Wisell, M.D.|website=pathology Outlines}} Topic Completed: 9 May 2019. Revised: 13 December 2019</ref>
Typical findings:<ref>{{cite web|url=http://www.pathologyoutlines.com/topic/skintumornonmelanocytickeratinouscystepidermal.html|title=Skin nonmelanocytic tumor - Cysts - Epidermal (epidermoid) type|author= V. Claire Vaughan, M.D., Joshua Wisell, M.D.|website=pathology Outlines}} Topic Completed: 9 May 2019. Revised: 13 December 2019</ref>
*Stratified squamous epithelium with a granular layer
*Stratified squamous epithelium with a granular layer
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===Differential diagnosis===
===Differential diagnosis===
 
Mainly:
====Pilomatricoma====
<gallery mode=packed heights=200>
[[File:Histopathology of pilomatricoma, high magnification, annotated.jpg|thumb|240px|Histopathology of pilomatricoma, high magnification, H&E stain, showing the characteristic components.]]
File:Histopathology of trichilemmal cyst - annotated.jpg|'''Trichilemmal cyst''', containing, from external (top) to internal (bottom):{{MH}}<ref>{{cite web|url=https://www.medscape.com/answers/1058907-121502/which-histologic-findings-are-characteristic-of-trichilemmal-cyst-pilar-cyst|title=Which histologic findings are characteristic of trichilemmal cyst (pilar cyst)?|author=Anne Elizabeth Laumann|website=Medscape}} Updated: Jun 11, 2020,</ref><br>- Fibrous capsule<br>- Small, cuboidal, dark-staining basal epithelial cells in a palisade arrangement, with no distinct intercellular bridging<br>- Swollen pale keratinocytes, which increase in height closer to the interior<br>- Solid eosinophilic-staining keratin <br>There is no granular cell layer (in contrast to an epidermoid cyst).
The characteristic components of a pilomatricoma include a ''stroma'' of fibrovascular connective tissue
File:Histopathology of pilomatricoma, high magnification, annotated.jpg|'''[[Pilomatricoma]]''': ''Stroma'' surrounding irregularly shaped islands containing ''basaloid cells'' (darkly stained, round or elongated), which abruptly or gradually transitions into ''ghost cells'' (having pale cytoplasm and a central clear area), which in turn may transition into ''necrosis''.{{MH}}<ref name=atlas>{{cite web|url=http://atlasgeneticsoncology.org/Tumors/PilomatricomaID5153.html|title=Skin: Pilomatricoma|website=Atlas of Genetics and Cytogenetics in Oncology and Haematology|date=2009-06-01|author=Punnya V Angadi}}</ref>
surrounding irregularly shaped, lobulated islands containing ''basaloid cells'' (being darkly stained, round or elongated, with indistinct cell borders and minimal cytoplasm, with nuclei being round to ovoid, deeply basophilic and generally prominent nucleoli), which abruptly or gradually transitions into ''ghost cells'' (having abundant, pale, eosinophilic cytoplasm, well defined cell borders and a central clear area, but only only faint traces of nuclear material), which in turn may transition into keratinaceous to amorphous ''necrosis''.<ref name=atlas>{{cite web|url=http://atlasgeneticsoncology.org/Tumors/PilomatricomaID5153.html|title=Skin: Pilomatricoma|website=Atlas of Genetics and Cytogenetics in Oncology and Haematology|date=2009-06-01|author=Punnya V Angadi}}</ref>
</gallery>
 
{{Further|Skin cyst}}
The presence of calcifications with foreign body giant cells is common within pilomatricomas.<ref>{{cite book |editor1-first=David E. |editor1-last=Elder |editor2-first=Bernett L. |editor2-last=Johnson |editor3-first=Rosalie |editor3-last=Elenitsas |year=2005 |title=Lever's Histopathology of the Skin |publisher=Lippincott Williams & Wilkins |isbn=978-0-7817-3742-5 }}{{page needed|date=July 2016}}</ref>
 
====Trichilemmal cyst====
[[File:Histopathology of trichilemmal cyst - annotated.jpg|thumb|Trichilemmal cyst.]]
The constitution of a trichilemmal cyst (also called pilar cyst), from external (top) to internal (bottom):<ref>{{cite web|url=https://www.medscape.com/answers/1058907-121502/which-histologic-findings-are-characteristic-of-trichilemmal-cyst-pilar-cyst|title=Which histologic findings are characteristic of trichilemmal cyst (pilar cyst)?|author=Anne Elizabeth Laumann|website=Medscape}} Updated: Jun 11, 2020,</ref>
*Fibrous capsule
*Small, cuboidal, dark-staining basal epithelial cells in a palisade arrangement, with no distinct intercellular bridging
*Swollen pale keratinocytes, which increase in height closer to the interior
*Solid eosinophilic-staining keratin  
There is no granular cell layer (in contrast to an epidermoid cyst).


===Further workup===
===Further workup===

Latest revision as of 08:42, 27 September 2021

Author: Mikael Häggström [note 1]
Generally presents as a skin cyst. Also known as epidermal inclusion cyst (EIC) and sebaceous cyst.

Microscopic evaluation

Epidermoid cyst
A ruptured epidermoid cyst, with a foreign body reaction including multinucleated giant cells, surrounding keratin fragments. A cyst wall is not necessary for diagnosis in a clinical context of skin cyst.

Typical findings:[1]

  • Stratified squamous epithelium with a granular layer
  • Cyst wall does not contain eccrine glands, sebaceous glands or hair follicles
  • Abundant keratin flakes in cyst lumen
  • Often giant cell granuloma in ruptured cysts, similar to foreign body granuloma

Differential diagnosis

Mainly:

  • Trichilemmal cyst, containing, from external (top) to internal (bottom):[image 1][2] - Fibrous capsule - Small, cuboidal, dark-staining basal epithelial cells in a palisade arrangement, with no distinct intercellular bridging - Swollen pale keratinocytes, which increase in height closer to the interior - Solid eosinophilic-staining keratin There is no granular cell layer (in contrast to an epidermoid cyst).
    Trichilemmal cyst, containing, from external (top) to internal (bottom):[image 1][2]
    - Fibrous capsule
    - Small, cuboidal, dark-staining basal epithelial cells in a palisade arrangement, with no distinct intercellular bridging
    - Swollen pale keratinocytes, which increase in height closer to the interior
    - Solid eosinophilic-staining keratin
    There is no granular cell layer (in contrast to an epidermoid cyst).
  • Pilomatricoma: Stroma surrounding irregularly shaped islands containing basaloid cells (darkly stained, round or elongated), which abruptly or gradually transitions into ghost cells (having pale cytoplasm and a central clear area), which in turn may transition into necrosis.[image 1][3]
    Pilomatricoma: Stroma surrounding irregularly shaped islands containing basaloid cells (darkly stained, round or elongated), which abruptly or gradually transitions into ghost cells (having pale cytoplasm and a central clear area), which in turn may transition into necrosis.[image 1][3]

Further information: Skin cyst

Further workup

Look for signs of cyst rupture, which may manifest as inflammation, including granulomas and microabscesses.

Microscopic report

Example:

Scalp skin cyst, excision:
Ruptured epidermoid cyst.

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.

Main page

References

  1. ↑ V. Claire Vaughan, M.D., Joshua Wisell, M.D.. Skin nonmelanocytic tumor - Cysts - Epidermal (epidermoid) type. pathology Outlines. Topic Completed: 9 May 2019. Revised: 13 December 2019
  2. ↑ Anne Elizabeth Laumann. Which histologic findings are characteristic of trichilemmal cyst (pilar cyst)?. Medscape. Updated: Jun 11, 2020,
  3. ↑ Punnya V Angadi (2009-06-01). Skin: Pilomatricoma. Atlas of Genetics and Cytogenetics in Oncology and Haematology.

Image sources

  1. ↑ 1.0 1.1 Image(s) by: Mikael Häggström, M.D. Public Domain
    - Author info
    - Reusing images
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