Dermal cysts

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Dermal cysts, also skin cysts, are common in dermatopathology. Dermatopathologists can diagnose 'em.

Cysts

Common types:[1]

Epidermal necrosis

Venous lake

General

  • Dilated vein.

Clinical:

  • Blanch with pressure.[2]

Gross

  • Purple/blue spot.

Images:

Microscopic

Features:[4]

  • Lined by endothelium.
  • Blood in lumen.
  • +/-Fibrin in lumen.
  • +/-Solar elastosis - very common.[5]

DDx:

Images:

Epidermal inclusion cyst

  • AKA epidermal cyst.
  • AKA epidermoid cyst.[6]
  • AKA follicular cyst, infundibular type.

General

  • Very common.
  • The clinical term is sebaceous cyst.
    • This is a misnomer they contain keratin.[7][8]
    • The term may be used to refer to a pilar cyst.

Gross

Features:[9]

DDx:

Image:

Microscopic

Features:

  • Cyst lining has a granular layer - key feature.[10]
  • Trapped collagen bundles at edge of lesion with surrounded by fibroblasts.
  • Keratin.
  • +/-Granulomatous inflammation due to rupture.

Image:

DDx:

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SKIN CYST, BACK, EXCISION: 
- EPIDERMAL INCLUSION CYST.

Micro

The sections show hair-bearing skin with a cyst that is lined by squamous epithelium with a granular layer. The cyst contains keratin. The overlying epithelium is unremarkable.

Ruptured

The section shows a dermal collection of neutrophils with acellular keratin-like material surrounded by histiocytes and fibrosis. The lesion is completely excised in the plane of section. Hair follicles are adjacent to the abscess; however, they are not inflamed.

Pilar cyst

  • AKA trichilemmal cyst.

General

  • Very common.

Gross

  • Classic location: head ~90%.[15]

Microscopic

Features:

  • Keratin.
  • Cyst lining has no granular layer - key feature.
  • Trapped collagen bundles at edge of lesion with surrounded by fibroblasts.

DDx:

Images:

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SKIN CYST, LEFT FLANK, EXCISION:
- TRICHILEMMAL CYST (PILAR CYST).

Steatocystoma

General

  • Benign.
  • Typically adults.
  • Usually on the trunk.
  • May be genetic; known as steatocystoma multiplex.[16]
    • Classically autosomal dominant.[17]

Microscopic

Features:[18]

  • Cyst lined by squamous epithelium with:
    1. Corrugated eosinophilic lining - key feature.
      • Similar appearance to compact keratin (hyperkeratosis).
      • Described as a hyaline cuticle.[19]
    2. No granular cell layer.

Images:

Dermoid cyst

General

Microscopic

Features:[21][22]

  • Cyst lined by normal (keratinized) skin with adnexal structure (hair follicles, sweat glands, sebaceous glands).

DDx:

Images:

Digital mucous cyst

General

Microscopic

Features:[23]

  • Mucous in superficial dermis - key feature.
  • No epithelial lining; it is a pseudocyst.

Note:

  • Mucin = glycolated proteins; may be part of mucous.
  • Mucous = slippery secretion.
    • Some split hairs over the "u" - "mucus" vs. "mucous".[24][25]

DDx:

Images:

Pilonidal cyst

General

  • Benign.
  • Young adults (late teens, early twenties) - usu. men.[27]

Gross

  • Usually at gluteal folds.
    • Uncommon: axilla, genital region, umbilicus, scalp.[28]

Microscopic

Features:[28]

DDx:

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SKIN LESION (PILONIDAL SINUS), EXCISION: 
- PILONIDAL SINUS.
- NEGATIVE FOR MALIGNANCY.

Micro

The section shows hair-bearing skin with a deep sinus tract containing large clusters of neutrophils, abundant plasma cells, hemosiderin-laden macrophages, eosinophils and multinucleated giant cells. The core of the lesion is, focally, well-vascularized. At the edge of the lesion is fibrotic tissue with plump fibroblasts. Benign, fibrofatty tissue with scant inflammation completely surrounds the tract, in the plane of section; however, it is focally fragmented. There is no squamous lining within the sinus. No nuclear atypia is identified.

See also

References

  1. ↑ Greenwald, J.; Heng, M. (2007). Toronto Notes for Medical Students 2007 (2007 ed.). The Toronto Notes Inc. for Medical Students Inc.. pp. D5. ISBN 978-0968592878.
  2. ↑ URL: http://dermatlas.med.jhmi.edu/derm/IndexDisplay.cfm?ImageID=-969536424. Accessed on: 13 August 2012.
  3. ↑ 3.0 3.1 3.2 URL: http://dermatlas.med.jhmi.edu/derm/result.cfm?Diagnosis=605386295. Accessed on: 13 August 2012.
  4. ↑ Weedon's Skin Pathology. 3rd Ed. P.895.
  5. ↑ 5.0 5.1 Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 551. ISBN 978-0443066542.
  6. ↑ 6.0 6.1 Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 302. ISBN 978-0443066542.
  7. ↑ 7.0 7.1 URL: http://www.dermis.net/dermisroot/en/36946/diagnose.htm. Accessed on: 2 November 2012.
  8. ↑ 8.0 8.1 Venus, MR.; Eltigani, EA.; Fagan, JM. (Sep 2007). "Just another sebaceous cyst?". Ann R Coll Surg Engl 89 (6): W19-21. doi:10.1308/147870807X227791. PMC 2121251. PMID 18201468. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2121251/..
  9. ↑ URL: http://dermatlas.med.jhmi.edu/derm/result.cfm?diagnosis=128. Accessed on: 2 November 2012.
  10. ↑ URL: http://emedicine.medscape.com/article/1058907-diagnosis. Accessed on: 18 March 2011.
  11. ↑ Crystal, P.; Shaco-Levy, R. (Mar 2005). "Concentric rings within a breast mass on sonography: lamellated keratin in an epidermal inclusion cyst.". AJR Am J Roentgenol 184 (3 Suppl): S47-8. PMID 15728019.
  12. ↑ Adams, SP. (Feb 1999). "Dermacase. Eccrine hydrocystoma.". Can Fam Physician 45: 297, 306. PMC 2328272. PMID 10065300. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2328272/.
  13. ↑ Lin, CY.; Jwo, SC. (Apr 2002). "Squamous cell carcinoma arising in an epidermal inclusion cyst.". Chang Gung Med J 25 (4): 279-82. PMID 12079164.
  14. ↑ Brownstein, MH. (Dec 1983). "Hybrid cyst: a combined epidermoid and trichilemmal cyst.". J Am Acad Dermatol 9 (6): 872-5. PMID 6643785.
  15. ↑ URL: http://emedicine.medscape.com/article/1058907-overview. Accessed on: 15 April 2012.
  16. ↑ Online 'Mendelian Inheritance in Man' (OMIM) 184500
  17. ↑ URL: http://path.upmc.edu/cases/case674/dx.html. Accessed on: 29 January 2012.
  18. ↑ Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 312. ISBN 978-0443066542.
  19. ↑ URL: http://path.upmc.edu/cases/case674/dx.html. Accessed on: 29 January 2012.
  20. ↑ URL: http://path.upmc.edu/cases/case674.html. Accessed on: 29 January 2012.
  21. ↑ 21.0 21.1 21.2 Gandhi N, Syed NA, Alen R. Dermoid Cyst. EyeRounds.org. posted July 26, 2010; Available from: http://www.EyeRounds.org/cases/115-dermoid-cyst.htm. Accessed on: 22 September 2011.
  22. ↑ Mitchell, Richard; Kumar, Vinay; Fausto, Nelson; Abbas, Abul K.; Aster, Jon (2011). Pocket Companion to Robbins & Cotran Pathologic Basis of Disease (8th ed.). Elsevier Saunders. pp. 596. ISBN 978-1416054542.
  23. ↑ 23.0 23.1 URL: http://www.dermpedia.org/dermpedia-textbook/digital-mucous-myxoid-cyst. Accessed on: 17 January 2012.
  24. ↑ URL: http://dictionary.reference.com/browse/mucous. Accessed on: 8 January 2012.
  25. ↑ URL: http://dictionary.reference.com/browse/mucus. Accessed on: 8 January 2012.
  26. ↑ URL: http://emedicine.medscape.com/article/788127-overview. Accessed on: 10 September 2012.
  27. ↑ URL: http://www.nhs.uk/conditions/Pilonidal-sinus/Pages/Introduction.aspx. Accessed on: 10 September 2012.
  28. ↑ 28.0 28.1 Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 326. ISBN 978-0443066542.
  29. ↑ Chatzis, I.; Noussios, G.; Katsourakis, A.; Chatzitheoklitos, E.. "Squamous cell carcinoma related to long standing pilonidal-disease.". Eur J Dermatol 19 (4): 408-9. doi:10.1684/ejd.2009.0705. PMID 19482585.
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