Dermal cysts

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

Overview

Common types:[1]

Epidermal necrosis

Common cysts

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 as they contain keratin (not sebum).[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.

Images:

DDx:

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

SKIN LESION, RIGHT CHEEK, EXCISION:
- RUPTURED 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 sections show hair-bearing skin with a cyst that is lined by squamous epithelium with a granular layer. The cyst contains keratin. A mixed inflammatory infiltrate (predominantly lymphocytes and plasma cells) surround the cyst. Neutrophils infiltrate the cyst lining and are admixed with the keratin within its core.

The lesion appears to be completely excised in the plane of section. Hair follicles are adjacent to the lesion; however, they are not inflamed. The overlying epithelium is unremarkable.

Ruptured without epithelium

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:[16]

  • Keratin.
  • Cyst lining:
    • Has no granular layer - key feature.
      • Keratohyaline granules (as seen in the granular layer) may be seen focally.
    • Inner most cyst lining cells are large cells with abundant eosinophilic cytoplasm.

DDx:

Images:

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

Micro

The sections show a cyst that is lined by squamous epithelium without a granular layer. Focally, keratohyaline granules are seen in the cyst lining cells. The innermost cyst lining cells are large and have abundant eosinophilic cytoplasm. The cyst contains keratin.

Dermoid cyst

General

Microscopic

Features:[17][18]

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

DDx:

Images:

Pilonidal cyst

General

  • Benign.
  • Young adults (late teens, early twenties) - usu. men.[20]

Gross

  • Usually at gluteal folds.
    • Uncommon: axilla, genital region, umbilicus, scalp.[21]

Microscopic

Features:[21]

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.

Less common

Steatocystoma

General

  • Benign.
  • Typically adults.
  • Usually on the trunk.
  • May be genetic; known as steatocystoma multiplex.[23]
    • Classically autosomal dominant.[24]

Microscopic

Features:[25]

  • Cyst lined by squamous epithelium with:
    1. Corrugated eosinophilic lining - key feature.
      • Similar appearance to compact keratin (hyperkeratosis).
      • Described as a hyaline cuticle.[26]
    2. No granular cell layer.

Images:

Digital mucous cyst

General

Microscopic

Features:[28]

  • 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".[29][30]

DDx:

Images:

Apocrine cystadenoma

General

  • Uncommon.

Microscopic

Features:[31]

  • Multiloculated.
  • Solid areas of epithelial proliferation.
    • Apocrine - columnar epithelium +/- apical snouts.

Images:

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. ↑ Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 309. ISBN 978-0443066542.
  17. ↑ 17.0 17.1 17.2 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.
  18. ↑ 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.
  19. ↑ URL: http://emedicine.medscape.com/article/788127-overview. Accessed on: 10 September 2012.
  20. ↑ URL: http://www.nhs.uk/conditions/Pilonidal-sinus/Pages/Introduction.aspx. Accessed on: 10 September 2012.
  21. ↑ 21.0 21.1 Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 326. ISBN 978-0443066542.
  22. ↑ 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.
  23. ↑ Online 'Mendelian Inheritance in Man' (OMIM) 184500
  24. ↑ URL: http://path.upmc.edu/cases/case674/dx.html. Accessed on: 29 January 2012.
  25. ↑ Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 312. ISBN 978-0443066542.
  26. ↑ URL: http://path.upmc.edu/cases/case674/dx.html. Accessed on: 29 January 2012.
  27. ↑ URL: http://path.upmc.edu/cases/case674.html. Accessed on: 29 January 2012.
  28. ↑ 28.0 28.1 URL: http://www.dermpedia.org/dermpedia-textbook/digital-mucous-myxoid-cyst. Accessed on: 17 January 2012.
  29. ↑ URL: http://dictionary.reference.com/browse/mucous. Accessed on: 8 January 2012.
  30. ↑ URL: http://dictionary.reference.com/browse/mucus. Accessed on: 8 January 2012.
  31. ↑ Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 316. ISBN 978-0443066542.
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