Dermal cysts

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

Cysts

Common types:[1]

Epidermal necrosis

Venous lake

General

  • Dilated vein.

Microscopic

Features:[2]

  • Lined by endothelium.
  • Blood in lumen.
  • +/-Fibrin in lumen.

DDx:

  • Angiokeratoma.
    • Ectatic superficial dermal vessels.
    • Irregular acanthosis.
    • Longer rete ridges.

Epidermal inclusion cyst

  • AKA epidermal cyst.

General

  • Very common.

Microscopic

Features:

  • Cyst lining has a granular layer - key feature.[3]
  • Trapped collagen bundles at edge of lesion with surrounded by fibroblasts.
  • Keratin.

Image:

DDx:

Pilar cyst

  • AKA trichilemmal cyst.

General

  • Very common.

Gross

  • Classic location: head ~90%.[6]

Microscopic

Features:

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

DDx:

Images:

Steatocystoma

General

  • Benign.
  • Typically adults.
  • Usually on the trunk.
  • May be genetic; known as steatocystoma multiplex.[7]
    • Classically autosomal dominant.[8]

Microscopic

Features:[9]

  • Cyst lined by squamous epithelium with:
    1. Corrugated eosinophilic lining - key feature.
      • Similar appearance to compact keratin (hyperkeratosis).
      • Described as a hyaline cuticle.[10]
    2. No granular cell layer.

Images:

Dermoid cyst

General

Microscopic

Features:[12][13]

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

DDx:

Images:

Digital mucous cyst

General

  • Dome-shaped papule.

Microscopic

Features:[14]

  • 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".[15][16]

DDx:

Images:

See also

References

  1. TN07 D5
  2. Weedon's Skin Pathology. 3rd Ed. P.895.
  3. URL: http://emedicine.medscape.com/article/1058907-diagnosis. Accessed on: 18 March 2011.
  4. 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.
  5. 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/.
  6. URL: http://emedicine.medscape.com/article/1058907-overview. Accessed on: 15 April 2012.
  7. Online 'Mendelian Inheritance in Man' (OMIM) 184500
  8. URL: http://path.upmc.edu/cases/case674/dx.html. Accessed on: 29 January 2012.
  9. Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 312. ISBN 978-0443066542.
  10. URL: http://path.upmc.edu/cases/case674/dx.html. Accessed on: 29 January 2012.
  11. URL: http://path.upmc.edu/cases/case674.html. Accessed on: 29 January 2012.
  12. 12.0 12.1 12.2 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.
  13. 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.
  14. 14.0 14.1 URL: http://www.dermpedia.org/dermpedia-textbook/digital-mucous-myxoid-cyst. Accessed on: 17 January 2012.
  15. URL: http://dictionary.reference.com/browse/mucous. Accessed on: 8 January 2012.
  16. URL: http://dictionary.reference.com/browse/mucus. Accessed on: 8 January 2012.