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| ==Epidermal inclusion cyst== | | ==Epidermal inclusion cyst== |
| *Abbreviated ''EIC''.
| | {{Main|Epidermal inclusion cyst}} |
| *[[AKA]] ''epidermal cyst''.
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| *[[AKA]] ''epidermoid cyst''.<ref name=Ref_Derm302>{{Ref Derm|302}}</ref>
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| *[[AKA]] ''follicular cyst, infundibular type''.
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| ===General===
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| *Very common.
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| *The clinical term is ''[[sebaceous cyst]]''.
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| **This is a misnomer as they contain keratin (not sebum).<ref name=dermis36946>URL: [http://www.dermis.net/dermisroot/en/36946/diagnose.htm http://www.dermis.net/dermisroot/en/36946/diagnose.htm]. Accessed on: 2 November 2012.</ref><ref name=pmid18201468>{{Cite journal | last1 = Venus | first1 = MR. | last2 = Eltigani | first2 = EA. | last3 = Fagan | first3 = JM. | title = Just another sebaceous cyst? | journal = Ann R Coll Surg Engl | volume = 89 | issue = 6 | pages = W19-21 | month = Sep | year = 2007 | doi = 10.1308/147870807X227791 | PMID = 18201468 | PMC = 2121251 }}.</ref>
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| **The term may be used to refer to a [[pilar cyst]].
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| ===Gross===
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| Features:<ref>URL: [http://dermatlas.med.jhmi.edu/derm/result.cfm?diagnosis=128 http://dermatlas.med.jhmi.edu/derm/result.cfm?diagnosis=128]. Accessed on: 2 November 2012.</ref>
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| *[[Nodule]].
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| *+/-Yellowish colour.
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| DDx:
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| *[[Pilar cyst]] - indistinguishable on gross.<ref name=dermis36946>URL: [http://www.dermis.net/dermisroot/en/36946/diagnose.htm http://www.dermis.net/dermisroot/en/36946/diagnose.htm]. Accessed on: 2 November 2012.</ref>
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| *[[Melanoma]].<ref name=pmid18201468/>
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| ====Image====
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| <gallery>
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| Image:Inflamed_epidermal_inclusion_cyst.jpg |Epidermal inclusion cyst. (WC)
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| </gallery>
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| ===Microscopic===
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| Features:
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| *Cyst lining has a granular layer - '''key feature'''.<ref>URL: [http://emedicine.medscape.com/article/1058907-diagnosis http://emedicine.medscape.com/article/1058907-diagnosis]. Accessed on: 18 March 2011.</ref>
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| *Trapped collagen bundles at edge of lesion with surrounded by fibroblasts.
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| *Keratin.
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| *+/-[[granuloma|Granulomatous inflammation]] due to rupture.
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| DDx:
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| *[[Pilar cyst]] - no granular layer.
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| *[[Eccrine hidrocystoma]] - eyelid lesion; same histology.<ref name=pmid10065300>{{Cite journal | last1 = Adams | first1 = SP. | title = Dermacase. Eccrine hydrocystoma. | journal = Can Fam Physician | volume = 45 | issue = | pages = 297, 306 | month = Feb | year = 1999 | doi = | PMID = 10065300 |PMC = 2328272 }}</ref>
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| *[[Dermoid cyst]] - has adnexal structures, i.e. hair follicle, sebaceous glands, sweat glands.
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| *Cystic [[squamous cell carcinoma of the skin|squamous cell carcinoma]].<ref name=pmid12079164>{{Cite journal | last1 = Lin | first1 = CY. | last2 = Jwo | first2 = SC. | title = Squamous cell carcinoma arising in an epidermal inclusion cyst. | journal = Chang Gung Med J | volume = 25 | issue = 4 | pages = 279-82 | month = Apr | year = 2002 | doi = | PMID = 12079164 }}</ref>
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| *[[Keratoacanthoma]].<ref name=Ref_Derm302>{{Ref Derm|302}}</ref>
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| *[[Dermatofibrosarcoma protuberans]] - if lesion is large.
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| *Hybrid epidermoid and trichilemmal cyst.<ref name=pmid6643785>{{Cite journal | last1 = Brownstein | first1 = MH. | title = Hybrid cyst: a combined epidermoid and trichilemmal cyst. | journal = J Am Acad Dermatol | volume = 9 | issue = 6 | pages = 872-5 | month = Dec | year = 1983 | doi = | PMID = 6643785 }}</ref>
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| ====Images====
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| www:
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| *[http://www.flickr.com/photos/euthman/5517587941/in/photostream/ Epidermal inclusion cyst (flickr.com)].
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| *[http://www.ajronline.org/content/184/3_supp/S47/F4.expansion.html Epidermal inclusion cyst (ajronline.org)].<ref name=pmid15728019>{{Cite journal | last1 = Crystal | first1 = P. | last2 = Shaco-Levy | first2 = R. | title = Concentric rings within a breast mass on sonography: lamellated keratin in an epidermal inclusion cyst. | journal = AJR Am J Roentgenol | volume = 184 | issue = 3 Suppl | pages = S47-8 | month = Mar | year = 2005 | doi = | PMID = 15728019 |URL = http://www.ajronline.org/cgi/pmidlookup?view=long&pmid=15728019}}</ref>
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| *[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2627164/figure/F1/ Ruptured epidermal inclusion cyst (nih.gov)].
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| ===Sign out===
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| <pre>
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| SKIN CYST, BACK, EXCISION:
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| - EPIDERMAL INCLUSION CYST.
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| </pre>
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| ====Ruptured====
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| <pre>
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| SKIN LESION, RIGHT CHEEK, EXCISION:
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| - RUPTURED EPIDERMAL INCLUSION CYST.
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| </pre>
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| ====Micro====
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| 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.
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| =====Ruptured=====
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| 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.
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| 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.
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| =====Ruptured without epithelium=====
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| 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.
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| ==Pilar cyst== | | ==Pilar cyst== |