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#redirect [[Melanocytic_lesions#Clark_nevus]]
{{ Infobox diagnosis
| Name      = {{PAGENAME}}
| Image      = Dysplastic_nevus_-_intermed_mag.jpg
| Width      =
| Caption    = Dysplastic nevus. [[H&E stain]].
| Micro      = "bridges" between the sides of the rete ridges, draping fibrous tissue/fibrous tissue wraps around the rete ridges ("lamellar fibrosis"), nuclear atypia - see ''grading'' section, +/-junctional component (cells in the epidermis at the DE junction) larger than the intradermal component - ''shoulder phenomenon''
| Subtypes  = junctional, compound
| LMDDx      = [[melanoma in situ]], [[malignant melanoma]], [[compound melanocytic nevus]], [[atypical lentiginous nevus]]
| Stains    = [[Fontana-Masson stain]] +ve
| IHC        = S-100 +ve, HMB-45 +ve, MART-1 +ve, MITF +ve
| EM        =
| Molecular  =
| IF        =
| Gross      = "ugly duckling sign" - lesion looks different than the rest, [[Malignant_melanoma#Gross|ABCD criteria of melanoma]], usually greater than 5 mm
| Grossing  =
| Site      = [[skin]] - see [[melanocytic lesions]]
| Assdx      =
| Syndromes  = dysplastic nevus syndrome
| Clinicalhx =
| Signs      = ABCDEs of melanoma (asymmetry, border, colour, diameter, evolution)
| Symptoms  =
| Prevalence = common
| Bloodwork  =
| Rads      =
| Endoscopy  =
| Prognosis  = benign, increased risk of melanoma
| Other      =
| ClinDDx    = [[melanoma in situ]], other pigmented lesions
}}
'''Dysplastic nevus''', abbreviated '''DN''', is a common [[melanocytic lesion]] that is closely associated with [[malignant melanoma]].
 
It is also known as '''atypical nevus''', '''dysplastic melanocytic nevus''', '''Clark nevus''', and '''nevus with architectural disorder'''.
 
In 1992, the term ''nevus with architectural disorder'' was recommended by the American National Institutes of Health (NIH);<ref name=pmid1515516>{{Cite journal  | title = Diagnosis and treatment of early melanoma. NIH Consensus Development Conference. January 27-29, 1992. | journal = Consens Statement | volume = 10 | issue = 1 | pages = 1-25 | month =  | year =  | doi =  | PMID = 1515516 }}</ref> however, it is not widely adopted.<ref name=pmid22703907>{{Cite journal  | last1 = Elston | first1 = D. | title = Practical advice regarding problematic pigmented lesions. | journal = J Am Acad Dermatol | volume = 67 | issue = 1 | pages = 148-55 | month = Jul | year = 2012 | doi = 10.1016/j.jaad.2012.04.006 | PMID = 22703907 }}</ref> Also, based on a 2003 survey, it is the preferred term by only 15% of dermatologists.<ref name=pmid14568850>{{Cite journal  | last1 = Fung | first1 = MA. | title = Terminology and management of dysplastic nevi: responses from 145 dermatologists. | journal = Arch Dermatol | volume = 139 | issue = 10 | pages = 1374-5 | month = Oct | year = 2003 | doi = 10.1001/archderm.139.10.1374 | PMID = 14568850 }}</ref>
 
==General==
*Benign.
*Dysplastic nevi are considered a risk factor for [[malignant melanoma|melanoma]] and may be a precursor of melanoma, as the name ''dysplastic nevus'' suggests.<ref name=pmid21308311>{{Cite journal  | last1 = Rezze | first1 = GG. | last2 = Leon | first2 = A. | last3 = Duprat | first3 = J. | title = Dysplastic nevus (atypical nevus). | journal = An Bras Dermatol | volume = 85 | issue = 6 | pages = 863-71 | month = Dec | year = 2010 | doi =  | PMID = 21308311 }}</ref>
**Most melanoma cases do not have evidence of a pre-existing (dysplastic) nevus.<ref name=pmid21715047>{{Cite journal  | last1 = Longo | first1 = C. | last2 = Rito | first2 = C. | last3 = Beretti | first3 = F. | last4 = Cesinaro | first4 = AM. | last5 = Piñeiro-Maceira | first5 = J. | last6 = Seidenari | first6 = S. | last7 = Pellacani | first7 = G. | title = De novo melanoma and melanoma arising from pre-existing nevus: in vivo morphologic differences as evaluated by confocal microscopy. | journal = J Am Acad Dermatol | volume = 65 | issue = 3 | pages = 604-14 | month = Sep | year = 2011 | doi = 10.1016/j.jaad.2010.10.035 | PMID = 21715047 }}</ref>
*Large numbers of these nevi (10-100) are seen in ''dysplastic nevus syndrome''.<ref name=omim155600>{{OMIM|155600}}</ref>
**Individuals with this syndrome have an increased risk of melanoma and approximately one third of their melanomas arise from a ''dysplastic nevus''. The other two thirds arise ''de novo''.
 
Clinical:<ref name=pmid22220461>{{Cite journal  | last1 = Dediol | first1 = I. | last2 = Bulat | first2 = V. | last3 = Zivković | first3 = MV. | last4 = Marković | first4 = BM. | last5 = Situm | first5 = M. | title = Dysplastic nevus--risk factor or disguise for melanoma. | journal = Coll Antropol | volume = 35 Suppl 2 | issue =  | pages = 311-3 | month = Sep | year = 2011 | doi =  | PMID = 22220461 }}</ref>
*Associated with sun exposure.
 
Treatment:
*Dysplastic nevi with severe nuclear atypia are typically treated like [[melanoma in situ]] - complete excision with a 5 mm margin.<ref name=pmid15509670/>
*Dysplastic nevi with moderate nuclear atypia with margin involvement are re-excised.<ref name=pmid15509670>{{Cite journal  | last1 = Culpepper | first1 = KS. | last2 = Granter | first2 = SR. | last3 = McKee | first3 = PH. | title = My approach to atypical melanocytic lesions. | journal = J Clin Pathol | volume = 57 | issue = 11 | pages = 1121-31 | month = Nov | year = 2004 | doi = 10.1136/jcp.2003.008516 | PMID = 15509670 }}</ref>
 
==Gross==
Features:<ref name=pmid22220461/>
*"Ugly duckling sign" - lesion looks different than the rest.
*[[Malignant_melanoma#Gross|ABCD criteria of melanoma]].
*Tend to be greater than 5 mm - '''important'''.† <ref name=pmid3275948>{{Cite journal  | last1 = Barnhill | first1 = RL. | last2 = Hurwitz | first2 = S. | last3 = Duray | first3 = PH. | last4 = Arons | first4 = MS. | title = The dysplastic nevus: recognition and management. | journal = Plast Reconstr Surg | volume = 81 | issue = 2 | pages = 280-9 | month = Feb | year = 1988 | doi =  | PMID = 3275948 }}</ref>
 
Note:
* † Size matters - things smaller than 4 mm are usually ''not'' a dysplastic nevus.
 
==Microscopic==
Features:<ref name=Ref_WMSP502>{{Ref WMSP|502}}</ref>
*Melanocytes "bridges" between sides of rete ridges.
**Joining of three or more adjacent rete ridges = suspicious for melanoma.<ref name=pmid15509670/>
*Draping fibrous tissue - "lamellar fibrosis" - collagen deep to epidermis.
*Nuclear atypia - often moderate (small nucleoli visible with 20x objective) - see ''grading'' section.
*+/-Junctional component (cells in the epidermis at the DE junction) larger than the intradermal component - ''shoulder phenomenon''.
 
DDx:
*[[Melanoma in situ]] - especially on [[solar elastosis|sun damaged skin]] ([[lentigo maligna]]).<ref name=pmid15953373>{{Cite journal  | last1 = Farrahi | first1 = F. | last2 = Egbert | first2 = BM. | last3 = Swetter | first3 = SM. | title = Histologic similarities between lentigo maligna and dysplastic nevus: importance of clinicopathologic distinction. | journal = J Cutan Pathol | volume = 32 | issue = 6 | pages = 405-12 | month = Jul | year = 2005 | doi = 10.1111/j.0303-6987.2005.00355.x | PMID = 15953373 }}</ref><ref name=pmid10911797>{{Cite journal  | last1 = Edwards | first1 = SL. | last2 = Blessing | first2 = K. | title = Problematic pigmented lesions: approach to diagnosis. | journal = J Clin Pathol | volume = 53 | issue = 6 | pages = 409-18 | month = Jun | year = 2000 | doi =  | PMID = 10911797 }}</ref>
*[[Malignant melanoma]] - especially on sun damaged skin ([[lentigo maligna melanoma]]).
*[[Compound melanocytic nevus]].
*[[Atypical lentiginous nevus]].
 
===Images===
<gallery>
Image:Dysplastic_nevus_-_low_mag.jpg | Dysplastic nevus - low mag. (WC/Nephron)
Image:Dysplastic_nevus_-_intermed_mag.jpg | Dysplastic nevus - intermed. mag. (WC/Nephron)
Image:Dysplastic_nevus_-_add_-_high_mag.jpg | Dysplastic nevus - high mag. - shows bridging and lamellar fibrosis. (WC/Nephron)
Image:Dysplastic_nevus_-_add_-_very_high_mag.jpg | Dysplastic nevus - very high mag. - shows bridging and lamellar fibrosis. (WC/Nephron)
</gallery>
 
===Grading===
These lesions are often graded § :<ref name=Ref_Derm447-8>{{Ref Derm|447-8}}</ref>
{| class="wikitable sortable"
! Grade
! Size of nucleus
! Other features
|-
| Mild
| 1x keratinocyte nucleus
| no [[nucleoli]]/very small nucleoli †,<ref name=pmid12920220>{{Cite journal  | last1 = Arumi-Uria | first1 = M. | last2 = McNutt | first2 = NS. | last3 = Finnerty | first3 = B. | title = Grading of atypia in nevi: correlation with melanoma risk. | journal = Mod Pathol | volume = 16 | issue = 8 | pages = 764-71 | month = Aug | year = 2003 | doi = 10.1097/01.MP.0000082394.91761.E5 | PMID = 12920220 | URL = http://www.nature.com/modpathol/journal/v16/n8/full/3880837a.html }}</ref> slight hyperchromasia
|-
| Moderate
| 1-2x keratinocyte nucleus
| small nucleoli †, irregular nuclear contours
|-
| Severe
| >2x keratinocyte nucleus
| prominent nucleoli †‡
|}
† The sizes "very small", "small" and "prominent" are not defined; it is suggested that "very small" is visible with the 40x objective, "small" with the 20x objective and "prominent" with the 10x objective.  Focal, rare small nucleoli are not significant; they can be seen in benign melanocytic nevi.<br>
‡ Prominent nucleoli (alone) is considered enough to call "severe".<ref name=Ref_Derm447-8>{{Ref Derm|447-8}}</ref>
 
Notes:
*§ There is no consensus on this and practise (embarrassingly) is all over the map.<ref name=pmid22703907>{{Cite journal  | last1 = Elston | first1 = D. | title = Practical advice regarding problematic pigmented lesions. | journal = J Am Acad Dermatol | volume = 67 | issue = 1 | pages = 148-55 | month = Jul | year = 2012 | doi = 10.1016/j.jaad.2012.04.006 | PMID = 22703907 }}</ref>
**A two-tier grading system also exists (''low-grade'' (leave it alone) / ''high-grade'' (cut it out)).
**Some pathologists do not grade dysplastic nevi.
*Normal melanocytes have a nucleus that is ~70% the size of a resting basal keratocyte nucleus.
 
==Sign out==
===Compound===
<pre>
SKIN LESION, BACK, EXCISION:
- DYSPLASTIC COMPOUND NEVUS WITH MILD CYTOLOGIC ATYPIA AND MILD ARCHITECTURAL ATYPIA,
  COMPLETELY EXCISED IN THE PLANE OF SECTION (2 MM CLEARANCE).
</pre>
 
<pre>
SKIN LESION, CENTRAL BACK, EXCISION:
- DYSPLASTIC COMPOUND NEVUS WITH MILD CYTOLOGIC ATYPIA.
- NEAREST MARGIN (LATERAL MARGIN) 6 MM.
</pre>
====Micro====
The sections show hair-bearing skin with a compound melanocytic lesion.  The epidermal component extends at least three rete ridges further than the dermal component (shoulder phenomenon). There is bridging between the sides of the rete ridges and lamellar fibrosis.  The melanocyte nuclei are approximately the size of the keratinocyte nuclei, and do not have a prominent nucleolus (mild cytologic atypia).
 
There is no upward scatter of melanocytes and melanocytes in the dermis are mature.  No mitotic activity is appreciated.
 
===Junctional===
<pre>
SKIN LESION, LOWER BACK, EXCISION:
- DYSPLASTIC JUNCTIONAL MELANOCYTIC NEVUS WITH MILD NUCLEAR ATYPIA.
- NEAREST MARGIN (LATERAL MARGIN) 1 MM.
</pre>
 
A comment for lesions with mild cytologic atypia:
<pre>
COMMENT:
Excision of any clinically apparent residual components of the lesion
is suggested.
</pre>
 
====Micro====
The sections show hair-bearing skin with a junctional melanocytic lesion.  There is bridging between the sides of the rete ridges and lamellar fibrosis.  The melanocyte nuclei are approximately the size of the keratinocyte nuclei, and do not have a prominent
nucleolus (mild nuclear atypia).
 
There is no upward scatter of melanocytes.  No mitotic activity is appreciated.
 
==See also==
*[[Melanocytic lesions]].
*[[Atypical lentiginous nevus]].
 
==References==
{{Reflist|2}}
 
[[Category:Diagnosis]]
[[Category:Melanocytic lesions]]
Michael
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