Difference between revisions of "Melanocytic lesions"

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Melanocytic lesions (view source)

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'''Melanocytic lesions''' are commonly encountered in [[dermatopathology]] and an area which causes some difficulty, i.e. it is hard to decide in some cases whether a lesion is benign (e.g. [[Spitz nevus]]) or malignant ([[malignant melanoma]]).
'''Melanocytic lesions''' are commonly encountered in [[dermatopathology]] and an area which causes some difficulty, i.e. it is hard to decide in some cases whether a lesion is benign (e.g. [[Spitz nevus]]) or malignant ([[malignant melanoma]]).


==Overview==
=Overview=
===Identifying melanocytes===
===Identifying melanocytes===
*Clear ''or'' pigmented cytoplasm.
*Clear ''or'' pigmented cytoplasm.
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*"Maturation" in the context of melanocytic lesions ''means'' (1) the cells get smaller with depth, (2) cells are less mitotic with depth.
*"Maturation" in the context of melanocytic lesions ''means'' (1) the cells get smaller with depth, (2) cells are less mitotic with depth.


=Lentiginous lesions=
==Lentigo simplex==
==Lentigo simplex==
*[[AKA]] ''simple lentigo''.<ref>URL: [http://www.dermnetnz.org/lesions/lentigo-simplex.html http://www.dermnetnz.org/lesions/lentigo-simplex.html]. Accessed on: 27 March 2013.</ref>
*[[AKA]] ''simple lentigo''.<ref>URL: [http://www.dermnetnz.org/lesions/lentigo-simplex.html http://www.dermnetnz.org/lesions/lentigo-simplex.html]. Accessed on: 27 March 2013.</ref>
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- BENIGN SIMPLE LENTIGO.
- BENIGN SIMPLE LENTIGO.
</pre>
</pre>
==Solar lentigo==
*Plural ''solar lentigines''.
===General===
*Benign.
Fits into the larger category of ''lentiginous melanocytic proliferations'' - these include:<ref name=Ref_Derm438>{{Ref Derm|438}}</ref>
*Solar lentigo.
*[[Lentigo simplex]].
*Lentiginous nevus.
*Lentiginous [[melanoma in situ]].
===Gross===
Features:<ref name=Ref_Derm438>{{Ref Derm|438}}</ref>
*Small (< 4 mm), irregular brown [[macule]].
*Usu. sun-exposed area.
DDx (clinical):
*[[Lentigo maligna]] - melanoma in situ on sun damaged skin.
*[[Seborrheic keratosis]], flat.<ref name=dermammin_sl>URL: [http://www.dermaamin.com/site/histopathology-of-the-skin/53-a/1555-actinic-lentigo-.html http://www.dermaamin.com/site/histopathology-of-the-skin/53-a/1555-actinic-lentigo-.html]. Accessed on: 6 May 2013.</ref>
===Microscopic===
Features:<ref name=Ref_Derm437>{{Ref Derm|437}}</ref>
*Hyperpigmented melanocytes - may be present in increased quantities - '''key feature'''.
**Classically at the tips of the rete ridges.
*No (melanocyte) nuclear atypia.
*Solar damage ([[solar elastosis]]).<ref name=pmid19536147/>
Notes:
*Should ''not'' be present:<ref name=Ref_Derm438>{{Ref Derm|438}}</ref>
**Nests of melanocytes.
**Pagetoid spread of melanocytes.
DDx:<ref name=Ref_Derm437>{{Ref Derm|437}}</ref>
*Pigmented [[actinic keratosis]].
*[[Lichen planus-like keratosis]].
*Pigmented [[seborrheic keratosis]].
Images:
*[http://commons.wikimedia.org/wiki/File:Skin_tumors_181.jpg Solar lentigo (WC)].
*[http://www.dermaamin.com/site/images/histo-pic/a/actinic-lentigo/actinic-lentigo1.jpg Solar lentigo (dermammin.com)].<ref name=dermammin_sl>URL: [http://www.dermaamin.com/site/histopathology-of-the-skin/53-a/1555-actinic-lentigo-.html http://www.dermaamin.com/site/histopathology-of-the-skin/53-a/1555-actinic-lentigo-.html]. Accessed on: 6 May 2013.</ref>
===Sign out===
<pre>
FOREARM LESION, RIGHT, PUNCH BIOPSY:
- SOLAR LENTIGO.
</pre>
====Micro====
The sections show hair-bearing skin with basilar pigmentation at the tips of the rete ridges and solar elastosis.  No melanocytic nests are identified.  The epidermal cells mature to the surface.  No significant inflammation is present.


==Lentiginous melanocytic nevus==
==Lentiginous melanocytic nevus==
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*[http://commons.wikimedia.org/wiki/File:Skin_Tumors-171.jpg Lentiginous nevus (WC)].
*[http://commons.wikimedia.org/wiki/File:Skin_Tumors-171.jpg Lentiginous nevus (WC)].


=Nested melanocytic lesions=
==Common melanocytic nevus==
==Common melanocytic nevus==
*[[AKA]] ''common nevus''.
*[[AKA]] ''common nevus''.
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*[[WC]]:
*[[WC]]:
**[http://commons.wikimedia.org/wiki/File:Spitz_nevus_-_intermed_mag.jpg Spitz nevus - intermed. mag. (WC)].
**[http://commons.wikimedia.org/wiki/File:Spitz_nevus_-_intermed_mag.jpg Spitz nevus - intermed. mag. (WC)].
==Blue nevus==
:'''''Common blue nevus''' redirects here''.
*Abbreviated ''BN''.
===General===
*Usually head & neck, extremities (e.g. dorsum of wrist or foot) or buttock.<ref name=Ref_Derm456>{{Ref Derm|456}}</ref>
*Clinically confused with [[malignant melanoma]].<ref name=Ref_PCPBoD8_592>{{Ref PCPBoD8|592}}</ref>
*Second most common melanocytic lesion of the oral cavity.<ref>URL: [http://emedicine.medscape.com/article/1079272-overview http://emedicine.medscape.com/article/1079272-overview]. Accessed on: 10 December 2012.</ref>
**Most common melanocytic lesion ''[[intramucosal melanocytic nevus]]''.
===Gross===
*Blue flat or slightly raised lesion.
===Microscopic===
Features:<ref name=Ref_WMSP501>{{Ref WMSP|501}}</ref>
*Lentil-shaped (ovoid) nests between collagen bundles.
*Mix of spindle or dendritic or epithelioid cell morphology.
Notes:<ref name=Ref_Derm457>{{Ref Derm|457}}</ref>
*Classically no epidermal component.
** The entity ''compound blue nevus'' has been described; it is rare.<ref name=pmid2221938>{{Cite journal  | last1 = Kamino | first1 = H. | last2 = Tam | first2 = ST. | title = Compound blue nevus: a variant of blue nevus with an additional junctional dendritic component. A clinical, histopathologic, and immunohistochemical study of six cases. | journal = Arch Dermatol | volume = 126 | issue = 10 | pages = 1330-3 | month = Oct | year = 1990 | doi =  | PMID = 2221938 }}
</ref>
*May be assoc. with a hair follicle.
DDx:
*[[Dermatofibroma]] - esp. amelanotic BN.
*[[Malignant melanoma]].
*[[Clear cell sarcoma]].
*[[Combined melanocytic nevus]] - blue nevus found together with another nevus (classically [[common melanocytic nevus]]), superficial.
*[[Pigmented epithelioid melanocytoma]] - superificial dermis, has nuclear atypia.
Images:
*[http://commons.wikimedia.org/wiki/File:Blue_nevus_%281_of_4%29.jpg Blue nevus (WC)].
*[http://commons.wikimedia.org/wiki/File:Blue_nevus_-_very_low_mag.jpg Blue nevus - very low mag. (WC)].
*[http://commons.wikimedia.org/wiki/File:Blue_nevus_-_intermed_mag.jpg Blue nevus - intermed. mag. (WC)].
====Variants of blue nevus====
Several histologic variants:<ref name=Ref_Derm457>{{Ref Derm|457}}</ref>
*Common blue nevus - the blue nevus not otherwise specified.
*[[Cellular blue nevus]].
*Amelanotic blue nevus - may be confused with a [[dermatofibroma]].
*Sclerosing blue nevus - has stromal fibrosis.
*Epithelioid blue nevus.
Memory device:
*''C CASE'' = '''C'''ommon, '''C'''ellular, '''A'''melanotic, '''S'''clerosing, '''E'''pithelioid.
===Sign out===
<pre>
SKIN LESION, RIGHT WRIST DORSUM, PUNCH BIOPSY:
- COMMON BLUE NEVUS.
</pre>
<pre>
SKIN LESION, LEFT SHIN, PUNCH BIOPSY:
- SCLEROSING BLUE NEVUS.
</pre>
====Micro====
The sections show pigmented spindle cells in the dermis between collagen bundles. The spindle cells show no nuclear atypia and no mitotic activity is appreciated.
The lesion does not extend into the epidermis. There are no melanocyte nests. There is no significant inflammation. The lesion is completely excised.
The pigmented cells are negative on the Prussian blue stain.
==Cellular blue nevus==
===General===
*Congenital or acquired.
*Usually scalp or butt.
*Variant of the ''[[common blue nevus]]''.
===Microscopic===
Features:<ref name=Ref_WMSP501>{{Ref WMSP|501}}</ref>
*Dermal lesion with pigmented spindle cells & epithelioid cells - '''key feature'''.
*Cells lack nucleoli.
*Biphasic:
*# Epithelioid cells with pale cytoplasm.
*# Pigmented spindle cells +/- melanophages.
Images:
*[http://www.dermpedia.org/case/cellular-blue-nevus-0 Cellular blue nevus (dermpedia.org)].


==Acral nevus==
==Acral nevus==
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There is no upward scatter of melanocytes.  No mitotic activity is appreciated.
There is no upward scatter of melanocytes.  No mitotic activity is appreciated.
==Neurocristic hamartoma==
{{Main|Neurocristic hamartoma}}


==Desmoplastic melanocytic nevus==
==Desmoplastic melanocytic nevus==
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*Ki-67 -- only rare cells.
*Ki-67 -- only rare cells.


==Solar lentigo==
=Miscellaneous=
*Plural ''solar lentigines''.
==Blue nevus==
:'''''Common blue nevus''' redirects here''.
*Abbreviated ''BN''.
===General===
===General===
*Benign.
*Usually head & neck, extremities (e.g. dorsum of wrist or foot) or buttock.<ref name=Ref_Derm456>{{Ref Derm|456}}</ref>
 
*Clinically confused with [[malignant melanoma]].<ref name=Ref_PCPBoD8_592>{{Ref PCPBoD8|592}}</ref>
Fits into the larger category of ''lentiginous melanocytic proliferations'' - these include:<ref name=Ref_Derm438>{{Ref Derm|438}}</ref>
*Second most common melanocytic lesion of the oral cavity.<ref>URL: [http://emedicine.medscape.com/article/1079272-overview http://emedicine.medscape.com/article/1079272-overview]. Accessed on: 10 December 2012.</ref>
*Solar lentigo.
**Most common melanocytic lesion ''[[intramucosal melanocytic nevus]]''.
*[[Lentigo simplex]].
*Lentiginous nevus.
*Lentiginous [[melanoma in situ]].


===Gross===
===Gross===
Features:<ref name=Ref_Derm438>{{Ref Derm|438}}</ref>
*Blue flat or slightly raised lesion.
*Small (< 4 mm), irregular brown [[macule]].
*Usu. sun-exposed area.
 
DDx (clinical):
*[[Lentigo maligna]] - melanoma in situ on sun damaged skin.
*[[Seborrheic keratosis]], flat.<ref name=dermammin_sl>URL: [http://www.dermaamin.com/site/histopathology-of-the-skin/53-a/1555-actinic-lentigo-.html http://www.dermaamin.com/site/histopathology-of-the-skin/53-a/1555-actinic-lentigo-.html]. Accessed on: 6 May 2013.</ref>


===Microscopic===
===Microscopic===
Features:<ref name=Ref_Derm437>{{Ref Derm|437}}</ref>
Features:<ref name=Ref_WMSP501>{{Ref WMSP|501}}</ref>
*Hyperpigmented melanocytes - may be present in increased quantities - '''key feature'''.
*Lentil-shaped (ovoid) nests between collagen bundles.
**Classically at the tips of the rete ridges.
*Mix of spindle or dendritic or epithelioid cell morphology.
*No (melanocyte) nuclear atypia.
*Solar damage ([[solar elastosis]]).<ref name=pmid19536147/>


Notes:
Notes:<ref name=Ref_Derm457>{{Ref Derm|457}}</ref>
*Should ''not'' be present:<ref name=Ref_Derm438>{{Ref Derm|438}}</ref>
*Classically no epidermal component.
**Nests of melanocytes.  
** The entity ''compound blue nevus'' has been described; it is rare.<ref name=pmid2221938>{{Cite journal  | last1 = Kamino | first1 = H. | last2 = Tam | first2 = ST. | title = Compound blue nevus: a variant of blue nevus with an additional junctional dendritic component. A clinical, histopathologic, and immunohistochemical study of six cases. | journal = Arch Dermatol | volume = 126 | issue = 10 | pages = 1330-3 | month = Oct | year = 1990 | doi =  | PMID = 2221938 }}
**Pagetoid spread of melanocytes.
</ref>
*May be assoc. with a hair follicle.


DDx:<ref name=Ref_Derm437>{{Ref Derm|437}}</ref>
DDx:
*Pigmented [[actinic keratosis]].
*[[Dermatofibroma]] - esp. amelanotic BN.
*[[Lichen planus-like keratosis]].
*[[Malignant melanoma]].
*Pigmented [[seborrheic keratosis]].
*[[Clear cell sarcoma]].
*[[Combined melanocytic nevus]] - blue nevus found together with another nevus (classically [[common melanocytic nevus]]), superficial.
*[[Pigmented epithelioid melanocytoma]] - superificial dermis, has nuclear atypia.  


Images:
Images:
*[http://commons.wikimedia.org/wiki/File:Skin_tumors_181.jpg Solar lentigo (WC)].
*[http://commons.wikimedia.org/wiki/File:Blue_nevus_%281_of_4%29.jpg Blue nevus (WC)].  
*[http://www.dermaamin.com/site/images/histo-pic/a/actinic-lentigo/actinic-lentigo1.jpg Solar lentigo (dermammin.com)].<ref name=dermammin_sl>URL: [http://www.dermaamin.com/site/histopathology-of-the-skin/53-a/1555-actinic-lentigo-.html http://www.dermaamin.com/site/histopathology-of-the-skin/53-a/1555-actinic-lentigo-.html]. Accessed on: 6 May 2013.</ref>
*[http://commons.wikimedia.org/wiki/File:Blue_nevus_-_very_low_mag.jpg Blue nevus - very low mag. (WC)].  
*[http://commons.wikimedia.org/wiki/File:Blue_nevus_-_intermed_mag.jpg Blue nevus - intermed. mag. (WC)].
 
====Variants of blue nevus====
Several histologic variants:<ref name=Ref_Derm457>{{Ref Derm|457}}</ref>
*Common blue nevus - the blue nevus not otherwise specified.
*[[Cellular blue nevus]].
*Amelanotic blue nevus - may be confused with a [[dermatofibroma]].
*Sclerosing blue nevus - has stromal fibrosis.
*Epithelioid blue nevus.
 
Memory device:  
*''C CASE'' = '''C'''ommon, '''C'''ellular, '''A'''melanotic, '''S'''clerosing, '''E'''pithelioid.


===Sign out===
===Sign out===
<pre>
<pre>
FOREARM LESION, RIGHT, PUNCH BIOPSY:
SKIN LESION, RIGHT WRIST DORSUM, PUNCH BIOPSY:  
- SOLAR LENTIGO.
- COMMON BLUE NEVUS.
</pre>
 
<pre>
SKIN LESION, LEFT SHIN, PUNCH BIOPSY:
- SCLEROSING BLUE NEVUS.
</pre>
</pre>


====Micro====
====Micro====
The sections show hair-bearing skin with basilar pigmentation at the tips of the rete ridges and solar elastosis. No melanocytic nests are identified. The epidermal cells mature to the surface. No significant inflammation is present.
The sections show pigmented spindle cells in the dermis between collagen bundles. The spindle cells show no nuclear atypia and no mitotic activity is appreciated.
 
The lesion does not extend into the epidermis. There are no melanocyte nests. There is no significant inflammation. The lesion is completely excised.
 
The pigmented cells are negative on the Prussian blue stain.
 
==Cellular blue nevus==
===General===
*Congenital or acquired.
*Usually scalp or butt.
*Variant of the ''[[common blue nevus]]''.
 
===Microscopic===
Features:<ref name=Ref_WMSP501>{{Ref WMSP|501}}</ref>
*Dermal lesion with pigmented spindle cells & epithelioid cells - '''key feature'''.
*Cells lack nucleoli.
*Biphasic:
*# Epithelioid cells with pale cytoplasm.
*# Pigmented spindle cells +/- melanophages.
 
Images:
*[http://www.dermpedia.org/case/cellular-blue-nevus-0 Cellular blue nevus (dermpedia.org)].


==Combined melanocytic nevus==
==Combined melanocytic nevus==
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</pre>
</pre>


==See also==
==Neurocristic hamartoma==
{{Main|Neurocristic hamartoma}}
 
=See also=
*[[Dermatopathology]].
*[[Dermatopathology]].
*[[Cytopathology]].
*[[Cytopathology]].
*[[Non-malignant skin disease]].
*[[Non-malignant skin disease]].


==References==
=References=
{{reflist|2}}
{{reflist|2}}


==External links==
=External links=
*[http://www.youtube.com/watch?v=_4jgUcxMezM Dear 16 year-old me (youtube.com)] - with Dr. G.
*[http://www.youtube.com/watch?v=_4jgUcxMezM Dear 16 year-old me (youtube.com)] - with Dr. G.


[[Category:Dermatopathology]]
[[Category:Dermatopathology]]
Michael
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