Difference between revisions of "Melanocytic lesions"

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DDx:
DDx:
*[[Malignant melanoma]].
*[[Malignant melanoma]].
*[[Pigmented epithelioid melanocytoma]] - has nuclear atypia.
*[[Pigmented epithelioid melanocytoma]] - superificial dermis, has nuclear atypia.


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Revision as of 20:39, 7 November 2012

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

Identifying melanocytes

  • Clear or pigmented cytoplasm.
  • +/-Nuclear pseudoinclusions.
  • Epithelioid (superficial) or spindled (deep).

Benign lesions

Name Key feature Microscopic Clinical Gross Image Ref.
Lentigo simplex no nests, epidermis only slender rete with melanocytes; no nests of melanocytes; no dermal melanocytes < 40 years small flat pigmented lesion [1]
Junctional melanocytic nevus nests in epidermis nests of melanocytes at tips of rete, no dermal melanocytes usu. sun exposed skin, unusual in >50 years small flat (uniformly) pigmented lesion [1]
Compound melanocytic nevus benign nests in dermis & epidermis nests of melanocytes at tips of rete and in dermis; dermal melanocytes lack nucleoli, lack mitoses and "mature with depth" -- see Note 1. small slightly raised (uniformily) pigmented lesion [2]
Intradermal melanocytic nevus nested & individual melanocytes - only in dermis nested & individual melanocytes - only in dermis, +/- multinucleation, +/-pseudovascular spaces Clinical DDx: fibroepithelial polyp (skin tag), basal cell carcinoma raised, non-pigmented lesion [2]
Spitz nevus (epithelioid and spindle-cell nevus) long axis of nests perpendicular to surface, DE junction lesion spindled, epithelioid or mixed melanocytes, long axis of nests perpendicular to surface, superficial mitoses common, +/-hyperkeratosis, +/-acanthosis, +/-hypergranulosis Children & adolescents usu. non-pigmented Spitz nevus (drmihm.com), Spitz nevus - high mag. (WC), Spitz nevus - intermed. mag. (WC) [2]
Pigmented spindle cell nevus of Reed (AKA Pigmented spindle cell nevus) nests of heavily pigmented spindle cells, DE junction lesion heavily pigmented spindle cells in epidermis & dermis, form "basket weave" pattern, well-circumscribed women in teens & 20s; location: shoulder, pelvic girdle region Pigmented +++, small size Reed nevus - low mag. (WC), Reed nevus - intermed. mag. (WC), Reed nevus - collection (histopathology-india.net) [3]
Blue nevus lentil-shaped (ovoid) nests btw collagen bundles, dermal lesion lentil-shaped nests, mix of spindle or dendritic or epithelioid cell morphology, nests btw collagen usu. head & neck or extremities; clinically confused with melanoma[4] blue flat or slightly raised lesion Blue nevus (WC), Blue nevus - very low mag. (WC), Blue nevus - intermed. mag. (WC) [5]
Cellular blue nevus dermal lesion with pigmented spindle cells & epithelioid cells deep dermis +/-subcutis extension; cells lack nucleoli; biphasic: (1) epithelioid cells with pale cytoplasm, (2) pigmented spindle cells +/- melanophages congenital or acquired; usu. scalp or butt blue flat or raised lesion [5]
Congenital-pattern nevus growth along dermal structures extend along dermal structures (e.g. nerves, hair shafts, ducts); lacks atypia; +/-mitoses congenital or acquired; large ones increased melanoma risk[6] small, intermediate (2-20 cm) or large [5]
Dysplastic nevus (Clark's nevus) melanocyte bridges, lamellar fibrosis melanocytes "bridges" between sides of rete ridges, "lamellar fibrosis" (collagen deep to epidermis), mod. atypia may be familial - precursor to melanoma may have asymmetry in shape or pigmentation Dysplastic nevus - low mag., Dysplastic nevus - high mag. [7]
Halo nevus lymphocytes +++ lymphocytes at perimeter of melanocytic; epidermal melanocytes not nested; may be dermal, epidermal or both central zone of pigment [7]

Note 1:

  • "Maturation" in the context of melanocytic lesions means (1) the cells get smaller with depth, (2) cells are less mitotic with depth.

Lentigo simplex

General

  • Benign.
  • Usu. <40 years old.

Fits into the larger category of lentiginous melanocytic proliferations - these include:[8]

Gross

  • Small flat pigmented lesion.[1]

Microscopic

Features:[1]

  • Melanocytes in epidermis only.
  • No melanocytic nests.

Images:

Common melanocytic nevus

  • AKA common nevus.

General

  • Benign.
  • Common.
  • In common language: mole.
  • Think melanoma.

Clinical:

  • ABCD = asymmetric, borders (irregular), colour (black), diameter (large).

Microscopic

Features:

  • Symmetrical lesion.
  • "Matures" with depth
    • Less cellular with depth
    • Less nuclear atypia with depth.
    • Smaller cells with depth.
    • Smaller nests with depth.
  • Rare mitoses (superficial).
    • No deep mitoses.
  • No destruction of surrounding structures.
  • No nucleoli.

Subtypes

Compound melanocytic nevus
  • In the dermis and epidermis - key feature.
Junctional melanocytic nevus
  • In the epidermis - key feature.
Intradermal melanocytic nevus
  • AKA dermal nevus.
  • AKA intradermal melanocytic nevus.
  • AKA intradermal nevus, abbreviated IDN.[9]
  • Only in the dermis - key feature.

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Compound melanocytic nevus

SKIN LESION, RIGHT NECK, SHAVE BIOPSY:
- COMPOUND MELANOCYTIC NEVUS.
Micro

The sections show melanocytes in the dermis and epidermis. The lesion is symmetrical in its architecture and pigment distribution. There is no pagetoid spread of melanocytes in the epidermis. Superficially, melanocytes are in nests. Melanocytes mature with depth. No mitotic activity is appreciated.

The lesion is completely excised in the plane of section.

Intradermal melanocytic nevus

SKIN LESION, BACK, PUNCH BIOPSY: 
- INTRADERMAL MELANOCYTIC NEVUS.
Micro

The sections show melanocytes in the dermis separated from the epidermis by a Grenz zone. The lesion is symmetrical in its architecture and pigment distribution. Superficially, melanocytes are in nests. Melanocytes mature with depth. No mitotic activity is appreciated.

The lesion is completely excised in the plane of section.

Congenital-pattern nevus

  • AKA congenital nevus.

General

  • Congenital or acquired - thus "congenital-pattern".
  • Large ones increase melanoma risk.[6]
    • Small (<2 cm), intermediate (2-20 cm), large (>20 cm).

Microscopic

Features:[5]

  • Growth along dermal structures - key feature.
    • Nerves, hair shafts, ducts.
  • Lacks nuclear atypia.
  • +/-Mitoses.

Recurrent melanocytic nevus

  • AKA persistent melanocytic nevus.
  • AKA pseudomelanoma.

General

  • Classically, arises at the site of a partially excised nevus.[10]

Microscopic

Features - three layers (often described as a "sandwich"):

  1. Features of a compound nevus or junctional nevus.
  2. Scar.
    • Thick collagen bundles arranged parallel to the skin surface.
  3. Features of an intradermal nevus.

May have:[10]

  • Pagetoid spread of melanocytes.
  • Confluent nests at the DE junction.
  • Nuclear atypia - uncommon.

DDx:[10]

  • Melanoma in situ - classically spread beyond the scar, unlike pseudomelanoma - growth confined to epidermis.

IHC

  • HMB-45 deep component -ve.
  • Ki-67 - non-proliferative.

Sclerosing melanocytic nevus

  • AKA sclerosing nevus.

General

Microscopic

Features:[11]

  • Trizonal - may be described as a sandwich:
    1. Junctional or compound nevus.
      • May have pagetoid spread of melanocytes, i.e. non-basal melanocytes in the epidermis.
      • Cannot have cytologic atypia - presence of cytologic atypia in this layer makes it melanoma.
    2. Fibrotic tissue with irregular melanocytic nests.
    3. Nevus below scar - may be common, congenital-type, dysplastic, Spitz.

DDx:

Pigmented spindle cell nevus

  • AKA pigmented spindle cell nevus of Reed.

General

  • Uncommon.
  • Women in teens & 20s.
  • Location: shoulder, pelvic girdle region.

Microscopic

Features:[3]

  • Nests of heavily pigmented spindle cells at dermal-epidermal junction - key feature.
    • Nevoid cells in epidermis & dermis - form "basket weave" pattern
  • Well-circumscribed lesion.

Notes:

  • No epithelioid nevus cells.

DDx:

Images:

Spitz nevus

  • AKA epithelioid and spindle-cell nevus.

General

  • May be very difficult to differentiate from melanoma.

Epidemiology:

  • Children & adolescents.

Treatment:

  • Complete excision.[12]

Gross

  • Usually face or extremity.[13]

Microscopic

Features:[2]

  • Architecture:
    • Nests of cells (spindle, epithelioid or spindle/epithelioid) - in both dermis and epidermis.
      • Nests are vertically arranged, i.e. the long axis of the nests are perpendicular to the skin surface.
        • Nest arrangement/orientation described as "cluster of bananas".
  • +/-Hyperkeratosis (more keratin, i.e. thick stratum corneum).
  • +/-Hypergranulosis (thick stratum granulosum).
  • +/-Acanthosis (thick stratum spinosum).
  • Kamino bodies (also written Camino bodies) - dense eosinophilic bodies.[14]
    • Apoptotic cells.
    • Kamino bodies are rare in melanoma.

Notes:

DDx:

Images:

Blue nevus

Common blue nevus redirects here.
  • Abbreviated BN.

General

  • Usually head & neck, extremities (e.g. dorsum of wrist or foot) or buttock.[16]
  • Clinically confused with malignant melanoma.[4]

Clinical:

  • Blue flat or slightly raised lesion.

Microscopic

Features:[5]

  • Lentil-shaped (ovoid) nests between collagen bundles.
  • Mix of spindle or dendritic or epithelioid cell morphology.

Notes:[17]

  • Classically no epidermal component.
    • The entity compound blue nevus has been described; it is rare.[18]
  • May be assoc. with a hair follicle.

DDx:

Images:

Variants of blue nevus

Several histologic variants:[17]

  • 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 = Common, Cellular, Amelanotic, Sclerosing, Epithelioid.

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SKIN LESION, RIGHT WRIST DORSUM, PUNCH BIOPSY: 
	- COMMON BLUE NEVUS.

SKIN LESION, LEFT SHIN, PUNCH BIOPSY: 
	- SCLEROSING BLUE NEVUS.

Cellular blue nevus

General

Microscopic

Features:[5]

  • Dermal lesion with pigmented spindle cells & epithelioid cells - key feature.
  • Cells lack nucleoli.
  • Biphasic:
    1. Epithelioid cells with pale cytoplasm.
    2. Pigmented spindle cells +/- melanophages.

Images:

Acral nevus

  • AKA melanocytic nevus with intraepidermal ascent of cells (MANIAC).

General

  • Palms or soles.

Microscopic

Features:

  • Nevus with intraepidermal ascent of cells.

Notes:

  • Intraepidermal ascent of cells is usually suggestive of melanoma.
    • In acral sites the criteria are relaxed, i.e. this is considered benign for this site.

Dysplastic melanocytic nevus

  • AKA dysplastic nevus.
  • AKA Clark nevus.

General

  • Benign.
  • Dysplastic nevi are considered a risk factor for melanoma and may be a precursor of melanoma, as the name dysplastic nevus suggests.[19]
    • Most melanoma cases do not have evidence of a pre-existing (dysplastic) nevus.[20]
  • Large numbers of these nevi (10-100) are seen in dysplastic nevus syndrome.[21]
    • Individuals with this syndrome have an increased risk of melanoma and approximately one third of their melanomas arise from a Clark nevus. The other two thirds arise de novo.

Clinical:[22]

  • Associated with sun exposure.

Treatment:

  • Dysplastic nevi with severe nuclear atypia are treated like melanoma - excision with a 5 mm margin.
  • Dysplastic nevi with moderate nuclear atypia with margin involvement are re-excised.[23]

Gross

Features:[22]

  • "Ugly duckling sign" - lesion looks different than the rest.
  • ABCDE criteria of in melanoma.

Microscopic

Features:[7]

  • Melanocytes "bridges" between sides of rete ridges.
    • Joining of three or more adjacent rete ridges = suspicious for melanoma.[23]
  • Drapping fibrous tissue - "lamellar fibrosis" - collagen deep to epidermis.
  • Usually moderate nuclear atypia (small nucleoli present) - see grading section.
  • Junctional component (cells in the epidermis at the DE junction) larger than the intradermal component - shoulder phenomenon.

DDx:

Images:

Grading

These lesions are usually graded:[24]

Grade Size of nucleus Other features
Mild 1x keratinocyte nucleus no nucleoli/very small nucleoli †,[25] 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.
‡ Prominent nucleoli (alone) is considered enough to call "severe".[24]

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Compound

SKIN, CENTRAL BACK, EXCISION:
- DYSPLASTIC MELANOCYTIC NEVUS WITH MILD NUCLEAR ATYPIA.
- NEAREST MARGIN (LATERAL MARGIN) 6 MM.


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 nuclear atypia).

There is no upward scatter of melanocytes and melanocytes in the dermis are mature. No mitotic activity is appreciated.

Junctional

SKIN, LOWER BACK, EXCISION:
- DYSPLASTIC JUNCTIONAL MELANOCYTIC NEVUS WITH MILD NUCLEAR ATYPIA.
- NEAREST MARGIN (LATERAL MARGIN) 1 MM.
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.

Neurocristic hamartoma

Main article: Neurocristic hamartoma

Desmoplastic melanocytic nevus

  • AKA sclerosing melanocytic nevus.

General

  • Benign.

Gross

  • Usu. "small" and symmetric.

Clinical DDx:

Microscopic

Features:[26]

DDx:

IHC

Features:[26]

  • Melan A (MART-1) +ve (not usu. +ve in desmoplastic melanoma).[26]
  • S-100 +ve.
  • Ki-67 -- only rare cells.

Solar lentigo

  • Plural solar lentigines.

General

  • Benign.

Fits into the larger category of lentiginous melanocytic proliferations - these include:[8]

Gross

Features:[8]

  • Small (< 4 mm), irregular brown macule.
  • Usu. sun-exposed area.

DDx (clinical):

Microscopic

Features:[27]

  • Hyperpigmented melanocytes - may be present in increased quantities - key feature.
    • Classically at the tips of the rete ridges.
  • No (melanocyte) nuclear atypia.

Notes:

  • Should not be present:[8]
    • Nests of melanocytes.
    • Pagetoid spread of melanocytes.

DDx:[27]

Image:

Combined melanocytic nevus

  • AKA combined nevus.

General

  • Uncommon.
  • Morphologic features of two types of melanocytic nevi.

Microscopic

Features:[28]

  • Morphologic features of two types of melanocytic nevi.

DDx:

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A. SKIN LESION, LEFT UPPER ARM, PUNCH BIOPSY:
- COMBINED MELANOCYTIC NEVUS (INTRADERMAL MELANOCYTIC NEVUS AND BLUE NEVUS).

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 498. ISBN 978-0781765275.
  2. ↑ 2.0 2.1 2.2 2.3 Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 499. ISBN 978-0781765275.
  3. ↑ 3.0 3.1 Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 500. ISBN 978-0781765275.
  4. ↑ 4.0 4.1 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. 592. ISBN 978-1416054542.
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 501. ISBN 978-0781765275.
  6. ↑ 6.0 6.1 Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson; Aster, Jon (2009). Robbins and Cotran pathologic basis of disease (8th ed.). Elsevier Saunders. pp. 1170. ISBN 978-1416031215.
  7. ↑ 7.0 7.1 7.2 Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 502. ISBN 978-0781765275.
  8. ↑ 8.0 8.1 8.2 8.3 Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 438. ISBN 978-0443066542.
  9. ↑ Fullen, DR.; Reed, JA.; Finnerty, B.; McNutt, NS. (Sep 2001). "S100A6 preferentially labels type C nevus cells and nevic corpuscles: additional support for Schwannian differentiation of intradermal nevi.". J Cutan Pathol 28 (8): 393-9. PMID 11493376.
  10. ↑ 10.0 10.1 10.2 Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 465. ISBN 978-0443066542.
  11. ↑ 11.0 11.1 Fabrizi, G.; Pennacchia, I.; Pagliarello, C.; Massi, G. (Nov 2008). "Sclerosing nevus with pseudomelanomatous features.". J Cutan Pathol 35 (11): 995-1002. doi:10.1111/j.1600-0560.2007.00941.x. PMID 18537860.
  12. ↑ Gelbard, SN.; Tripp, JM.; Marghoob, AA.; Kopf, AW.; Koenig, KL.; Kim, JY.; Bart, RS. (Aug 2002). "Management of Spitz nevi: a survey of dermatologists in the United States.". J Am Acad Dermatol 47 (2): 224-30. PMID 12140468.
  13. ↑ Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 449. ISBN 978-0443066542.
  14. ↑ Kirkwood, John M.; Jukic, Drazen; Averbook, Bruce J.; Sender, Leonard S. (October 2009). "Melanoma in Pediatric, Adolescent, and Young Adult Patients". Semin Oncol. 36 (5): 419-31. PMC 2797485. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2797485/.
  15. ↑ Jakubovic, H. 16 July 2010.
  16. ↑ Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 456. ISBN 978-0443066542.
  17. ↑ 17.0 17.1 Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 457. ISBN 978-0443066542.
  18. ↑ Kamino, H.; Tam, ST. (Oct 1990). "Compound blue nevus: a variant of blue nevus with an additional junctional dendritic component. A clinical, histopathologic, and immunohistochemical study of six cases.". Arch Dermatol 126 (10): 1330-3. PMID 2221938.
  19. ↑ Rezze, GG.; Leon, A.; Duprat, J. (Dec 2010). "Dysplastic nevus (atypical nevus).". An Bras Dermatol 85 (6): 863-71. PMID 21308311.
  20. ↑ Longo, C.; Rito, C.; Beretti, F.; Cesinaro, AM.; Piñeiro-Maceira, J.; Seidenari, S.; Pellacani, G. (Sep 2011). "De novo melanoma and melanoma arising from pre-existing nevus: in vivo morphologic differences as evaluated by confocal microscopy.". J Am Acad Dermatol 65 (3): 604-14. doi:10.1016/j.jaad.2010.10.035. PMID 21715047.
  21. ↑ Online 'Mendelian Inheritance in Man' (OMIM) 155600
  22. ↑ 22.0 22.1 Dediol, I.; Bulat, V.; Zivković, MV.; Marković, BM.; Situm, M. (Sep 2011). "Dysplastic nevus--risk factor or disguise for melanoma.". Coll Antropol 35 Suppl 2: 311-3. PMID 22220461.
  23. ↑ 23.0 23.1 Culpepper, KS.; Granter, SR.; McKee, PH. (Nov 2004). "My approach to atypical melanocytic lesions.". J Clin Pathol 57 (11): 1121-31. doi:10.1136/jcp.2003.008516. PMID 15509670.
  24. ↑ 24.0 24.1 Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 447-8. ISBN 978-0443066542.
  25. ↑ Arumi-Uria, M.; McNutt, NS.; Finnerty, B. (Aug 2003). "Grading of atypia in nevi: correlation with melanoma risk.". Mod Pathol 16 (8): 764-71. doi:10.1097/01.MP.0000082394.91761.E5. PMID 12920220.
  26. ↑ 26.0 26.1 26.2 Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 464. ISBN 978-0443066542.
  27. ↑ 27.0 27.1 Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 437. ISBN 978-0443066542.
  28. ↑ 28.0 28.1 Baran, JL.; Duncan, LM. (Oct 2011). "Combined melanocytic nevi: histologic variants and melanoma mimics.". Am J Surg Pathol 35 (10): 1540-8. doi:10.1097/PAS.0b013e31822e9f5e. PMID 21881487.
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