Difference between revisions of "Melanocytic lesions"

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===Microscopic===
===Microscopic===
Features:<ref>need ref</ref>
Features:
*Symmetrical lesion.
*Symmetrical lesion.
*"Matures" with depth - less cellular, less atypia.
*"Matures" with depth  
*No destruction of surrounding structures.
**Less cellular with depth
**Less nuclear atypia with depth.
**Smaller cells with depth.
*Only in dermis '''key feature'''.
*Only in dermis '''key feature'''.
**Otherwise it is something else, e.g. ''dermal nevus'', ''junctional nevus''.
**Otherwise it is something else, e.g. ''dermal nevus'', ''junctional nevus''.
 
*Rare mitoses (superficial).
===Microscopic===
**No deep mitoses.
*Basaloid cells mixed with squamous cells.  
*No destruction of surrounding structures.
*Keratin-filled invaginations.  
*No nucleoli.
*Horn cysts - intraepidermal, brown globule-like structures.  
**Melanocytes at the dermoepidermal junction.<ref>URL: [http://emedicine.medscape.com/article/1059477-overview http://emedicine.medscape.com/article/1059477-overview].</ref>


==Spitz nevus==
==Spitz nevus==

Revision as of 00:41, 17 October 2011

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

  • Pigmented.
  • Clear cytoplasm.

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) [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" btw sides of rete, "lamellar fibrosis" (collagen deep to epidermis), mod. atypia may be familial - precursor to melanoma may have asymmetry in shape or pigmentation [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.

Dermal nevus

General

  • 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.
  • Only in dermis key feature.
    • Otherwise it is something else, e.g. dermal nevus, junctional nevus.
  • Rare mitoses (superficial).
    • No deep mitoses.
  • No destruction of surrounding structures.
  • No nucleoli.

Spitz nevus

  • AKA epithelioid and spindle-cell nevus.

Epidemiology

  • Children & adolescents.

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).
  • NEVER in the setting of solar elastosis.[8]
    • If there is solar elastosis -- it's melanoma.
  • Camino bodies (also written Kamino bodies) - dense eosinophilic bodies at dermoepidermal junction.[9]

Images:

Blue nevus

General

  • Usu. head & neck or extremities; clinically confused with 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.

Images:

Cellular blue nevus

General

  • Congenital or acquired.
  • Usu. scalp or butt.

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:

See also

References

  1. ↑ 1.0 1.1 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. ↑ 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 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. ↑ 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 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. ↑ HJ. 16 July 2010.
  9. ↑ URL: http://www.pathologyoutlines.com/topic/skintumorspitz.html. Accessed on: 18 May 2011.
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