Dysplastic nevus

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Author: Mikael Häggström [notes 1]
A suspected dysplastic nevus (also called dysplastic melanocytic nevus) generally presents as a dark skin focality.

Gross processing of skin excisions

Gross pathologic processing of skin excisions[1][notes 2]
Lesion size
<4 mm 4 - 8 mm 9 - 15 mm
Benign appearance

Tissue selection from skin excision with lesion less than 4 mm with benign appearance.png

Tissue selection from skin excision with lesion 4-8 mm with benign appearance.png

Tissue selection from skin excision with lesion 9-15 mm with benign appearance.png

Suspected malignancy Tissue selection from skin excision with less than 4 mm suspected malignant lesion.png Tissue selection from skin excision with 4-8 mm suspected malignant lesion.png Tissue selection from skin excision with 9-15 mm suspected malignant lesion.png

In table above, each top image shows recommended lines for cutting out slices to be submitted for further processing. Bottom image shows which side of the slice that should be put to microtomy. Dashed lines here mean that either side could be used.

Further information: Gross processing of skin excisions

Microscopic evaluation

Mandatory findings:[2]

  • Shoulder phenomenon, meaning that the extent of the dermal component is larger than the epidermal component.
  • Lentiginous proliferation, meaning an increased amount of melanocytes in the basal area, along rete pegs and sometimes between them.
  • Irregularly distributed nests of melanocytes.
  • Atypia

Grading

It is acceptable to grade a dysplastic nevus into either low or high grade by the following algorithm:[3][notes 3]

Algorithm for low grade versus high grade dysplastic nevus.png

In uncertain cases, more specific grading, and/or differentiation from a non-atypical congenital nevus and suspected melanoma, the following table can be used to determine the most fitting diagnosis:

Comparison of congenital pattern nevus, dysplastic nevus and suspected melanoma   edit
Parameter Non-atypical congenital pattern Low-grade dysplastic nevus High-grade dysplastic nevus Suspected melanoma in situ
Mild dysplasia Moderate dysplasia Severe dysplasia
Macroscopic Lateral circumscription[4] Sharp Slightly diminished Moderate Poor
Excised melanoma in situ.jpg
Symmetry[4] Good Often broken Rare
Structural
(Low
mag.)
Delimitation[2] Rarely diffuse Sometimes diffuse Often diffuse
Lentiginous proliferation[notes 4][2] Yes, along with rete pegs Yes, along with and focally between rete pegs Yes, along with and focally between rete pegs Yes partially continuous, multilayered
Histopathology of lentigo maligna.jpg
Bridging[2] Rarely Often
Confluent nests[2] Rarely Sometimes Often Often widespread
Pigment distribution[2] Regular Irregular
Suprabasal presence (less than most superficial third of epidermis) Occasionally centrally[4] No[2] or rarely[4] Occasionally centrally[4] Yes, multifocal[2]
Pagetoid migration including superficial third of epidermis[2] No No Yes, in a maximum of 2 HPF centrally, but not peripherally Yes, multifocal and/or in periphery
Peripheral.
Extended rete pegs Ocassional[4] Yes, regular[2] Yes, varying[2] Yes, often irregular[2] Varying, flattened[2]
Concentric fibrosis Regressive[4] Yes[2] Occasional[4]
Lamellar fibrosis Rarely[2] Often[2] Often pronounced[2] Occasional[4]
Lymphocytic infiltrate[2] Mild, perivascular Mild or moderate, perivascular Varying Varying
Suprapapillary plate involvement No[4] Usually no[4] Often[4] Yes[4]
Cellular
(high
mag.)
Junctional extension[4] Unusual Usual Extensive
Nuclear size[4] Age-related Small Medium Large Medium or large. Pleomorphic[5]
Nuclear pleomorphism[6] Slight Prominent
Chromatin pattern Uniform[4] Condensed[4] Partically expanded[4] Expanded, coarse in some cells[4] Expanded, hyperchromatic, coarse.[4] Usually granular.[6]
Nucleoli[4] Age-related Small Medlium Large Usually[6] large
Mitoses[4] Few superficial Superficial and deep
Histological regression[6][notes 3] Usually Usually not
Percentage of atypical melanocytes[2] <10% About 10 - 50% about 50-90% Usually> 90%
Intradermal melanocytic atypia[2] No Rarely, in superficial part Can be detected in superficial part
Intradermal melanocyte maturation[2] Yes Yes, can be partial Yes, can be partial Variable

In suspected but not certain melanoma in situ, generally perform immunohistochemistry with SOX10, whereby melanocyte nuclear pleomorphism is easier to see.[notes 5]

Report

  • Size
  • Preferably findings included in table.
  • Most likely grade if possible.
See also: General notes on reporting

Notes

  1. For a full list of contributors, see article history. Creators of images are attributed at the image description pages, seen by clicking on the images. See Patholines:Authorship for details.
  2. The excision examples show a normal mole (upper row, benign appearance) and a superficial basal cell carcinoma (lower row, suspected malignancy).
  3. 3.0 3.1 Histological regression is one or more areas within a tumor in which neoplastic cells have disappeared or decreased in number. In this case, this means complete or partial disappearance from areas of the dermis (and occasionally from the epidermis), which have been replaced by fibrosis, accompanied by melanophages, new blood vessels, and a variable degree of inflammation.
    - Ribero, Simone; Gualano, Maria Rosaria; Osella-Abate, Simona; Scaioli, Giacomo; Bert, Fabrizio; Sanlorenzo, Martina; Balagna, Elena; Fierro, Maria Teresa; et al. (2015). "Association of Histologic Regression in Primary Melanoma With Sentinel Lymph Node Status ". JAMA Dermatology 151 (12): 1301. doi:10.1001/jamadermatol.2015.2235. ISSN 2168-6068. 
  4. Lentiginous proliferation is proliferation along the basal layer of the epidermis
  5. SOX10 stains cell nuclei of melanocytes.
    - Miettinen, Markku; McCue, Peter A.; Sarlomo-Rikala, Maarit; Biernat, Wojciech; Czapiewski, Piotr; Kopczynski, Janusz; Thompson, Lester D.; Lasota, Jerzy; et al. (2015). "Sox10—A Marker for Not Only Schwannian and Melanocytic Neoplasms But Also Myoepithelial Cell Tumors of Soft Tissue ". The American Journal of Surgical Pathology 39 (6): 826–835. doi:10.1097/PAS.0000000000000398. ISSN 0147-5185. 

References

  1. There are many variants for the processing of skin excisions. These examples use aspects from the following sources: ". Ochsner J 5 (2): 22–33. 2003. PMID 22826680. PMC: 3399331. Archived from the original. . 
    - With a "standard histologic examination" that, in addition to the lesion, only includes one section from each side along the longest diameter of the specimen.
    - It also shows an example of circular coverage, with equal coverage distance in all four directions.
    - The entire specimen may be submitted if the risk of malignancy is high.
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 2.18 2.19 2.20 Katarzyna Lundmark, Britta Krynitz, Ismini Vassilaki, Lena Mölne, Annika Ternesten Bratel. Histopatologisk bedömning och gradering av dysplastiskt nevus samt gränsdragning mot melanom in situ/melanom (Histopathological assessment and grading of dysplastic nevus and distinction from melanoma in situ/melanoma). KVAST (Swedish Society of Pathology). Retrieved on 2019-09-18.
  3. Pozo, Lucia; Naase, Mahmoud; Cerio, Rino; Blanes, Alfredo; Diaz-Cano, Salvador J. (2001). "Critical Analysis of Histologic Criteria for Grading Atypical (Dysplastic) Melanocytic Nevi ". American Journal of Clinical Pathology 115 (2): 194–204. doi:10.1309/KXJW-1UJE-BPG6-AXBV. ISSN 0002-9173. 
  4. 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 4.19 4.20 4.21 Arumi-Uria, Montserrat; McNutt, N Scott; Finnerty, Bridget (2003). "Grading of Atypia in Nevi: Correlation with Melanoma Risk ". Modern Pathology 16 (8): 764–771. doi:10.1097/01.MP.0000082394.91761.E5. ISSN 0893-3952. 
  5. Christopher S. Hale. Skin melanocytic tumor - Melanoma - Invasive melanoma. Topic Completed: 1 May 2013. Revised: 17 September 2019
  6. 6.0 6.1 6.2 6.3 Husain, Ehab A; Mein, Charles; Pozo, Lucia; Blanes, Alfredo; Diaz-Cano, Salvador J (2011). "Heterogeneous topographic profiles of kinetic and cell cycle regulator microsatellites in atypical (dysplastic) melanocytic nevi ". Modern Pathology 24 (4): 471–486. doi:10.1038/modpathol.2010.143. ISSN 0893-3952.