#dermpathJC January 2019 summary

#dermpathjc January 2019:

Thursday, January 24, 9pm EST

Article discussed: Pigmented Lesions of the Nail Unit

Authors: Nevares-Pomales O, Sarriera-Lazaro C, Barrera-Llaurador J, Santiago-Vazquez M, Lugo-Fagundo N, Sanchez JE, Sanchez JL.

Temporary open access at: https://journals.lww.com/amjdermatopathology/Abstract/2018/11000/Pigmented_Lesions_of_the_Nail_Unit.1.aspx

Summary prepared by Patrick Rush, DO (@DrPatrickRush)

 

Journal Club summary:

This month’s journal club article discussed a topic that gives many of us much consternation, pigmented lesions of the nail unit. The article was a good overall review in many regards; there was discussion (with images) of the clinical features of melanocytic lesions and the concerning signs, as well as a review of the epidemiology, histology, and molecular findings. The learning objectives for the article were very well laid out, and there are accompanying CME questions for obtaining AMA PRA Category 1 credits.

It was a lively discussion, and those active in the discussion overall agreed with the author’s summary and findings.

There were a few take home points from the paper and subsequent discussion, which touched on all aspects:

Embryology:

  • Proximal nail matrix = predominantly dormant melanocytes
  • Distal nail matrix = active and dormant melanocytes (more likely for a melanocytic lesion to arise within this zone)

Epidemiology:

  • Melanocytic macule more common in adults
  • Nevi more common in children

Clinical:

  • Longitudinal melanonychia not always due to a melanocytic lesion (Fungus, drugs, trauma, infection, etc can be causative)
  • Amelanotic subungual melanoma has been reported at rates between 15-50% (while they only comprise 2-8% of melanomas at other sites)

Sampling:

  • Many seem to groan with nail clippings to evaluate for a melanocytic lesion
  • If clippings are sent, if negative they will usually be emblazoned with a caveat in an comment

Histology:

  • Most peoples malignant lesions have been composed of melanoma in situ with invasive melanoma making up the minority.

Immunohistochemistry:

  • SOX10 not as useful in the nail unit as in other parts of the body
  • Mart-1 / Melan A are preferred, and felt to work better
  • Some also order a Fontana Mason in addition

Molecular:

  • Subungual melanoma more commonly harbor KIT mutations
  • Predictions through immunohistochemistry has thus failed to be predictive of molecular aberrations
  • Gold standard for interrogation of KIT mutations remains molecular analysis

Some Highlights from the Evening:

jan1

Jan2

jan3

jan4-e1550170296656.png

Top: nail plate chromomycosis

Bottom: nail plate onychomycosis

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The conversations were great again, with a nice mix of Dermatologists and Pathologists from all over the world. Hope to see you again next time!

 

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