Blue nevus

{{short description|Type of melanocytic tumor}}

{{Infobox medical condition (new)

| name = Blue nevus

| synonyms = Blue neuronevus, dermal melanocytoma, nevus coeruleus, nevus bleu

| image = Blue Nevus (crop).jpg

| width = 150

| caption = Blue nevus

| pronounce =

| field = Dermatology

| symptoms = Single well-defined blue-black bump| complications = Rarely malignant transformation

| onset =

| duration =

| types = Dendritic, cellular

| causes = Unclear

| risks =

| diagnosis = Visualisation, dermoscopy

| differential = Dermatofibroma, melanoma{{MeshName|Blue+Nevi}}

| prevention =

| treatment = Monitoring, excision

| medication =

| prognosis = Good

| frequency = Female>male

| deaths =

}}

A blue nevus is a type of coloured mole, typically a single well-defined blue-black bump.{{cite book |author=Rapini, Ronald P. |author2=Bolognia, Jean L. |author3=Jorizzo, Joseph L. |title=Dermatology: 2-Volume Set |publisher=Mosby |location=St. Louis |year=2007 |pages=1722 |isbn=978-1-4160-2999-1 }}{{cite book|last=Johnstone |first=Ronald B.|title=Weedon's Skin Pathology Essentials |url=https://books.google.com/books?id=NTE_DAAAQBAJ|year=2017|publisher=Elsevier |isbn=978-0-7020-6830-0|edition=2nd|page=545|chapter=32. Lentigines and melanomas}}

The blue colour is caused by the pigment being deep in the skin.{{cite web |title=Blue naevus |url=https://dermnetnz.org/topics/blue-naevus |website=dermnetnz.org |access-date=21 October 2021 |language=en}}

Diagnosis is by visualisation and dermoscopy. A biopsy is sometimes performed, or the whole lesion surgically removed.{{cite journal |last1=Austad |first1=Steve S. |last2=Athalye |first2=Leela |title=Blue Nevus |journal=StatPearls |date=2021 |url=https://www.ncbi.nlm.nih.gov/books/NBK549774/ |publisher=StatPearls Publishing|pmid=31747181 }} The outcome is generally good but there is a small chance of cancerous transformation. Differential diagnosis includes dermatofibroma and melanoma.

Blue nevi are more common in females than males. It was first studied in 1906 by Tièche, a student of Josef Jadassohn.{{cite journal |last1=Sreeremya |first1=S. |title=Blue Nevus |journal=International Journal of Molecular Biotechnology |date=17 April 2018 |volume=4 |issue=1 |pages=1–4 |doi=10.37628/ijmb.v4i1.255 |doi-broken-date=1 November 2024 |url=http://biotech.journalspub.info/?journal=IJMB&page=article&op=view&path%5B%5D=255 |language=en}}