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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/09/24 04:36:51」(JST)

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Nevus, also known as a mole,^[1] is the medical term for sharply circumscribed^[2] and chronic lesions of the skin or mucosa. These lesions are commonly named birthmarks or beauty marks. Nevi are benign by definition. However, 25% of malignant melanomas (a skin cancer) arise from pre-existing nevi.^[3] Using the term nevus and nevi loosely, most physicians and dermatologists are actually referring to a variant of nevus called the "melanocytic nevus", which are composed of melanocytes. Histologically, melanocytic nevi are distinguished from lentigines (also a type of benign pigmented macule) by the presence of nests of melanocytes, which lentigines (plural form of lentigo) lack.

Classification

Epidermal nevi are derived from keratinocytes or derivatives of keratinocytes. Connective tissue nevi are derived from connective tissue cells like adipocytes and fibroblasts. Vascular nevi are derived from structures of the blood vessels. See birthmark for a more complete discussion

Melanocytic nevus

Congenital nevus: a melanocytic nevus present at birth or near birth.
Acquired melanocytic nevus: a melanocytic nevus acquired later in life, and not at or near birth. Most melanocytic nevi are of the acquired variety.
Melanocytic nevus (nevomelanocytic nevus, nevocellular nevus): benign proliferation of melanocytes, the skin cells that make the brown pigment melanin. Hence, most nevi are brown to black. They are very common; almost all adults have at least one, usually more. They may be congenital or acquired (usually at puberty).
Dysplastic nevus: usually an acquired melanocytic nevus with abnormal features making it difficult to distinguish from a melanoma. It can be a marker for an individual at risk for developing melanomas.

Epidermal nevus

Epidermal nevus: congenital, flesh-colored, raised or warty, often linear lesion, usually on the upper half of the body.
Nevus sebaceus: variant of epidermal nevus on the scalp presenting as a hairless, fleshy or yellowish area.

Connective tissue nevus

Connective tissue nevus: fleshy, deep nodules. Rare.

Vascular nevus

Hemangioma (strawberry mark or nevus).

Diagnosis of nevi

A dermatoscope

A modern polarized dermatoscope

Clinical diagnosis of a melanocytic nevus from other nevi can be made with the naked eye using the ABCD guideline, or using dermatoscopy. The main concern is distinguishing between a benign nevus, a dysplastic nevus, and a melanoma. Other skin tumors can resemble a melanocytic nevus clinically, such as a seborrheic keratosis, pigmented basal cell cancer, hemangiomas, and sebaceous hyperplasia. A skin biopsy is required when clinical diagnosis is inadequate or when malignancy is suspected.

Normal evolution or maturation of melanocytic nevi

All melanocytic nevi will change with time - both congenital and acquired nevi. The "normal" maturation is evident as elevation of the lesion from a flat macule to a raised papule. The color change occurs as the melanocytes clump and migrate from the surface of the skin (epidermis) down deep into the dermis. The color will change from even brown, to speckled brown, and then losing the color and becomes flesh colored or pink. During the evolution, uneven migration can make the nevi look like melanomas, and dermatoscopy can help in differentiation between the benign and malignant lesions.^[4]

Etymology

A nevus may also be spelled naevus. The plural is nevi or naevi. The word is from nævus, Latin for "birthmark".

References

^ "Common Moles, Dysplastic Nevi, and Risk of Melanoma". National Cancer Institute. November 1, 2011. Retrieved 30 June 2015.
^ "nevus" at Dorland's Medical Dictionary
^ Sam, Amir H.; James T.H. Teo (2010). Rapid Medicine. Wiley-Blackwell. ISBN 1405183233.
^ [1]^{[dead link]}

External links

Atlas of Pathology Section of a melanocytic nevus
eMedicine: Mole or Melanoma? Tell-Tale Signs in Benign Nevi and Malignant Melanoma: Slideshow
Nevus Outreach, Inc.
Pediatric plastic surgeon helps little girl with nevus NBC LA

English Journal

DICER1 syndrome can mimic different genetic tumor predispositions.

Mehraein Y1, Schmid I2, Eggert M1, Kohlhase J3, Steinlein OK4.
Cancer letters.Cancer Lett.2016 Jan 28;370(2):275-8. doi: 10.1016/j.canlet.2015.11.002. Epub 2015 Nov 11.
DICER1, a RNAse endonuclease involved in the processing of siRNA and microRNA, is known to play a pivotal role in the post-transcriptional regulation of gene expression. Germ line mutations in the DICER1 gene increase the risk for different types of tumors. At present, DICER1 syndrome is an establis
PMID 26577641

Update on Thin Melanoma: Outcome of an International Workshop.

Mihic-Probst D1, Shea C, Duncan L, de la Fouchardiere A, Landman G, Landsberg J, Ven den Oord J, Lowe L, Cook MG, Jung Yun S, Clarke L, Messina J, Elder DE, Barnhill RL.
Advances in anatomic pathology.Adv Anat Pathol.2016 Jan;23(1):24-9. doi: 10.1097/PAP.0000000000000100.
The following communication summarizes the proceedings of a 1-day Workshop of the International Melanoma Pathology Study Group, which was devoted to thin melanoma. The definitions and histologic criteria for thin melanoma were reviewed. The principal differential diagnostic problems mentioned includ
PMID 26645459

Immunohistochemical Detection of NRASQ61R Mutation in Diverse Tumor Types.

Dias-Santagata D1, Su Y1, Hoang MP2.
American journal of clinical pathology.Am J Clin Pathol.2016 Jan;145(1):29-34. doi: 10.1093/ajcp/aqv015.
OBJECTIVES: Testing for NRAS mutation at codon Q61 is of therapeutic, prognostic, and diagnostic importance for metastatic melanoma, thyroid carcinoma, and colorectal carcinoma. Immunohistochemistry for NRASQ61R, the most common NRAS mutation, offers several practical advantages over current molecul
PMID 26712868

Japanese Journal

生下時より認められた先天性頸部遺残軟骨の4例

榊原堅式,佐藤陽子,中前勝視,三井章,桑原義之
日本臨床外科学会雑誌 = The journal of the Japan Surgical Association 74(2), 357-361, 2013-02-25
NAID 10031165568

生下時より認められた先天性頸部遺残軟骨の4例

榊原堅式,佐藤陽子,中前勝視,三井章,桑原義之
日本臨床外科学会雑誌 74(2), 357-361, 2013
生下時より認められた，先天性頸部遺残軟骨の4例を経験したので報告する．4例とも男児で，生下時より，胸鎖乳突筋の前縁に硬い軟骨様の腫瘤を触知した．左側下方が2例，左側上方が1例，右側下方が1例であった．大きさは，1から1.5cm大で，硬く，1歳から2歳時に摘出術を施行した．いずれも，深部は胸鎖乳突筋内で摘出でき，病理組織の検査結果は，軟骨組織と診断された．1例に鼠径ヘルニアを認めた以外は，他の外表奇 …
NAID 130004518659

Phakomatosis Pigmentovascularis Type IIB : A Case Report

THENG Thiam Seng Colin,SUJITH Prasad W. Kumarasinghe
Journal of dermatology 31(5), 415-418, 2004-05-01
NAID 10016129236

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