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母斑(ぼはん)(先天性のあざ・ほくろ・そばかすなど)

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/10/28 19:34:10」(JST)

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Nevus (or naevus, plural nevi or naevi, from nævus, Latin for "birthmark") is the medical term for sharply circumscribed^[1] 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.^[2] 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.^[3]

References

^ "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

Look up nevus in Wiktionary, the free dictionary.

Wikimedia Commons has media related to Nevus.

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

UpToDate Contents

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1. 非定型母斑（異形成母斑） atypical dysplastic nevi
2. 色素細胞性母斑（ほくろ）以外の良性色素性皮膚病変 benign pigmented skin lesions other than melanocytic nevi moles
3. スピッツ母斑様色素細胞性腫瘍（スピッツ母斑およびatypical Spitz
tumor） spitzoid melanocytic neoplasms spitz nevus and atypical spitz tumors
4. 後天性色素性母斑（ほくろ） acquired melanocytic nevi moles
5. 皮膚の良性病変の概要 overview of benign lesions of the skin

English Journal

Breast lipofilling: A new treatment of Becker nevus syndrome.

Ho Quoc C1, Fakiha M2, Meruta A2, Dlimi C2, Piat JM3, Delay E2.
Annales de chirurgie plastique et esthétique.Ann Chir Plast Esthet.2015 Aug;60(4):336-9. doi: 10.1016/j.anplas.2015.02.001. Epub 2015 Mar 3.
INTRODUCTION: The association of Becker's nevus with other cutaneous, musculoskeletal or maxillofacial anomalies is called Becker nevus syndrome. Ipsilateral breast hypoplasia is the main reason for female patients to seek medical advice. We present two clinical cases of Becker nevus syndrome with t
PMID 25746302

Selected Cases From the Arkadi M. Rywlin International Pathology Slide Series: Granular Cell Nevus of Congenital Type: A Melanocytic Proliferation Exhibiting Distinct Morphologic, Immunohistochemical, and Ultrastructural Features.

De Pellegrin A1, Luzar B, Suster S, Falconieri G.
Advances in anatomic pathology.Adv Anat Pathol.2015 Jul;22(4):273-7. doi: 10.1097/PAP.0000000000000080.
A case of combined melanocytic nevus characterized by extensive granular cytoplasmic changes is described. Clinically, the lesion presented as an irregular, slightly asymmetric, and raised pigmented lesion of back with indistinct borders. Microscopically, a congenital pattern of distribution of mela
PMID 26050265

Neurocristic Hamartoma With Lymph Node Involvement: A Diagnostic Dilemma.

Goyal S1, Arora VK, Gupta L, Singal A, Kaur N.
The American Journal of dermatopathology.Am J Dermatopathol.2015 Jul;37(7):e87-92. doi: 10.1097/DAD.0000000000000155.
Neurocristic hamartoma (NH) is a rare dermal melanocytic lesion that is formed due to the aberrant development of neural crest-derived melanocytes during their course of migration through the dermis at the time of embryogenesis. Here, we describe a case of NH in a 6-year-old boy who clinically prese
PMID 26091517