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Nevus
Classification and external resources
Photograph of a nevus on an arm
ICD-10	I78.1
ICD-9	448.1, 216.0-216.9
MeSH	D009506

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. These lesions are commonly named birthmarks and moles. Nevi are benign by definition. 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 differentiated from lentigines (also a type of benign pigmented macule) by the presence of nests of melanocytes, which lentigines (plural form of lentigo) lack.

Contents 1 Classification 1.1 Melanocytic nevus 1.2 Epidermal nevus 1.3 Connective tissue nevus 1.4 Vascular nevus 2 Diagnosis of nevi 3 Normal Evolution or Maturation of Melanocytic Nevus 4 See also 5 References 6 External links

[edit] Classification

Classification is based on cell line of origin. Melanocytic nevi are derived from melanocytes. Epidermal nevi are derived from keratinocytes or derivatives of keratinocytes. Connective tissue nevi are derived from connective tissue cells like adipocyte and fibroblasts. Vascular nevi are derived from structures of the blood vessels. See birthmark for a more complete discussion

[edit] Melanocytic nevus

• Congenital nevus implying a melanocytic nevus present at birth or near birth.
• Acquired melanocytic nevus. Implies 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.

[edit] 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.

[edit] Connective tissue nevus

• Connective tissue nevus: fleshy, deep nodules. Rare.

[edit] Vascular nevus

• Hemangioma (strawberry mark or nevus).
• Nevus flammeus (port-wine stain).
• Spider angioma (nevus araneus).
• Blue Rubber Bleb Nevus Syndrome: dilatation of veins anywhere in the body (both skin and internal organs), usually lethal from internal hemorrhage. It is a very rare genetic disorder.

The term "venous nevus" has recently been proposed.^[2]

[edit] Diagnosis of nevi

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.

[edit] Normal Evolution or Maturation of Melanocytic Nevus

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 occur as the melanocytes clumps and migrates 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]

[edit] See also

• Becker's nevus
• Dysplastic nevus - a melanocytic nevus with abnormal pigment features which can be difficult to distinguish from a melanoma.

[edit] References

[edit] External links

Look up nevus in Wiktionary, the free dictionary.

• Nevus risk factors, symptoms, treatment, and more information
• 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.

v • d • e Diseases of the skin and appendages by morphology Growths Epidermal wart · callus · seborrheic keratosis · acrochordon · molluscum contagiosum · actinic keratosis · squamous cell carcinoma · basal cell carcinoma · merkel cell carcinoma · nevus sebaceous · trichoepithelioma Pigmented Freckles · lentigo · melasma · nevus · melanoma Dermal and subcutaneous epidermal inclusion cyst · hemangioma · dermatofibroma · keloid · lipoma · neurofibroma · xanthoma · Kaposi's sarcoma · infantile digital fibromatosis · granular cell tumor · leiomyoma · lymphangioma circumscriptum · myxoid cyst Rashes With epidermal involvement Eczematous contact dermatitis · atopic dermatitis · seborrheic dermatitis · stasis dermatitis · lichen simplex chronicus · Darier's disease · glucagonoma syndrome · langerhans cell histiocytosis · lichen sclerosus · pemphigus foliaceus · Wiskott-Aldrich syndrome · Zinc deficiency Scaling psoriasis · tinea (corporis · cruris · pedis · manuum · faciei) · pityriasis rosea · secondary syphillis · mycosis fungoides · systemic lupus erythematosus · pityriasis rubra pilaris · parapsoriasis · ichthyosis Blistering herpes simplex · herpes zoster · varicella · bullous impetigo · acute contact dermatitis · pemphigus vulgaris · bullous pemphigoid · dermatitis herpetiformis · porphyria cutanea tarda · epidermolysis bullosa simplex Papular scabies · insect bite reactions · lichen planus · miliaria · keratosis pilaris · lichen spinulosus · transient acantholytic dermatosis · lichen nitidus · pityriasis lichenoides et varioliformis acuta Pustular acne vulgaris · acne rosacea · folliculitis · impetigo · candidiasis · gonococcemia · dermatophyte · coccidioidomycosis · subcorneal pustular dermatosis Hypopigmented tinea versicolor · vitiligo · pityriasis alba · postinflammatory hyperpigmentation · tuberous sclerosis · idiopathic guttate hypomelanosis · leprosy · hypopigmented mycosis fungoides Without epidermal involvement Red Blanchable Erythema Generalized drug eruptions · viral exanthems · toxic erythema · systemic lupus erythematosus Localized cellulitis · abscess · boil · erythema nodosum · carcinoid syndrome · fixed drug eruption Specialized urticaria · erythema (multiforme · migrans · gyratum repens · annulare centrifugum · ab igne) Nonblanchable Purpura Macular thrombocytopenic purpura · actinic purpura Papular disseminated intravascular coagulation · vasculitis Indurated scleroderma/morphea · granuloma annulare · lichen sclerosis et atrophicus · necrobiosis lipoidica Miscellaneous disorders Ulcers Hair telogen effluvium · androgenic alopecia · trichotillomania · alopecia areata · systemic lupus erythematosus · tinea capitis · loose anagen syndrome · lichen planopilaris · folliculitis decalvans · acne keloidalis nuchae Nail onychomycosis · psoriasis · paronychia · ingrown nail Mucous membrane aphthous stomatitis · oral candidiasis · lichen planus · leukoplakia · pemphigus vulgaris · mucous membrane pemphigoid · cicatricial pemphigoid · herpesvirus · coxsackievirus · syphilis · systemic histoplasmosis · squamous cell carcinoma

v • d • e Gonadal tumors, paraganglioma, glomus, nevi and melanomas (ICD-O 8590-8799) Gonadal/ sex cord-gonadal stromal (8590-8679) sex cord (Granulosa cell tumour, Sertoli cell tumor) stroma (Thecoma, Leydig cell tumor) both (Sertoli-Leydig cell tumour, Luteoma) Paragangliomas And Glomus tumors (8680-8719) Neuroendocrine tumor: Paraganglioma (Pheochromocytoma) Vascular tissue neoplasm: Glomus tumor (Glomangiosarcoma) Nevi and melanomas (8720-8799) Nevi Melanocytic/pigmented nevus (Mongolian spot, Blue nevus, Nevus of Ota, Spitz nevus) location (Junctional nevus, Compound nevus) Halo nevus · Dysplastic nevus Melanomas (NE) Superficial spreading melanoma · Nodular melanoma · lentigo (Lentigo maligna/Lentigo maligna melanoma, Acral lentiginous melanoma)

v • d • e Tumors: skin cancer (C43-C44/D22-D23, 172-173/216) Epidermis Basal cell carcinoma · Squamous cell carcinoma (Acanthoma) Bowen's disease Dermis Benign fibrous histiocytoma/dermatofibrosarcoma · Dermatofibrosarcoma protuberans Nevi and melanomas Nevus: Melanocytic nevus · Dysplastic nevus · Halo nevus · Spitz nevus Melanoma: Superficial spreading melanoma · Nodular melanoma · lentigo (Lentigo maligna/Lentigo maligna melanoma, Acral lentiginous melanoma) integument, SF, LCT navs: anat/physio, noncongen/congen/neoplasia, symptoms+signs/eponymous, proc

v • d • e Cardiovascular disease: vascular disease · Circulatory system pathology (I70-I99, 440-456) Arteries, arterioles and capillaries Inflammation Arteritis (Aortitis) · Buerger's disease Arterial occlusive disease/ peripheral vascular disease Arteriosclerosis Atherosclerosis (Foam cell, Fatty streak, Atheroma, Intermittent claudication) · Monckeberg's arteriosclerosis · Arteriolosclerosis (Hyaline, Hyperplastic, oxycholesterol, cholesterol, LDL, trans fat) Stenosis Renal artery stenosis · Carotid artery stenosis Other Fibromuscular dysplasia · Degos disease · Aortoiliac occlusive disease · Raynaud's phenomenon/Raynaud's disease · Erythromelalgia Aneurysm/dissection/ pseudoaneurysm torso: Aortic aneurysm (Thoracic aortic aneurysm, Abdominal aortic aneurysm) · Aortic dissection · Coronary artery aneurysm head/neck: Cerebral aneurysm · Intracranial berry aneurysm · Carotid artery dissection · Vertebral artery dissection · Familial aortic dissection Vascular malformation Arteriovenous fistula · Telangiectasia (Hereditary hemorrhagic telangiectasia) Vascular nevus Spider angioma · Halo nevus · Cherry hemangioma Veins Inflammation Phlebitis Venous thrombosis/ Thrombophlebitis primarily lower limb (Deep vein thrombosis) abdomen (May-Thurner syndrome, Portal vein thrombosis, Budd-Chiari syndrome, Renal vein thrombosis) upper limb/torso (Paget-Schroetter disease, Mondor's disease) head (Cerebral venous sinus thrombosis) Post-thrombotic syndrome Varicose veins Varicocele · Gastric varices · Portacaval anastomosis (Hemorrhoid, Esophageal varices, Caput medusae) Other Superior vena cava syndrome · Inferior vena cava syndrome · Venous ulcer · Chronic venous insufficiency · Chronic cerebrospinal venous insufficiency Arteries or veins Vasculitis · Thrombosis · Embolism (Pulmonary embolism, Cholesterol embolism, Paradoxical embolism) · Angiopathy (Macroangiopathy, Microangiopathy) Blood pressure Hypertension Hypertensive heart disease · Hypertensive nephropathy · Essential hypertension  · Secondary hypertension (Renovascular hypertension) · Pulmonary hypertension · Malignant hypertension · Benign hypertension · Systolic hypertension · White coat hypertension Hypotension Orthostatic hypotension vascular navs: anat/physio/dev, noncongen/systemic vasculitis/congen/neoplasia, symptoms+signs/eponymous, proc