Nevi (singular nevus), also known as “ moles Moles Primary Skin Lesions,” are benign Benign Fibroadenoma neoplasms Neoplasms New abnormal growth of tissue. Malignant neoplasms show a greater degree of anaplasia and have the properties of invasion and metastasis, compared to benign neoplasms. Benign Bone Tumors of the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions. Nevus is a non-specific medical term because it encompasses both congenital Congenital Chorioretinitis and acquired lesions, hyper- and hypopigmented lesions, and raised or flat lesions. Additionally, nevi can be found within different depths of the layers of the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions and originate from various types of cells (e.g., melanocytic, connective tissue Connective tissue Connective tissues originate from embryonic mesenchyme and are present throughout the body except inside the brain and spinal cord. The main function of connective tissues is to provide structural support to organs. Connective tissues consist of cells and an extracellular matrix. Connective Tissue: Histology, vascular). Nevi also have a wide variety of characteristic forms, which must be well understood in order to differentiate nevi from malignant melanoma Melanoma Melanoma is a malignant tumor arising from melanocytes, the melanin-producing cells of the epidermis. These tumors are most common in fair-skinned individuals with a history of excessive sun exposure and sunburns. Melanoma. In this concept page, we will cover the basic classifications and most common types of nevi as well as the clinical criteria used to assess them.
Last updated: 8 Jan, 2021
A nevus (plural nevi) is a benign Benign Fibroadenoma neoplasm of the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions:
Nevi can be classified in various ways, according to several factors that are not mutually exclusive:
From left to right: reticular, starburst, and globular types of nevi
Image: “Clark nevus” by the Department of Automatics and Biomedical Engineering, AGH University of Science and Technology, Aleja Mickiewicza 30, 30-059 Krakow, Poland. License: CC BY 4.0.Congenital Congenital Chorioretinitis melanocytic nevus: a brown well-circumscribed papule Papule Elevated lesion < 1 cm in diameter Generalized and Localized Rashes on the nose Nose The nose is the human body’s primary organ of smell and functions as part of the upper respiratory system. The nose may be best known for inhaling oxygen and exhaling carbon dioxide, but it also contributes to other important functions, such as tasting. The anatomy of the nose can be divided into the external nose and the nasal cavity. Nose and Nasal Cavity: Anatomy that developed shortly after birth
Image: “ Congenital Congenital Chorioretinitis melanocytic nevus” by M. Sand et al AL Amyloidosis. License: CC BY 2.0.Mongolian spot or congenital Congenital Chorioretinitis dermal melanocytosis over the lumbar and gluteal regions
Image: “Enorme tache mongoloïde” by Service de Pédiatrie, Hôpital Militaire d’Instruction Mohamed V, Université Med V, Souissi, Maroc. License: CC BY 2.0.Congenital Congenital Chorioretinitis nevus of Ito: blue-gray macule Macule Nonpalpable lesion < 1 cm in diameter Generalized and Localized Rashes, representing a benign Benign Fibroadenoma dermal melanocytosis that preferentially affects areas innervated by the posterior supraclavicular nerves
Image: “Nevus of Ito” by the U.S. National Library of Medicine. License: CC BY 4.0.Congenital Congenital Chorioretinitis nevus of Ota: benign Benign Fibroadenoma dermal melanocytosis that preferentially affects areas innervated by the 1st and 2nd division of the trigeminal nerve Trigeminal nerve The 5th and largest cranial nerve. The trigeminal nerve is a mixed motor and sensory nerve. The larger sensory part forms the ophthalmic, mandibular, and maxillary nerves which carry afferents sensitive to external or internal stimuli from the skin, muscles, and joints of the face and mouth and from the teeth. Most of these fibers originate from cells of the trigeminal ganglion and project to the trigeminal nucleus of the brain stem. The smaller motor part arises from the brain stem trigeminal motor nucleus and innervates the muscles of mastication. The 12 Cranial Nerves: Overview and Functions. A congenital Congenital Chorioretinitis nevus of Ota often affects the sclerae.
Image: “Nevus” by Luninsky. License: CC BY 3.0.Type | Description | Presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor |
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Junctional nevi |
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Compound nevi | Nevus cells found at the dermo-epidermal junction and intradermally, smaller cells that produce less melanin Melanin Insoluble polymers of tyrosine derivatives found in and causing darkness in skin (skin pigmentation), hair, and feathers providing protection against sunburn induced by sunlight. Carotenes contribute yellow and red coloration. Seborrheic Keratosis |
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Intradermal nevi | Nevus cells found intradermally, small cells that produce little to no melanin Melanin Insoluble polymers of tyrosine derivatives found in and causing darkness in skin (skin pigmentation), hair, and feathers providing protection against sunburn induced by sunlight. Carotenes contribute yellow and red coloration. Seborrheic Keratosis |
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Natural history of acquired melanocytic nevi
Common nevi (“
moles
Moles
Primary Skin Lesions”) begin as uniformly tan or brown macules, 1 to 2
mm
MM
Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies.
Multiple Myeloma in diameter (a), expand to a larger
macule
Macule
Nonpalpable lesion < 1 cm in diameter
Generalized and Localized Rashes (b), progress to a pigmented
papule
Papule
Elevated lesion < 1 cm in diameter
Generalized and Localized Rashes that may be minimally (c) or obviously (d) elevated above the surface of the
skin
Skin
The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue.
Skin: Structure and Functions, and terminate as a pink or flesh-colored
papule
Papule
Elevated lesion < 1 cm in diameter
Generalized and Localized Rashes (e).
Acquired melanocytic nevi are junctional (a, b), compound (c, d), and dermal (e) nevi, respectively. Note their smooth borders, uniform coloring, and clear demarcation from the surrounding
skin
Skin
The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue.
Skin: Structure and Functions with smooth borders.
Acquired melanocytic nevi are usually < 5
mm
MM
Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies.
Multiple Myeloma in diameter.
Based on clinical appearance, a typical benign Benign Fibroadenoma nevus should have the following characteristics:
A dysplastic or atypical nevus is a benign melanocytic nevus with an appearance that differs from common nevi or “ moles Moles Primary Skin Lesions” based on the ABCDE criteria ( asymmetry Asymmetry Examination of the Upper Limbs, border irregularity, color variation, diameter ≥ 6 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma, and evolution):
Common ( benign Benign Fibroadenoma) nevi | Atypical nevi | Melanoma Melanoma Melanoma is a malignant tumor arising from melanocytes, the melanin-producing cells of the epidermis. These tumors are most common in fair-skinned individuals with a history of excessive sun exposure and sunburns. Melanoma (m.) | |
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Asymmetry Asymmetry Examination of the Upper Limbs (A) | Symmetric (a straight line drawn through the center of the lesion gives 2 mirror images) |
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Border (B) | Smooth, well-defined border | Irregular margin with ill-defined border | Irregular margin with ill-defined border |
Color (C) | Uniform color or regular Regular Insulin color pattern (e.g., speckled or starburst) | Variegated color or varying shades of color | Variegated color or varying shades of color |
Diameter (D) | < 5 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma | Often ≥ 5 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma | > 6 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma |
Evolution (E) | Stable or slow growth |
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Location (not part of criteria, but an important factor) | Concentrated on sun-exposed sites |
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Depends on type:
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A dysplastic nevus presenting as a maculopapular Maculopapular Dermatologic Examination lesion. The central portion is the papular area, barely perceptible in this photograph. Note the irregular and indistinct border and the variegated color pattern of brown and pink.
Image: “Dysplastic nevi” by the National Cancer Institute. License: Public domain.
Melanoma
Melanoma
Melanoma is a malignant tumor arising from melanocytes, the melanin-producing cells of the epidermis. These tumors are most common in fair-skinned individuals with a history of excessive sun exposure and sunburns.
Melanoma and dysplastic nevus.
A: clinical overview of the patient;
B: lesion 1:
melanoma
Melanoma
Melanoma is a malignant tumor arising from melanocytes, the melanin-producing cells of the epidermis. These tumors are most common in fair-skinned individuals with a history of excessive sun exposure and sunburns.
Melanoma, naked-eye clinical close-up;
C: lesion 1:
melanoma
Melanoma
Melanoma is a malignant tumor arising from melanocytes, the melanin-producing cells of the epidermis. These tumors are most common in fair-skinned individuals with a history of excessive sun exposure and sunburns.
Melanoma, digital
dermoscopy
Dermoscopy
A noninvasive technique that enables direct microscopic examination of the surface and architecture of the skin.
Seborrheic Keratosis view;
D: lesion 2: dysplastic nevus, naked-eye clinical close-up;
E: lesion 2: dysplastic nevus, digital
dermoscopy
Dermoscopy
A noninvasive technique that enables direct microscopic examination of the surface and architecture of the skin.
Seborrheic Keratosis view.