Atypical Nevus

Aka: Atypical Nevus, Atypical Nevi, Atypical Mole, Clark Nevus, Dysplastic Nevus, Dysplastic Nevi, Compound Nevus with Associated Architectural Disorder

II. Epidemiology

  1. Onset after childhood (contrast with common nevi)
    1. Atypical Nevi have onset at Puberty
    2. Atypical Nevi continue to form and develop until age 40-50 years
  2. Chest and back are most commonly involved in men
  3. Legs are most commonly affected in women
  4. Malignant melanoma Incidence is increasing (approaches 3% lifetime risk)
    1. Maintain a higher level of suspicion
  5. Atypical Nevus Prevalence
    1. Fair skin: 2-8%
    2. Skin of Color: <2%

III. Classification: Spectrum of Nevus findings

  1. Compound Nevus
  2. Compound Nevus with Associated Architectural Disorder
    1. Mild cytologic atypia
    2. Severe cytologic atypia
  3. Atypical melanocytic hyperplasia (Melanoma in-situ)
  4. Melanoma

IV. Risk Factors: Correlation to Melanoma

  1. See Melanoma Risk Factors
  2. Lifetime risk of Melanoma in caucusians: 0.8%
  3. Small Nevi (2-5 mm)
    1. Under 25 small nevi: RR=1.0
    2. Over 100 small nevi: RR=3.1
  4. Larger Non-Dysplastic Nevi (>5 mm)
    1. Over 9 non-Dysplastic Nevi: RR=2.3
  5. Dysplastic Nevi
    1. One Dysplastic Nevi: RR=2.2
    2. Over 9 Dysplastic Nevi: RR=12.0
  6. Atypical Moles and lifetime risk of Melanoma
    1. Atypical Moles and no Family HistoryMelanoma: 6%
    2. Atypical Moles and prior Melanoma: 10% (risk of second Melanoma)
  7. Atypical Mole Syndrome (FAM-M Syndrome, B-K Mole Syndrome)
    1. Ten year risk of Melanoma exceeds 10%
    2. Lifetime risk of Melanoma approaches 100%

V. Signs: Abnormal moles (Mnemonic: ABCDE)

  1. Asymmetry
    1. Non-geometric outline - i.e. not circular or eliptical
    2. One half of lesion differs from the other side
  2. Border irregular or indistinct
  3. Color non-uniform
    1. Variable pigmentation involving at least 2 different colors
  4. Diameter over 5-6 mm
    1. Pencil eraser size
  5. Evolution of lesion
    1. Recent change in size or features

VI. Signs: Other abnormal findings

  1. Associated itch or altered sensation
  2. Inflammation at lesion site
  3. Oozing or crusting lesions
  4. Ugly duckling size
    1. One lesion distinctly different than others
  5. Atypical Nevi are flat, but may have raised center (fried-egg sign)

VII. Signs: Distribution

  1. Common nevi
    1. Above the waist
    2. Sun exposed areas
  2. Atypical Nevi
    1. Back (most common)
    2. Arms and legs
    3. Area typically shielded from the sun
      1. Female Breast
      2. Scalp
      3. Buttock
      4. Groin

VIII. Diagnostics: Dermoscopy

  1. See Dermoscopy
  2. Handheld dermatoscope (10X magnifier) applied over pre-oiled skin
  3. Helps identify Atypical Nevus patterns (reticular, globular, homogenous)
  4. Online Dermoscopy tutorial
    1. http://www.dermoscopy.org/atlas/base.htm

IX. Labs: Histology

  1. Atypical Melanocytes with large hyperchromatic nucleus
  2. Melanocytes collect in nests or groups
  3. Lymphocyte infiltration (patchy)
  4. Concentric Eosinophilic fibroplasia

X. Protocol: Lesions to Act on (Biopsy or Refer)

  1. Very high risk patients without monitoring plan
    1. See Melanoma Risk Factors
    2. Annual skin exam
  2. Suspicious lesions ("ugly duckling sign" - one mole that stands out)
    1. Eroded, crusted, ulcerated or bleeding >3 weeks
    2. Translucent Papules with telangiectasia
    3. New mole after age 30 years
    4. Keratotic lesions on face, ears, lips or genitalia
      1. Not typical for Seborrheic Keratoses
    5. Asymmetric, irregularly bordered lesions (see signs above)
      1. Multicolored or irregularly pigmented
      2. Changing in size, shape, surface, or color
    6. Black lesions on non-sun exposed skin
      1. Persons with white or light tan colored skin

XI. Protocol: Lesions to Ignore (Reassure patient)

  1. Benign lesions
    1. Seborrheic Keratosis
    2. Dermatofibroma
    3. Dermal Nevus
    4. Cherry Angioma
    5. Freckle
    6. Lentigo
    7. Cafe-Au-Lait Spot
  2. Lesions present less than 3 weeks
  3. Lesions <3mm, Macular, and without change
  4. Lesions <6mm without change and no act on criteria

XII. Protocol: Lesions to Watch (Reevaluate at 2 and 6 months)

  1. All lesions not classified as Ignore or Act on

XIII. Precautions

  1. Biopsy pearls
    1. Full thickness specimen is critical
      1. Punch Biopsy, Excisional Biopsy or Saucerization Biopsy
      2. Do not Shave Biopsy any lesion suspected of Melanoma
    2. Excisional Biopsy with 2 mm margin is preferred
    3. Document dimensions at time of biopsy
      1. Original lesion size
      2. Surgical margin
      3. Residual lesion size
  2. Reexcise lesions if moderate or severe cytologic atypia on biopsy and positive margins
    1. Margins should be at least 2 mm for moderate dysplasia (5 mm if severe atypia)
  3. Pseudo-Melanoma
    1. Re-excision of previously excised nevi may give False Positive appearance of Melanoma to pathologist
    2. Alert pathologists when submitting a sample from a previously biopsied site

XIV. References

  1. Habif (2003) Clinical Dermatology, 4th ed.. Mosby, p. 773-813
  2. Cyr (2008) Am Fam Physician 78(6):735-42 [PubMed]
  3. Naeyaert (2003) N Engl J Med 349:2233-40 [PubMed]
  4. Perkins (2015) Am Fam Physician 91(11): 762-7 [PubMed]
  5. Tucker (1997) JAMA 277:1439-44 [PubMed]
  6. Weinstock (1996) J Am Acad Dermatol 34(6): 1063-6 [PubMed]
  7. Shenenberger (2012) Am Fam Physician 85(2): 161-8 [PubMed]

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Related Studies

Ontology: Dysplastic Nevus (C0205748)

Definition (NCI_NCI-GLOSS) A type of nevus (mole) that looks different from a common mole. A dysplastic nevus is often larger with borders that are not easy to see. Its color is usually uneven and can range from pink to dark brown. Parts of the mole may be raised above the skin surface. A dysplastic nevus may develop into malignant melanoma (a type of skin cancer).
Definition (NCI) Solitary or multiple, slightly raised, pigmented lesions with irregular borders, usually measuring more than 0.6cm in greatest dimension. Morphologically, there is melanocytic atypia and the differential diagnosis from melanoma may be difficult. Patients are at an increased risk for the development of melanoma.
Concepts Neoplastic Process (T191)
MSH D004416
ICD10 M8727/0 , D22
SnomedCT 189759009, 61814002, 254818000
English Nevus, Dysplastic, Nevi, Dysplastic, [M] Dysplastic naevus, [M] Dysplastic nevus, dysplastic nevus (diagnosis), dysplastic nevus, Clark Nevus, atypical nevus, atypical naevus, atypical nevis, dysplastic nevi, dysplastic naevus, naevus dysplastic, dysplastic nevis, atypical nevi, Nevus with Architectural Disorder, Dysplastic naevus (disorder), [M]Dysplastic naevus, [M]Dysplastic nevus, Atypical naevus, Atypical naevus of skin, Atypical nevus, Atypical nevus of skin, Dysplastic naevus, Dysplastic naevus of skin, Dysplastic nevus, Dysplastic nevus of skin, DN - Dysplastic naevus, DN - Dysplastic nevus, Dysplastic nevus (morphologic abnormality), Dysplastic nevus of skin (disorder), Dysplastic Nevus, NAD, Clark's Nevus, Lentiginous Nevus, Nevus with Architectural Disorder and Cytologic Atypia of Melanocytes, Atypical Nevus, Dysplastic Nevi
French Naevus dysplasiques, Naevus atypiques, Naevus dysplasique, Naevus de Clark
German Nävus, dysplastischer, dysplastischer Naevus
Spanish Nevus displásico, nevo atípico, nevo cutáneo atípico, nevo cutáneo displásico (trastorno), nevo cutáneo displásico, nevo displásico (anomalía morfológica), nevo displásico, Nevo Displástico
Portuguese Nevo displásico, Nevo Displásico
Dutch dysplastische naevus, Dysplatische-naevussyndroom
Czech Dysplastický névus
Japanese ｲｹｲｾｲﾎﾞﾊﾝ, 異形成母斑
Hungarian Dysplasiás naevus, Dysplasiás nevus
Norwegian Dysplastisk nevus
Italian Nevi displastici, Nevo displastico
Derived from the NIH UMLS (Unified Medical Language System)

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