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Skin melanocytic tumor

Melanoma

Pediatric melanoma


Idy Tam, M.D.
Bethany R. Rohr, M.D.

Last author update: 9 April 2024
Last staff update: 18 April 2024

Copyright: 2019-2024, PathologyOutlines.com, Inc.

PubMed Search: Pediatric melanoma

Idy Tam, M.D.
Bethany R. Rohr, M.D.
Page views in 2024 to date: 120
Table of Contents
Definition / general | Essential features | Terminology | ICD coding | Epidemiology | Sites | Pathophysiology | Etiology | Clinical features | Diagnosis | Prognostic factors | Case reports | Treatment | Clinical images | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Molecular / cytogenetics description | Molecular / cytogenetics images | Sample pathology report | Differential diagnosis | Board review style question #1 | Board review style answer #1 | Board review style question #2 | Board review style answer #2 | Board review style question #3 | Board review style answer #3
Cite this page: Tam I, Rohr BR. Pediatric melanoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skintumormelanocyticmelanomapediatric.html. Accessed April 26th, 2024.
Definition / general
  • Pediatric melanoma is defined as melanoma occurring in patients younger than or equal to 19 years of age (Pediatrics 2013;131:846)
Essential features
Terminology
ICD coding
  • ICD-10: C43.9 - malignant melanoma of skin, unspecified
  • ICD-11
    • 2C30.0 - superficial spreading melanoma, primary
    • 2C30.Y - other specified melanoma of skin
    • 2C30.Z - melanoma of skin, unspecified
Epidemiology
  • Pediatric melanoma is rare, accounting for 1 - 3% of all pediatric malignancies (J Eur Acad Dermatol Venereol 2023;37:1758)
    • ~1 - 4% of all melanomas occur in pediatric patients
    • Conventional melanomas (i.e., superficial spreading and nodular) are most common
      • 58.1% in children < 11 years and 86.7% in children 12 - 19 years
    • Spitz and spitzoid melanomas are second most common
      • 35.5% in children < 11 years and 12.4% in children 12 - 19 years
    • Melanoma arising in giant congenital nevi are least common
      • 6.5% in children < 11 years and 0.9% in children 12 - 19 years
  • Genetic factors including (J Eur Acad Dermatol Venereol 2023;37:1758)
    • Inherited deoxyribonucleic acid (DNA) repair defects
    • Family history of melanoma
    • Light skinned individuals
    • Increased total number of nevi
    • Congenital melanocytic nevi with risks correlating with size (> 40 cm) and number
  • Cumulative sun damage (J Eur Acad Dermatol Venereol 2023;37:1758)
    • Extensive sun exposure and sunburns
    • Indoor tanning
Sites
Pathophysiology
Etiology
Clinical features
  • Childhood melanomas, particularly in prepubertal cases, deviate from conventional ABCDE criteria (asymmetry, border irregularity, color variegation, diameter ≥ 6 mm, evolving lesion) (N Engl J Med 1995;332:656)
    • Pink or reddish, dome shaped papule
    • Amelanotic, nodular lesion
    • Often mimics benign lesions (i.e., symmetric, pigmented lesions with regular borders)
    • Modified ABCD criteria: amelanotic, bleeding / bump, color uniformity, de novo / any diameter (N Engl J Med 1995;332:656)
  • Melanoma arising in congenital melanocytic nevi features (Br J Dermatol 2006;155:1, J Eur Acad Dermatol Venereol 2023;37:32)
    • Giant congenital melanocytic nevi (> 40 cm)
    • Arising in deeper nevi
    • Predominantly observed on the trunk region
    • Giant congenital melanocytic nevi that extend across the midline of the spine
    • Presence of satellite nevi
    • Melanomas may also arise within the central nervous system
Diagnosis
Prognostic factors
Case reports
Treatment
Clinical images

Images hosted on other servers:
Pediatric superficial spreading melanoma

Pediatric superficial spreading melanoma

Dermoscopy of melanoma in adolescent

Dermoscopy of melanoma in adolescent

Spitzoid melanoma in child

Spitzoid melanoma in child

Microscopic (histologic) description
  • Conventional melanoma
    • Superficial spreading (Arch Pathol Lab Med 2020;144:500)
      • Radial followed by horizontal growth phase
      • Pagetoid growth scattered in the epidermis
      • Nests vary in size, shape and distribution
        • Not evenly spaced and not confined to tips of rete
      • Asymmetrical
      • Fails to mature from superficial to deep
      • Cytological atypia and mitoses
      • Can have lymphoid infiltrate at the base
      • With or without ulceration
    • Nodular (Arch Pathol Lab Med 2020;144:500, Ital J Dermatol Venerol 2021;156:300)
      • May be polypoid and exophytic
      • Lacks radial growth
      • Tumor size often > 10 mm
      • Cytologic atypia and mitoses
      • Necrosis
      • With or without ulceration
    • Pathologic stage classification American Joint Committee on Cancer (AJCC) guidelines, eighth edition (2018) (Ital J Dermatol Venerol 2021;156:300)
      • Tumor (Breslow) depth is the strongest predictor of clinical outcome, used for staging
        • Measure vertically from the top of granular layer of the epidermis to the deepest invasive melanoma cell(s)
        • If ulcerated, measure from base of ulcer
        • Round to nearest 0.1 mm using ocular micrometer
        • Avoid measuring vascular invasion, microsatellites, involvement of skin appendages
  • Melanoma arising in congenital nevi (Am J Dermatopathol 2013;35:e16)
    • Dermal lesions composed of epithelioid cells, spindle cells or round cells resembling a malignant small round blue cell tumor
    • Proliferative nodules may be present
    • Generally, little to no necrosis, cytological atypia or increased mitotic activity
  • Spitz and spitzoid melanoma (Pediatr Blood Cancer 2018;65:10.1002/pbc.26792, Diagnostics (Basel) 2023;13:2380)
    • Presence of enlarged epithelioid or spindled cells
    • Dome shaped configuration with epidermal hyperplasia
    • Vertical disposition of melanocytes
    • Asymmetry, absence of dermal maturation
    • May reach Breslow > 10 mm without ulceration
    • Frequent mitoses in the dermis
    • High grade of cellular atypia
    • High N:C ratio
    • Absence of Kamino bodies
Microscopic (histologic) images

Contributed by Idy Tam, M.D. and Bethany R. Rohr, M.D.
Poorly circumscribed proliferation

Poorly circumscribed proliferation

Pagetoid melanocytes

Pagetoid melanocytes

Pleomorphic melanocytes

Pleomorphic melanocytes

PRAME immunostain

PRAME immunostain

SOX10 immunostain

SOX10 immunostain

Molecular / cytogenetics description
  • Fluorescence in situ hybridization (FISH) to identify copy number alterations of chromosomes in melanoma and Spitz tumors (Am J Surg Pathol 2013;37:676)
    • Interpret in context with clinical and histopathologic findings
      • 6p25
      • 6q23
      • 11q13
      • 9p21
      • 8q24
  • Next generation sequencing to identify melanoma related gene mutations (Am J Pathol 2002;161:1163)
    • Interpret in context with clinical and histopathologic findings
      • BRAF
      • TERT
      • MAP3K8
      • RET
      • ALK
      • NTRK
      • ROS1
  • Comparative genomic hybridization can detect amplifications and deletions of smaller DNA regions along the chromosome (Am J Pathol 2002;161:1163, Pathology 2004;36:458)
    • Can detect copy number variations of melanomas arising in giant congenital nevi
    • Melanomas show frequent aberrations in chromosomes 6, 7, 9 and 10
Molecular / cytogenetics images

Images hosted on other servers:
Abnormal FISH with (6p25; red) gain; (6q23, yellow) loss

Abnormal FISH with (6p25; red) gain; (6q23, yellow) loss

Sample pathology report
  • Skin, biopsy:
    • Invasive malignant melanoma, superficial spreading subtype (Breslow depth to the nearest 0.1 mm) (see comment)
    • Comment: The sections demonstrate a highly atypical compound melanocytic proliferation consisting of irregular epithelioid melanocytes. These melanocytes exhibit poor nesting along the dermal epidermal junction, showing both confluence and pagetoid scatter. In the dermis, melanocytes fail to mature and disperse with descent. Dermal mitotic activity is observed.
Differential diagnosis
  • Benign nevi:
    • Well circumscribed and symmetric
    • Well nested junctional component without significant pagetoid scatter or confluence
    • Dermal component matures and disperses with descent
  • Dysplastic nevi:
    • Can resemble melanoma clinically with asymmetry, border irregularity, color variegation and large diameters
    • Generally, lacks severe cytologic and architectural atypia
    • Dermal component matures and disperses with descent
    • Lacks dermal cytologic atypia, pleomorphism and mitotic activity
    • Histologically may resemble early melanoma, especially in severely dysplastic nevi
  • Spitz nevi:
    • Often presents as pink papules that primarily affect pediatric patients
    • Histologically lacks severe cytologic atypia and has rare mitotic figures
      • Should be well demarcated
      • Usually lacks deep dermal to subcutaneous extension
      • Presence of Kamino bodies
  • Blue nevi:
    • Blue to dark gray homogenous macules or papules
    • Histologically lacks cytologic atypia and mitotic figures
    • Sclerotic stroma
    • Various subtypes
  • Pyogenic granulomas:
    • Red, friable, bleeding papule
    • May clinically resemble Spitz or spitzoid melanoma and amelanotic melanoma
    • Histologically, this is a vascular tumor with lobular thin capillaries with surrounding fibrous stroma
  • Deep penetrating nevus:
    • Dark dome shaped papule
    • Histologically, it is wedged shaped or plexiform growth pattern with melanin pigment
    • Well circumscribed and symmetrical
    • Can have occasional mitotic figure and cytologic atypia
Board review style question #1
Pleomorphic melanocytes


A 7 year old child presents with a new, evolving, reddish, dome shaped papule that is symmetric with regular borders. What are the ABCD criteria of childhood melanoma?

  1. Amelanotic, bleeding / bump, color uniformity, de novo / any diameter
  2. Amelanotic, bleeding / bump, color variegation, diameter > 6 mm
  3. Asymmetry, bleeding / bump, color uniformity, diameter > 6 mm, evolution over time
  4. Asymmetry, irregular borders, color variegation, diameter > 6 mm, evolution over time
Board review style answer #1
A. Amelanotic, bleeding / bump, color uniformity, de novo / any diameter. Childhood melanomas often do not adhere to the conventional ABCDE criteria because often spitzoid melanomas occur. The deviation from the typical criteria includes lesions that are amelanotic, symmetric, pigmented or bleeding with color uniformity. Answers B - D are incorrect because these lesions tend to be de novo and can be of any size. In addition, the evolution of lesions over time is not a good indicator for pediatric melanoma because at this age group, new onset and evolution of common nevi is expected.

Comment Here

Reference: Pediatric melanoma
Board review style question #2
What is the recommended method for biopsy when there is clinical suspicion of melanoma in a child?

  1. Excisional biopsy of entire lesion
  2. Incisional biopsy of thickest portion of the lesion
  3. Punch biopsy of thickest portion of the lesion
  4. Superficial shave biopsy of the entire lesion
Board review style answer #2
A. Excisional biopsy of entire lesion. Excision biopsy is the preferred approach for suspected malignant melanoma. Answer B is incorrect because incision biopsy can be considered for large lesions in areas where cosmetic concerns are heightened, such as on the face or in cases of acral melanoma. In certain instances, incision biopsy may also be justified in regions undergoing recent changes within a giant congenital nevus. However, partial sampling of the lesion will be inadequate for accurate staging. Answers C and D are incorrect because other biopsy methods, including punch and superficial shave techniques, are not recommended as they lack the ability to provide comprehensive histological staging. At times, deeper scoop shave biopsies may be utilized to accurately sample melanoma and determine the lesion's true depth.

Comment Here

Reference: Pediatric melanoma
Board review style question #3
What is the role of fluorescence in situ hybridization (FISH) in the molecular characterization of pediatric melanoma?

  1. Analysis of TERT promoter alterations
  2. Assessment of chromosomal copy number variations
  3. Detection of BRAF mutations
  4. Sequencing of melanoma specific gene panels
Board review style answer #3
B. Assessment of chromosomal copy number variations. FISH is used to identify copy number variations of chromosomes in melanoma and spitz tumors. Answers A, C and D are incorrect because they do not support the purpose of FISH.

Comment Here

Reference: Pediatric melanoma
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