Childhood Melanoma: Causes, Signs, Diagnosis, And Care

Childhood melanoma is an exceptionally rare form of skin cancer that occurs in patients under the age of 18, accounting for less than 3% of all childhood malignancies. Despite its rarity, it poses significant challenges due to delayed diagnosis stemming from low clinical suspicion and atypical presentations that mimic benign conditions. This article comprehensively reviews the epidemiology, risk factors, clinical and pathological features, diagnostic approaches, management strategies, prognosis, and prevention of melanoma in children and adolescents.

What is Childhood Melanoma?

Melanoma arises from malignant transformation of melanocytes, the pigment-producing cells in the skin. In children, it is classified into two main categories: conventional melanoma, which resembles adult forms, and melanoma arising in congenital melanocytic naevi. The former predominates in adolescents, while the latter is more common in younger children. Unlike adults, childhood melanoma often presents with thicker tumours at diagnosis, leading to advanced stages and potentially worse outcomes if not addressed promptly.

Incidence rates are extremely low, estimated at 0.4–2.5 cases per million children under 18 years annually. Diagnosis is rare before puberty, with most cases occurring in adolescents aged 12–18 years. No significant gender disparity exists in prepubertal children, though postpubertal incidence may rise slightly in females.

Who Gets Childhood Melanoma?

Childhood melanoma affects individuals under 18 years, with distinct epidemiological patterns:

• Prepubertal children (<11 years): Extremely rare (<1% of melanomas); often linked to giant congenital naevi or genetic syndromes.
• Adolescents (11–18 years): Comprise 73–90% of cases; presentations similar to adults but with diagnostic delays.
• Geographic variation: Higher in sun-exposed regions like Australia (median age 10 years in Australasian studies).

Risk increases with fair skin, numerous naevi, and family history. A study of 317 patients found 73% were adolescents, with 11% arising from congenital naevi.

Causes and Risk Factors

The aetiology mirrors adult melanoma but with unique paediatric aspects:

Genetic Factors

Predisposition syndromes include:

• Familial atypical multiple mole melanoma (FAMMM) syndrome: CDK4, CDKN2A mutations.
• Xeroderma pigmentosum (XP): DNA repair defects; markedly elevated risk.
• Li-Fraumeni syndrome: TP53 mutations.
• MC1R variants implicated in some cohorts.

Precursor Lesions

• Giant congenital melanocytic naevi (>20 cm adult size): Lifetime risk of melanoma ~6–10%, often neurotized or visceral.
• Multiple dysplastic naevi or high naevus count (>50).

Environmental Factors

UV exposure, sunburns (especially <5 years), tanning beds, and immunosuppression (e.g., post-transplant). Children with melanoma have more naevi than those with Spitz tumours.

Clinical Features

Paediatric melanomas often evade standard ABCDE criteria (Asymmetry, Border irregularity, Colour variation, Diameter >6mm, Evolving). Instead, use modified paedABCD:

• A: Amelanotic.
• B: Bleed/Bump (raised, nodular).
• C: Colour uniformity.
• DE: De novo, any Diameter/Evolving.

Common features:

• Amelanotic or uniformly coloured nodules.
• Locations: Extremities (35% lower limbs), trunk, head/neck.
• Symptoms: Bleeding, rapid growth, ulceration.
• Subtypes: Spitzoid (31%), superficial spreading (26%), nodular.

Diagnosis

Diagnosis requires high suspicion, biopsy, and expert pathology review. Delays average 13 months due to misdiagnosis as warts, granulomas, or trauma.

Histopathology

Features include ulceration, lack of maturation, mitoses, pagetoid spread, atypia. Mitotic rate > tumor thickness predicts recurrence.

Ancillary Tests

• Immunohistochemistry: S100, HMB45, Melan-A.
• FISH/CGH: Detects chromosomal abnormalities.
• Sentinel lymph node biopsy (SLNB): Positive in 46%.

Staging: AJCC adapted for paediatrics; thicker tumours common.

Management and Treatment

Treatment follows adult guidelines with paediatric adaptations:

1. Wide local excision: Margins 1–2 cm based on thickness.
2. SLNB: For intermediate/high-risk; guides completion lymphadenectomy.
3. Adjuvant therapy: Immunotherapy (anti-PD1), targeted (BRAF inhibitors) for stage III/IV.
4. Chemotherapy/Radiotherapy: Limited role; reserved for advanced disease.

In a 35-year BC study, 85% survival with surgery alone; fatalities linked to chemo/radio.

Prognosis

Overall survival 70–90%, better than adults for equivalent stage but worse due to thickness. Favourable factors: Adolescents, superficial spreading type. Poor: Nodular, young age (<10 years), nodal involvement. Spitzoid: High nodal risk, low mortality.

Prevention

Primary prevention mirrors adults:

• Sun protection: SPF50+ sunscreen, clothing, shade (<10am/4pm).
• Avoid tanning beds (<18 banned in many regions).
• Monitor high-risk children: Regular skin exams for congenital naevi, dysplastic syndromes.
• Education: Teach parents paedABCD criteria.

Frequently Asked Questions (FAQs)

Q: How common is melanoma in children?

A: Very rare, <3% of childhood cancers, ~2 per million under 18 years.

Q: Does it look like adult melanoma?

A: No, often amelanotic, nodular, bleeding; use paedABCD instead of ABCDE.

Q: Is it curable if caught early?

A: Yes, 85–90% survival with prompt surgery; delays worsen prognosis.

Q: Should I biopsy every unusual spot on my child?

A: Consult dermatologist for suspicious lesions: rapid change, bleeding, irregular.

Q: Can sun exposure cause it in kids?

A: Yes, sunburns double risk; rigorous protection essential.

Sneha Tete

Health Writer