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Melanoma variantDiagnostic pitfallICD-10 C43.x

Amelanotic & hypopigmented melanoma

Amelanotic melanoma · hypopigmented melanoma · pink melanoma

Amelanotic melanoma is melanoma that lacks visible pigment clinically; hypopigmented melanoma has minimal pigment. Together they account for 2-8% of cutaneous melanomas — and a disproportionately high share of delayed-diagnosis cases. Clinical morphology is pink, red, skin-coloured, or tan with subtle borders. Common at acral / nail / mucosal sites, in elderly patients, and in association with desmoplastic melanoma. Pattern recognition relies on dermoscopic vascular and asymmetry features rather than pigment cues.

CurrentLast reviewed 16 May 2026
Clinical image of Amelanotic & hypopigmented melanoma
Amelanotic & hypopigmented melanoma. Image sourced from DermNet New Zealand. Used under CC BY-NC-ND 4.0. No endorsement implied.

Epidemiology

  • 2-8% of cutaneous melanomas; under-diagnosed (estimates rise with awareness).
  • Older adults; fair-skinned phenotype; red hair / MC1R variants.
  • Disproportionately:
    • Acral / nail / mucosal melanomas.
    • Desmoplastic melanoma.
    • Spitzoid melanoma.
    • Local recurrences after WLE.
  • Frequently misdiagnosed as pyogenic granuloma, BCC, dermatofibroma, eczematous patch, scar, infection.

Clinical features

  • Pink, red, skin-coloured or tan; variable subtle pigment specks.
  • Common appearances:
    • Pink papule / nodule (often bleeding / ulcerated).
    • Hypopigmented plaque on chronically sun-damaged skin.
    • Pink "scaly" macule mimicking AK / Bowen.
    • Skin-coloured indurated plaque (desmoplastic variant).
  • Growth: usually rapid; out of proportion to apparent "size".
  • EFG rule (for nodular amelanotic):
    • Elevated.
    • Firm.
    • Growing for >1 month.

Dermoscopy clues

  • Polymorphous vessels (linear, dotted, hairpin, glomerular together).
  • Milky-red areas / globules.
  • Crystalline / shiny white structures.
  • Asymmetric structure within lesion despite minimal pigment.
  • Residual pigment specks / blue-grey dots at periphery.
  • Predictors of amelanotic melanoma on dermoscopy (Menzies): milky-red areas + polymorphic vessels + asymmetric distribution.
  • Useful to compare with patient's other lesions — "ugly duckling".

Differentials

  • Pyogenic granuloma — abrupt history, easy bleeding; collarette of scale; but excisional biopsy mandatory to exclude amelanotic melanoma.
  • BCC — pearly, arborising vessels.
  • Dermatofibroma — chronic firm papule; dimple sign; central white scar-like patch.
  • Spitz naevus — paediatric / young adult; pink dome; dermoscopy globules.
  • Eccrine poroma.
  • Kaposi sarcoma nodule.
  • Atypical fibroxanthoma / pleomorphic dermal sarcoma.
  • Cutaneous metastasis.
  • Pink / red Spitzoid melanoma.

Investigations

  • Excisional biopsy mandatory for any rapidly-growing pink papule / nodule in an adult.
  • Dermoscopy as adjunct (not substitute for biopsy).
  • Histology: atypical melanocyte proliferation, sometimes with sparse pigment; can resemble carcinoma, sarcoma, lymphoma.
  • IHC mandatory:
    • S100 (sensitive but non-specific).
    • SOX10 (sensitive).
    • Melan-A / MART-1 (less sensitive in desmoplastic).
    • HMB-45 (less sensitive).
    • MITF.
    • PRAME.
  • BRAF V600 / NRAS for stage III+ disease.
  • Pitfall: desmoplastic melanoma may be Melan-A / HMB-45 negative — use S100 / SOX10 broad panel.

Management

  • Same AJCC 8 staging and NICE NG14 management as conventional melanoma.
  • Higher prevalence of advanced stage at diagnosis owing to delay — careful counselling and prompt referral.
  • SLNB per standard criteria.
  • Adjuvant therapy and surveillance per stage.
  • Multidisciplinary team discussion essential given diagnostic uncertainty.
  • Counsel:
    • Recurrence may also present amelanotic.
    • Self-skin examination education (EFG rule); lower threshold for re-presentation.

References

  1. Menzies SW et al. Dermoscopic features of amelanotic and hypomelanotic melanoma. Arch Dermatol. 2008;144:1120-1127.
  2. Chamberlain AJ et al. The role of dermatoscopy in amelanotic / hypomelanotic melanoma. Br J Dermatol. 2003;149:826-829.
  3. Detrixhe A et al. Melanoma masquerading as nonmelanocytic lesions. Melanoma Res. 2016;26:631-634.
  4. NICE NG14. Melanoma: assessment and management. London: NICE; 2015 (last updated 27 July 2022).
  5. Kelly JW et al. Nodular melanoma: no longer as simple as ABC. Aust Fam Physician. 2003;32:706-709.

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