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BenignLM DDxICD-10 L81.4

Ink-spot lentigo

reticulated black solar lentigo · reticulated lentigo · solar reticulated lentigo · ink-spot reticulated lentigo

Ink-spot lentigo is a benign solar lentigo variant with a characteristic dramatically dark, jagged, reticulated pattern that mimics melanoma in situ — particularly lentigo maligna — on chronically sun-damaged skin of older fair-skinned adults. Despite its alarming appearance, dermoscopy shows a sharply circumscribed, irregular, dark pigment network without melanoma-specific features. Recognition is essential to avoid unnecessary excision, while ensuring true LM is not missed.

CurrentLast reviewed 16 May 2026
Clinical image of Ink-spot lentigo
Ink-spot lentigo. Image sourced from DermNet New Zealand. Used under CC BY-NC-ND 4.0. No endorsement implied.

Clinical features

  • Single or few sharply demarcated dark brown / black macules.
  • Irregular, jagged, "ink-blot"-like outline.
  • 1-5 mm diameter typically; can be larger.
  • Sites: shoulders, upper back, dorsal forearms — chronically sun-damaged skin.
  • Older adults; fair Fitzpatrick I-II skin; high lifetime UV exposure.
  • Stable; slow growth at most.
  • Often co-exists with conventional solar lentigines.

Dermoscopy

  • Sharply circumscribed dark pigment network — the hallmark.
  • Network composed of regular thick interconnecting lines and small holes.
  • Symmetric structure within the irregular outline.
  • No melanoma features:
    • No atypical pigment network.
    • No blue-white veil.
    • No regression / shiny white structures.
    • No pseudopods, streaks, or atypical globules.
    • No asymmetric pigmented follicular openings (LM features).
  • Sometimes "fingerprint" pattern reminiscent of solar lentigo.

Differentials

  • Lentigo maligna — pseudo-network with asymmetric pigmented follicular openings; rhomboidal structures; slate-grey dots; biopsy if uncertain.
  • Pigmented actinic keratosis — keratotic scale; pseudo-network.
  • Solar lentigo (typical) — moth-eaten edge; uniform light tan pigment.
  • Atypical naevus / dysplastic naevus.
  • Pigmented BCC — pearly border, blue-grey ovoid nests, arborising vessels.
  • Naevoid melanoma — biopsy if any atypia.
  • Pigmented seborrhoeic keratosis — milia-like cysts.

Management

  • Reassurance — benign solar lentigo variant.
  • If diagnostic uncertainty at dermoscopy / clinical examination → excisional biopsy (preferred to shave / punch) to exclude lentigo maligna.
  • Cosmetic management:
    • Q-switched / picosecond laser for pigment.
    • Cryotherapy (caution about hypopigmentation in Fitzpatrick III-VI).
    • Tretinoin / hydroquinone (modest).
  • Counsel about photoprotection given background of chronic UV damage.
  • Document with photography; surveillance if multiple atypical-pigmented lesions on background of solar damage.
  • Consider field-cancerisation assessment — look for actinic keratoses, Bowen disease, BCC.

References

  1. Bolognia JL. Reticulated black solar lentigo ("ink spot" lentigo). Arch Dermatol. 1992;128:934-940.
  2. Carrera C et al. Dermoscopy of facial lentigines: ink-spot lentigo / reticulated lentigo. Br J Dermatol. 2018;179:1199-1200.
  3. Stolz W, Argenziano G. Dermoscopy of pigmented skin lesions. Atlas of Dermoscopy; 2002.
  4. British Association of Dermatologists. Lentigines — patient information leaflet. London: BAD; 2023.

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