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Lichenoid keratosis
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Lichenoid keratosis

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Contributors: Erik Domingues MD, Belinda Tan MD, PhD, Sarah Hocker DO, Nikki Levin MD
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Synopsis

Lichenoid keratosis, or benign lichenoid keratosis (BLK), solitary lichenoid keratosis (SLK), lichen planus-like keratosis (LPLK), solitary lichen planus, or involuting lichenoid plaque, is an asymptomatic or mildly pruritic pink papule or plaque commonly found on sun-exposed areas, usually the upper chest and forearms and less often the head and neck. Clinically, it may simulate an actinic keratosis, basal cell carcinoma (eg, nodular or superficial), squamous cell carcinoma in situ, or seborrheic keratosis, whereas histologically it is almost identical to lichen planus.

Lichenoid keratoses typically develop in patients of Northern European descent aged 30-70. Women are affected 3 times as often as men.

The pathogenesis of lichenoid keratosis is not entirely understood, but it is thought to represent an inflammatory reaction occurring in a preexisting solar lentigo, seborrheic keratosis, or actinic keratosis.

Lichenoid keratoses are usually asymptomatic but may be slightly pruritic. Patients occasionally report that the lesion has changed, prompting examination of the lesion and biopsy. On average, the lesion has been present for 6 months at the time of diagnosis.

Most lichenoid keratoses are erythematous / pink, although some are violaceous or hyperpigmented. They are typically solitary and range in size from 3-19 mm in diameter. They may be scaly, pearly, or indurated.

Lichenoid keratoses often involute spontaneously over a period of months.

Codes

ICD10CM:
L43.9 – Lichen planus, unspecified

SNOMEDCT:
403198004 – Lichenoid keratosis

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

  • Lichen planus – Presents with multiple pruritic, polygonal purple plaques, whereas lesions of lichenoid keratosis are usually solitary. Look for Wickham striae and oral white lacy reticulate plaques on buccal mucosa (see oral lichen planus).
  • Basal cell carcinoma – Nodular subtype presents with a solitary shiny, red nodule with large telangiectatic vessels that may show ulceration or bleeding; superficial subtype presents with flat, well-demarcated erythematous plaques resembling eczema but unresponsive to eczema therapies. Biopsy is diagnostic.
  • Squamous cell carcinoma – A verrucous, scaly, often crusted papule or plaque. Biopsy is diagnostic.
  • Seborrheic keratosis – A hyperpigmented "stuck-on"-appearing plaque with horn cysts not confined to arms, chest, head, and neck; usually multiple. Biopsy will show pseudohorn cysts.
  • Nevus – A flesh-colored to hyperpigmented macule or papule that is usually not scaly. Biopsy is diagnostic.
  • Melanoma – Usually presents with irregularities in pigmentation, colors, borders, and symmetry. Biopsy is diagnostic.

Best Tests

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Therapy

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References

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Last Updated: 11/15/2018
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Lichenoid keratosis
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Lichenoid keratosis : Erythema, Scaly papule
Clinical image of Lichenoid keratosis
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