Also known as: lichen planus-like keratosis, solitary lichen planus

Clinical Features:

• Most common in middle aged white individuals, with a female predominance
• Usually of short duration
• Most often presents as a solitary, sharply demarcated papule or plaque, with a predilection, for the face, neck, upper trunk and distal upper extremity
• Often misdiagnosed clinically as a seborrheic wart, superficial BCC or acitinic keratosis

Histologic Features:

• The findings are quite similar to those of lichen planus:
  • Hyperkeratosis, often with focal parakeratosis
  • Hypergranulosis
  • Variable acanthosis
  • Basal cell vacuolar change
  • Often exocytosis of lymphocytes
  • Epidermal and dermal colloid bodies
  • Pigment incontinence
• The saw-tooth rete ridge pattern typically of lichen planus is sometimes seen, but lichenoid keratosis more frequently shows broadened, irregular rete ridges.
• There is most often a dense lichenoid lymphohistiocytic infiltrate, as in lichen planus; however, occasionally the infiltrate in lichenoid keratosis is mainly perivascular.  Focal plasma cells and eosinophils may also be present.
• The basal layer may show reactive atypia.
• Immunofluorescence shows staining for IgM and sometimes IgG, as in lichen planus.

Cases associated with this book:

Lichenoid keratosis
Author: Stephen Lyle, M.D., Ph.D.

Conference: DermatopathologyConsultations.com Teaching Collection