Introduction

Keratosis lichenoides chronica (KLC) presents clinically with violaceous, papular and nodular lesions in a linear or reticulate pattern.

Histology of keratosis lichenoides chronica

Histologically, keratosis lichenoides chronica is characterised by a lichenoid reaction pattern with marked basal cell death and vacuolar degeneration (figures 1-3). The dermal infiltrate shows a mixture of cells which may include plasma cells. The epidermal changes are highly variable — acanthosis, parakeratosis, and atrophy are all described features. Cornoid lamellae and eccrine infiltrates have been described.

Keratosis lichenoides chronica figure 1

Keratosis lichenoides chronica figure 2

Keratosis lichenoides chronica figure 3

Special stains for keratosis lichenoides chronica

None are generally needed. PAS stain may be useful to exclude a superficial fungal infection.

Differential diagnosis of keratosis lichenoides chronica

Diagnosis is difficult without clinical correlation. Some authors feel this is likely an unusual chronic form of lichen planus.

Pityriasis lichenoides can show a similar pathology but has a distinct clinical presentation.