Table of Contents
Lichen planus – low magnification
- Irregular acanthosis
- Hyperkeratosis
Acanthosis is characterized by thickening of the entire epidermis, with a predominance of thickening in the spinous layer.
Hyperkeratosis refers to an increased thickness of the stratum corneum.
Lichen planus
The epidermis shows sawtooth-shaped acanthosis.
Band-like Lymphocytic Infiltrate at the Dermoepidermal Junction
Interface Dermatitis (Lymphocytes appear to “nibble” at the epidermal basement membrane, a hallmark of interface dermatitis).
Lichen planus
- Compact orthokeratotic hyperkeratosis
Hyperkeratosis may be parakeratotic (with retained nuclei in keratinocytes) or orthokeratotic (without retained nuclei). In lichen planus, the hyperkeratosis is compact and orthokeratotic.
Lichen planus
LEGEND
A dense band-like lichenoid lymphocytic infiltrate is noted in the papillary dermis.
Lichen planus
LEGEND
Triangular hypergranulosis: focally thickened granular layer of the epidermis with a wedge-shaped (triangular) appearance.
- This wedge-shaped hypergranulosis is responsible for the clinical finding of Wickham striae.
Lichen planus
LEGEND
Civatte Bodies (Apoptotic Keratinocytes): pink-stained apoptotic keratinocytes seen at the dermoepidermal junction, also called Civatte bodies.
Lichen planus
LEGEND
Band-like lymphocytic infiltrate
Interface dermatitis
Hyperkeratosis
Focal hypergranulosis
Squamatization of the basal membrane
Civatte bodies
Irregular sawtooth acanthosis (epidermal ridges ending in points)
Lichen planus
LEGEND
Hypergranulosis
These vacuoles, when numerous, can lead to the formation of a true blister (also known as bullous lichen planus).
Interface dermatitis: the lymphocytes appear to nibble at the basement membrane, leading to the formation of vacuoles (even visible at low magnification).
Lichen planus
LEGEND
Squamatization of the Basal Membrane: basal keratinocytes, typically cuboidal or rectangular, appear flattened and elongated, resembling upper spinous layer keratinocytes. This is referred to as “squamatization.”
Lichen planus
LEGEND
Unlike certain interface dermatitides (for example, erythema multiforme and fixed pigmented erythema), apoptotic keratinocytes are often limited to the lower layer of the epidermis.
Civatte bodies (apoptotic keratinocytes)
Hypertrophic lichen planus – low magnification
LEGEND
Severe hyperkeratosis with irregular sawtooth acanthosis
Focal hypergranulosis
Lichenoid interface dermatitis with a band-like lymphocytic infiltrate
Hypertrophic lichen planus – high magnification
LEGEND
Squamatization of basement membrane
Interface dermatitis with band-like lymphocytic infiltrate; exocytosis of lymphocytes into the epidermis and some apoptotic keratinocytes
