Path Quiz Case-96: Diagnosis- Lichen Planus

            Dr  Sampurna Roy  MD

           Path Case 96: Case history and images:

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 Lichen Planus: Image

Microscopic features:  Orthokeratoic hyperkeratosis, wedge shaped hypergranulosis and saw- tooth appearance of the epidermis; Image
Effacement of the dermoepidermal junction by band-like mononuclear inflammatory cell infiltrate ;                 
Hydropic degeneration of basal cells ; Colloid body formation ;   Pigment incontinence; Image

Variants of Lichen Planus:       

Atrophic Lichen Planus:    Loss of normal rete ridges. Inflammatory infiltrate less dense.
Hypertrophic Lichen Planus:  ImageEpidermal hyperplasia with changes limited to the tips of the rete-ridges. Often superadded lichen simplex chronicus.
Ulcerative Lichen planus:   Common sites include feet, perineum, vulva,vagina & mouth. Changes present at the edge of the ulcer. Plasma cells are present in the mucosal lesions.
Erythema dyschromicum perstans:    Macular variant of lichen planus. Prominent melanin incontinence.
Lichen planus actinicus:   Usually in young individuals of Oriental origin. Prominent melanin incontinence.
Lichen planus pemphigoides:   Cell poor subepidermal bulla.
Lichen planopilaris: Diagram  Infiltrate extends around hair follicle.

Lichen Nitidus: ;  Path Case76  ;  Diagram

Lichenoid keratosis (lichen planus-like keratosis): Image

Presents as solitary lesion on sun-exposed skin. Site: Usually located on the upper limbs.
Microscopic features: Histopathological features mimic lichen planus. Prominent Civatte body formation. Serial sectioning reveals solar lentigo at the margins. Focal parakeratosis. (+). Hypergranulosis not as prominent as in lichen planus.

Lichenoid drug eruption:

Microscopic features: Focal parakeratosis, spongiosis and mild basal cell degeneration. Some eosinophils and plasma cells in the dermal infiltrate. Inflammatory  infiltrate extends around blood vessels in the mid and deep dermis.
Sometimes drug eruptions may present with a hypertrophic lichen planus- like picture. Rarely multinucleated giant cells are present known as ' giant cell lichenoid dermatitis

Fixed drug eruption: Image

Microscopic features: Lichenoid reaction pattern, hydropic degeneration and presence of necrotic keratinocytes in the basal layer & higher up in the epidermis. Prominent melanin incontinence is present. Inflammatory infiltrate obscure the dermoepidermal junction. Extends upto mid or upper epidermis.

Lichenoid graft versus host disease:  Image

Clinical history is important.
Microscopic features: Inflammatory cellular infiltrate is not band-like and is less prominent than in lichen planus. 
Necrotic keratinocytes present at all levels of epidermis , accompanied by lymphocytes (satellite cell necrosis).

Lichen Striatus:  Diagram

Microscopic features: Features may mimic lichen planus. However, interphase changes are focal (occupy three or four adjacent dermal papillae). There is  focal spongiosis. Deep perieccrine  inflammatory infiltrate is present.

Other lesions showing lichen planus- like (lichenoid) reaction:

Lichenoid  reaction to tumour  following regression of melanocytic or epithelial tumours. In a tatoo there are macrophages containing tatoo pigments.

Discoid lupus erythematosus: Image             

Well demarcated erythematous scaly patches. Site:  Face, cheek, bridge of nose, sometimes neck, scalp, lips, oral mucosa.
Microscopic features:  Hyperkeratosis and follicular plugging. Atrophy of epidermis. Lichenoid reaction pattern characterized by vacuolar degeneration & presence of Civatte bodies.  Thickening of the basal membrane. 
Superficial and deep perivascular and periadnexal inflammatory infiltrate. Image