Lichen planus is a chronic inflammatory disease that affects the skin and mucous membranes. Microscopically, it is characterized by a band-like lymphohistiocytic infiltrate at the dermo-epidermal junction, vacuolar alteration of basal keratinocytes, saw-toothed rete ridges, and wedge-shaped hypergranulosis. Clinically, it presents as pruritic, violaceous flat-topped papules and plaques, often with white Wickham striae. Variants include hypertrophic, atrophic, ulcerative, actinicus, and lichen planopilaris forms. It is important to differentiate lichen planus from other lichenoid

1. B Y : - D R P U S H K A R C H A U D H A R Y
S S S M C R I 2 N D Y E A R P G M D P A T H O L O G Y
G U I D E D B Y : P R O F N A S E E M N O O R U N N I S A
P R O F A N D H O D D E P T O F P A T H O L O G Y
S S S M C & R I
LICHEN PLANUS

2. OVERVIEW
 SKIN NORMAL HISTOLOGY
 MICROSCOPIC TERMINOLOGY
 LICHEN PLANUS DEFINITION
 PATHOGENESIS
 MORPHOLOGY
 VARIANTS
 DIFFERENTIAL DIAGNOSIS

3. SKIN NORMAL HISTOLOGY

6. MICROSCOPIC TERMINOLOGY
 Acanthosis- Diffuse epidermal hyperplasia
 Hyperkeratosis -Thickening of the stratum
corneum, often associated with a qualitative
abnormality of the keratin
 Parakeratosis - Keratinization with retained
nuclei in the stratum corneum
 Orthokeratosis is Hyperkeratosis without
parakeratosis

7.  Hypergranulosis- Hyperplasia of the stratum
granulosum, often due to intense rubbing
 Vacuolization- Formation of vacuoles within or
adjacent to cells; often refers to basal cell-
basement membrane zone (BMZ) area .
 Spongiosis- Intercellular edema of the
epidermis

8. DEFINITION
 Lichen planus is a subacute or chronic dermatosis
that may involve skin, mucous membranes, hair
follicles, and nails .

11. PATHOGENESIS
 The pathogenesis of lichen planus is not known.
 It is plausible that expression of altered antigens
in basal epidermal cells elicit a cell-mediated
cytotoxic (CD8+) T cell response.
 T-lymphocyte infltrates and Macrophages are
characteristic features of this disorder.

13. MORPHOLOGY
 Cutaneous lesions consist of itchy,
violaceous, flat-topped papules that may
coalesce focally to form plaques.
 These papules are often highlighted by
white dots or lines called Wickham striae,
which are created by areas of
hypergranulosis.

14. MORPHOLOGY
 Lesions are usually multiple and
symmetrically distributed, particularly on
the extremities and often about the wrists
and elbows.
 The glans penis is another common site
of involvement.

15. Histopathology
LAYER FINDINGS
STRATUM
CORNEUM
1. Hyperkeratosis w/o parakeratosis
2. Oral LP  parakeratosis rather than hyperkeratosis
STRATUM
GRANULOSUM
• Focal wedge shaped hypergranulosis
STRATUM
SPINOSUM
1. Irregular acanthosis with saw-toothed rete ridges
2. Intercellular edema
STRATUM
BASALE
1. Vacuolar alteration )Liquefaction degeneration( of the basal
cells
2. Colloid (Civatte, hyaline or cytoid) bodies
3. Max Joseph spaces (Clefts between the epidermis & dermis)
PAPILLARY
DERMIS
1. Lichenoid lymphohistiocytic infiltrate  dense, band-like
infiltrate (interface dermatitis)
2. Colloid (Civatte) bodies
3. Melanin incontinence  Melanophages
4. LPP  lymphohistiocytic infiltrate around hair follicle

23. VARIANTS
 Hypertrophic lichen planus
 Atrophic lichen planus
 Ulcerative (erosive) lichen planus
 Lichen planus actinicus
 Lichen planopilaris (LPP)


24. Hypertrophic lichen planus

27. Atrophic lichen planus

28. Ulcerative lichen planus
 Epidermal ulceration with lichen planus at margins.

31. Lichen planus actinicus
 Resembles lichen planus but more melanin
incontinence; focal parakeratosis

33. Lichen planopilaris

37. DIFFERENTIAL DIAGNOSIS
 Lichen planus like keratosis
 Lichen nitidus
 Lichenoid drug eruptions
 Lichen striatus
 Discoid lupus erythmatosus

38. LICHEN PLANUS LIKE KERATOSIS
 LP+PARAKERATOSIS(MORE
COMMON)+EOSINOPHILS AND PLASMA CELLS
IN THE INFILTRATE(MORE COMMON)

42. LICHEN NITIDUS

47. BALL IN CLAW APPEARANCE

53. LICHEN STRIATUS

57. DISCOID LUPUS ERYTHMATOSUS