Instructor: Dr. Heddie Sedano
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LICHEN PLANUS: LECTURE (p. 5)
The skin lesions of LP are maculo-papular with a bluish-silver color and generally are
accompanied by pruritus. The most frequently affected areas are the skin of the forearm,
anterior leg and genitalia, especially the scrotum and the labia majora. During the early
stages they are covered with a whitish keratinacious film. Because these lesions are markedly
pruritic the patient tends to scratch them constantly producing linear extensions of the lesions.
With time these areas become pigmented with melanin, the pigmentation remains after resolution
of the cutaneous LP lesions. The marked pruritus may be associated to the increased number of
mast cells in LP lesions. Mast cells produce histamine which is considered responsible for
pruritus.
FIG10. Cutaneous LP note in the left photo (forearm) the bluish hue of these
lesions as well as open ulcers produced by the patient while scratching these
extremely pruritic lesions. The right photo is a close-up view of an early LP lesion in the skin of the leg.
 FIG11. Routine hematoxylin-eosin stain of a reticular LP lesion of the oral mucosa. Note the band-like lymphocytic infiltrate in the connective tissue immediately below the epithelium. Some lymphocytes are also in an intraepithelial location. |
Histologically LP presents different images in accordance to its cinical variety, one common feature is the presence of a band-like lymphocytic infiltrate present in the connective tissue subjacent to the affected epithelium. The reticular variety will present a thickened ortho- or parakeratin layer especially at the areas of the Wickham's striae. The spinous cell layer will be increased in size (acanthotic) and lymphocytes will be seen in the suprabasilar epithelial layers. The erosive variety will show areas where the epithelium is markedly thin or even absent exposing the connective tissue to the oral cavity. Subepithelial splitting can also be seen in advanced cases of the erosive variety. Immunofluorescent studies show a positive reaction for fibrinogen at the level of the basal membrane and are negative for IgA, IgG and IgM antibodies. |
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