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Lichenoid Reactions (LE)

 

 LUPUS ERYTHEMATOSUS FIGURES RELATED TO THE DISCUSSION

 

 OF THE LICHENOID REACTION IN THE COLLAGEN-VASCULAR DISEASES


 

Fig. 1:  The lesion is an example of chronic discoid lupus but in an area to the left, there is a prominent degree of mucinosis affecting the reticular dermis. The epidermis shows hyperplasia and hypertrophy of its superficial unit and the basal unit is inconspicuous to the right of the center of the field. It is represented only by a basal layer in some areas. The epidermal changes are less severe over the area showing prominent mucinosis, although the rete patterns are effaced. The epidermal basement membrane is coarsened and convoluted. Similar changes are manifested in the region of the follicular basement membrane. The reaction is cell-poor at the dermal-epidermal interface. To the right of the center of the field at the extremity of a hair follicle, it is richer in cells. Follicular involvement is prominent and this is a feature of variants which are sometimes associated with follicular pseudoepitheliomatous hyperplasia (LE hypertrophicus). The papillary dermis is edematous and fibrotic. Vessels are ectatic and show prominent perivascular deposits of hyalin. The prominent mucinosis is a feature of lesions of LE that are sometimes characterized as tumidus variants. It might be taken as evidence of immunostimulation but in addition must be accepted as a collagenolytic process.


 

Fig. 2: At higher magnification, the changes at the epithelial-stromal interfaces are better defined. The cellular response along the extremities of follicles is richer than that at the dermal-epidermal interface. Rete ridges are effaced and on the right, the epidermis has taken on the qualities of a hyperplastic and hypertrophied superficial unit.


 

Fig. 3:In the category of lichenoid reactions in the setting of collagen-vascular disease, the coarsened basement membrane is most characteristic of LE.


 

Fig. 4:  The epidermal changes are those of a hyperplastic and hypertrophied superficial unit. Practically, all the keratinocytes show features leading to terminal differentiation. The hypertrophy of individual keratinocytes contributes eosinophilia to the epidermis. At the tip of a blue arrow, the basement membrane is not only coarsened but also duplicated. In this same area between two lamellae there are two histiocytes. The reaction at the dermal-epidermal interface is cell-poor. Melanophages are present in the dermis near the dermal-epidermal interface. There is perivascular hyalinosis. To the right the lichenoid reaction involves a portion of a follicle.


 

Fig. 5: The tip of a follicle illustrated in Fig. 3 is seen at higher magnification.
There is coarsening and duplication of basement membrane (multiple lamellae). Inflammatory cells are trapped among the lamellae. The yellow arrow points to a melanophage. The large red arrow points to a dyskeratotic cell in the follicular epithelium. Isolated dyskeratotic (apoptotic) cells are not as prominent as in the lichenoid reaction of lichen planus. It is not a common feature for such cells (colloid bodies) to be clustered in groups in the papillary dermis in lesions of LE. There are vacuolar changes in the basal layer of the follicular epithelium. Perivascular hyalin is prominent.


 

Fig. 6: The hyperplastic superficial unit and an atrophic basal unit are represented. The basal unit shows vacuolar changes and the basement membrane is coarsened and convoluted.


 

Fig. 7: In this field, the reticular dermis shows marked mucinosis. Here, the overlying epidermis is not significantly affected by the changes usually anticipated in lesions of LE.


 

Fig. 8: In this area (an area to the left in the field illustrated in Fig. 2), mucinosis is marked. The few collagen bundles are thin and widely and irregularly spaced.  Mast cells are generally a feature of the mucinoses.

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