S5C19VA2-1: This drawing depicts two pathways along either of which the nature of the dermal connective tissue might be altered. The upper pathway leads to a mucinosis with a reduction in the collagenous component of the dermis. The lower pathway leads to a sclerosing collagenosis of the dermis (in the drawing, this option is expressed in sclerodermoid patterns in which collagen bundles are coarsened and arranged in parallel arrays [lower pathway]). Note that a mucinosis also might evolve into a sclerodermoid process. Such a sequence is common in chronic forms of scleredema adultorum.

S5C19VA2-2: This drawing presents the basement membrane zone and the neighboring papillary dermis as an immunologic barrier. In this drawing, the barrier has been violated locally at the dermal-epidermal interface and also at the extremity of a follicle. The model for this pattern could be either LE or dermatomyositis, but the concept has application to other inflammatory processes. An intact basement membrane is a barrier to regenerating fibroblasts of the papillary dermis. If a process such as lichen planus damages the basement membrane, fibroblasts may gain access to defects in the epidermal domain; those, that do, inlay the defects with fibrous tissue. Defects in basement membrane probably account for the sclerosing reactions in lesions of cicatricial pemphigoid and epidermolysis bullosa acquisita. The barrier also functions in an inverse manner; in some lichenoid reactions in the face of defects in this immunologic barrier, regenerating epidermis or follicular epithelium is predisposed to violate the barrier and to then invade the dermis (pseudoepitheliomatous hyperplasia).

MUCINOSIS

1. eosinophilia-myalgia syndrome

2. acral persistent papular mucinosis

3. self-healing juvenile cutaneous mucinosis

4. cutaneous mucinosis of infancy

S5C19VA2-3: The category of cutaneous mucinosis has been expanded (complicated?) by recent additions.

PIGMENTED LICHENOID REACTIONS

1. lichen planus

2. berloque dermatitis

3. poikiloderma of Civatte

4. drug

5. macular and lichen amyloidosis

S5C19VA2-4: Lichenoid reactions may lead to patterns of abnormal pigmentation, either hypopigmentation or hyperpigmentation. Basal melanocytes are affected by the lichenoid processes. Perhaps melanized products are the nidi in which some antigenic agents become embedded and fixed in the skin. Both keratins and amyloids are beta-pleated proteins. Keratinocytes are assumed to be the source of amyloid in the macular and papular forms of amyloidosis. In these two variants of amyloidosis, the basic patterns at the dermal-epidermal interface are lichenoid.

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