|
Cicatricial Pemphigoid (tier 2)
In this presentation, a basic premise, one that influences the interpretations, holds that the lesions in this category are chronically localized; they are relatively “fixed” (S6C19P13-1-7). In addition, certain histologic features might be taken as markers favoring an early
lesion. Other features can be taken as markers for chronicity; they are indicative of lesions late in their evolution. With these guidelines, the histologic patterns of lesions might be characterized as:
1. acute (neutrophilic phase with no evidence of sclerosis) phase (S6C20P14-1)
2. fibrosing phase (S6C20P14-2-4)
3. combinations of the two (chronic, active lesions)
4. Quiescent phase
In early lesions, the most striking changes occur at the dermal-epidermal interface; neutrophils concentrate at this interface. They may undergo lysis and, in the process, basal
keratinocytes and stroma at the dermal-epidermal interface are damaged. The epidermis separates from the papillary dermis; fibrin is deposited in the defect; it condenses along the floor of the defect (S6C21P15-1). The breakdown of inflammatory cells contributes a distinct basophilia in areas of the condensed fibrin. The
features of the condensed fibrin and the break-down of inflammatory cells set this disorder apart from the usual examples of bullous pemphigoid. Connective tissue, particularly at the tips of denuded papillae, shows
partial lysis of connective tissue fibers, including basement membrane (S6C22P16-1-3). The lytic process affects both
collagenous and elastic fibers. The damaged dermal papillae are often thin and elongated; the vessels of the dermal papillae extend close to the surface of the respective papilla. In the process of repair,
fibroblasts of the damaged papillae proliferate; some of these fibroblasts extend through the damaged basement membrane into the condensed fibrin along the surface of the floor of the defect (S6C23P17-1-5). New fibrous tissue is inlaid in condensed fibrin of the defect (a process that qualifies as organization); it may
be deposited in sequential patterns. What appears to be a widened papillary dermis takes on the qualities of granulation tissue; actually, much of the fibrous matrix is newly formed. The process leading to this
formation of new connective tissue, might be characterized as accretive, or appositional growth. The fibrosis along the surface of the defect results in an expansion of dermal connective tissue; the papillary
dermis, in the process of organization, blends with the expanding granulation tissue. In this manner, the combination of organizing granulation tissue and papillary dermis presents the pattern of an expanded
papillary dermis. It is expanded along a vertical axis (a vector perpendicular to both a plane which is parallel to the surface of the papillary dermis and to a plane parallel to the surface of the skin).
Although the fibrosing process alters the character of the fibrous tissue of the papillary dermis, dermal papillae, although covered by a mat of granulation tissue, are, for a time, preserved in outline. Eventually,
the fibrosing reaction obliterates the clefts among the dermal papillae. The surface of the floor is straight from side to side; the undulating surface associated with projections of dermal papillae is obliterated (S6C24P18-1-5, & S6C25P19-1-7). The
vascular patterns of the newly formed fibrous tissue are abnormal (S6C26P20-1-3). Some of the vessels are dilated and do not
contain red blood cells. They show branching patterns and might best be interpreted as lymphatics. These many features are represented in photomicrographs (S6C21P15-1-3 & 5-6).
In chronic eroded lesions, the papillary dermis is widened and edematous. Perivascular infiltrates are prominent; they are composed of lymphocytes, histiocytes, and plasma cells.
Lesions of discoid LE also can be relatively “fixed” on the scalp (S6C21P15-4).
Smoldering, relatively quiescent, lesions of cicatricial pemphigoid may show lichenoid qualities.
|
