|
Porphyria: Some cutaneous
manifestations of porphyria are non-bullous; some lesions are sclerotic. The areas of sclerosis do not necessarily correspond to the acral, or sun-exposed sites that are commonly involved by bullous lesions. On the other hand, even in lesions of the sun-exposed sites, there often is some degree of sclerosis. It may be incorrect to label the sclerosing changes in lesions of porphyria as sclerodermoid, if the intention of such a designation is to direct the pathologist to a search for changes that resemble those of scleroderma.
If a non-bullous lesion of porphyria is biopsied, the histologic patterns qualify as a cell-poor lichenoid reaction at the
dermal-epidermal interface. The patterns might be characterized as somewhat lupus erythematosus-like, but lacking the lymphoid infiltrates. The epidermis shows hyperkeratosis and hypertrophy of keratinocytes of the
superficial unit of the epidermis. The basal layer shows vacuolar changes. The epidermal kinetics are shifted to the part of the spectrum that promotes keratinization of cells and away from the part in which
replication of cells is promoted (i.e., a distinct basal unit ceases to be a distinctive feature).
The sclerosis occurs in the upper portion of the dermis; it involves the papillary dermis and the adjacent reticular dermis. The
patterns are somewhat comparable to those of superficial morphea. The anatomic compartments, that are affected, are the same as those of lesions of lichen sclerosis et atrophicus.
A thickened basement membrane may be a feature of the reaction at the dermal-epidermal interface. In addition, hyaline deposits in
membranous patterns may be a feature of the small vessels in the areas of dermal fibrosis. Apparently, some of the affected vessels are obliterated.
There are rare examples in which the sclerosing changes do resemble those of scleroderma.
Lupus erythematosus: That anatomic site, which is affected in lesions of both superficial morphea and lichen sclerosis et atrophicus, is the same as the site which shows significant alterations in lesions of discoid lupus erythematosus. In rare examples of LE, the epidermis is hyperplastic and rete ridges are elongated; the basal unit is hyperplastic. The patterns in such lesions are ambiguous; a resolving lichen planus-like process must be considered in the differential diagnosis.
For some lesions of LE, the patterns may suggest a diagnosis of LS&A. Edema of a widened papillary dermis may resemble the
edema and hyalinization of the upper portion of the dermis in a lesion of LS&A. A thickened basement membrane is a feature favoring a diagnosis of LE, but
sclerosis and hyalinization in the basement membrane zone is seen in some early lesions of LS&A. In some lesions of LE, the upper portion of the reticular dermis shows patterns of sclerosis in which collagen bundles are arranged in parallel arrays (a sclerodermoid quality). Perivascular hyalin is a prominent feature of lesions of discoid LE.
|
