S9C21aP13aConnectiveNevus

S9C21aP13a-1: This is another example of a connective tissue nevus showing hyperplasia of dermal collagen; collagen bundles are coarsened; there is a broad expanse without representation of skin appendages. The vertical dimensions of the dermis are increased. Green arrows point to parallel bundles of collagen (retinacular components). In the retinacula, collagen bundles, that are relatively straight, are clustered; they are directed obliquely through the dermis. Among the retinacula, collagen bundles, that are clustered, mostly are cut in cross section. Retinacular patterns of this type may be encountered in normal skin, particularly the dorsal trunk, but are exaggerated in connective tissue nevi.

S9C21aP13a-2: In this field, there is increased complexity of the pattern in which collagen bundles are distributed. In addition, pale, faintly basophilic fibers (elastic fibers) encircle individual collagen bundles. The patterns are those of nevus elasticus and are of a type associated with osteopoikilosis.

S9C21aP13a-3: With a Verhoeff van Giesen stain, the pattern of elastic fibers is abnormal. The fibers focally are increased in number; they are coarse. Some of the elastic fibers encircle collagen bundles. Elastic fibers are black; collagen bundles are an off-red.

S9C21aP13a-4: Elastic fibers are increased in number; they are coarse and irregular in outline. In areas, individual elastic fibers partially encircle individual collagen bundles. Some of the elastic fibers appear to be entrapped in collagen bundles (connective tissue nevus; Verhoeff-van Giesen stain).

S9C21aP13a-5: This is the characteristic pattern of a scratch papule. The epidermis shows hyperkeratotis, parakeratosis, and elongation of rete ridges. There is papillomatosis. The papillary dermis is widened and fibrotic. The fibrous tissue is rather homogeneous; lamellar fibrosis usually is not a prominent feature. Vessels are ectatic and increased in number in the widened papillary dermis. Lesions, of this type, often are essentially free of infiltrates of inflammatory cells.

S9C21aP13a-6: The lesion is both a verrucoid epidermal hyperplasia and a fibrosing process of the papillary dermis. There may also be fibrosis of the reticular dermis but, in the latter location, the patterns are less characteristic. The changes in the papillary dermis are a great aid in diagnosis (scratch papule).

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