S9C21P13-4: In some lesions, as a variation in patterns, there are nodular components. Over the nodule to the left, the epidermis is thin; it has separated from the dermis. The cleft contains red blood cells. The epidermal changes in this area are compatible with a response to external trauma and to the upward pressure exerted by the tumor. The lesion is fibrotic. Near the area in which epidermis has separated from the dermis, the matrix of the nodular component is richly vascularized (granulation tissue-like). The changes are compatible with prurigo nodularis. Often such lesions show a hyperplasia of small nerves; the affected nerves, when represented, show Schwann cell hyperplasia.

S9C21P13-5: A pure pattern of a collagenosis is found in this connective tissue nevus. In this example, broad bands of coarse, parallel collagen bundles extend obliquely across the field (green arrows). In these bands, the collagen bundles are straight and parallel in an oblique orientation. They are not parallel to the surface of the skin, as in the collagenosis of morphea. In addition, and unlike the patterns of morphea, there is no evidence of a lymphohistiocytic interstitial infiltrate (the lymphohistiocytic collagenosis of morphea). In this setting, a Verhoeff van Gieson stain is indicated to evaluate the component of elastic fibers.

S9C21P13-6: The diagonally directed bands of collagen bundles (green arrows) are an accentuation of patterns normally seen in the reticular dermis, particularly in sites with considerable vertical dimensions, such as the dorsum of the thorax. The bands might be characterized as dermal retinacula; in this approach, the pattern in some connective tissue nevi qualify in part as hyperplasia of dermal retinacula.