Ch8 Hair Follicles

Buster (the plight of feral cats)

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F1Ch8 (103057): Hyperplastic sebaceous glands are present at the margins of this fibrous papule. Centrally, there are miniaturized, immature follicles, two of which have there extremity oriented in a direction that parallels the surface of the skin; there is perifollicular fibrosis. Focally, rete patterns are effaced. Dilated vessels are most prominent near the surface, and are irregular in distribution. A normal papillary dermis is not a feature. The fibrosing process extends close to the lower margin of the biopsy; its extends into the domain of the reticular dermis.

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F2Ch8 (103057): On the right, the ostium of a follicle is dilated; it contains keratinized debris; the infundibular epithelium is hyperplastic.

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F3Ch8 (103057): Coarse collagen bundles extend to the dermal-epidermal interface. In the dermal papilla on the left, the bundles form vertically oriented, parallel arrays. The granular layer of the epidermis uniformly is hyperplastic. On the right, the rete patterns are effaced. In this area, the basement membrane area focally is widened and brightly acidophilic. Dilated vessels focally are increased in number. Near the bottom of the field, the adventitial space is expaned; there are loose, perivascular infiltrates of lymphoid cells. A follicle on the right, near the bottom of the field, shows an expanded perifollicular matrix; the follicle shows catagen phenomena. Some of the collagen bundles of the neighboring dermis form parallel arrays.

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F4Ch8 (103049): This example bulges at the surface in a polypoid pattern. Rete patterns are mostly effaced and, focally, the epidermis is thin. Miniaturized follicles have expanded follicular sheaths. There is an increased number of dilated vessels; some of the vessels have thick walls.

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F5Ch8 (113049): In this field, the epidermis shows a sharply defined division between the superficial and the basal units of the epidermis. A brightly acidophilic basement membrane is irregularly represented along the dermal-epidermal interface. Lamina of similar material extend a short distance into the upper portion of the reticular dermis. The smudgy column of hyalin that projects from the left margin of the field is interpreted as a hyalinized follicular sheath. A follicle, cut in cross-section, is outlined by fibrous lamina. The lower 1/3 of the field shows lysis of the collagenous component. Above this level, collagen bundles tend to be vertically oriented. Vessels are increased in number and dilated. One vessel near the interface between the more fibrous portion of the dermis and the area showing collagenolysis shows an area of bright acidophilia (exudative lesion).

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F6Ch8 (113049): The epidermis shows hyperplasia of the superficial unit and mild hyperplasia of the basal unit of the epidermis. The follicle on the right shows laminated perifollicular fibrosis. The wedge of the bulb has developed. The two follicles to the left show perifollicular sclerosis and hyalinization of the perifollicular sheath. Some of the dilated vessels show concentrically reduplicated basement membranes. A pale acidophilic matrix has collected among the abnormal collagen bundles of the reticular dermis. There is no evidence of a normal papillary dermis.

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