Fenske N A, Lober C W
J Am Acad Dermatol. 1986 Oct;15(4 Pt 1):571-85. doi: 10.1016/s0190-9622(86)70208-9.
Solar-induced cutaneous changes are more prevalent and profound in older persons and, thus, are often inappropriately attributed to the aging process, per se. Structural and functional alterations caused by intrinsic aging and independent of environmental insults are now recognized in the skin of elderly individuals. Structurally the aged epidermis likely becomes thinner, the corneocytes become less adherent to one another, and there is flattening of the dermoepidermal interface. The number of melanocytes and Langerhans cells is decreased. The dermis becomes atrophic and it is relatively acellular and avascular. Dermal collagen, elastin, and glycosaminoglycans are altered. The subcutaneous tissue is diminished in some areas, especially the face, shins, hands, and feet, while in others, particularly the abdomen in men and the thighs in women, it is increased. The number of eccrine glands is reduced and both the eccrine and apocrine glands undergo attenuation. Sebaceous glands tend to increase in size but paradoxically their secretory output is lessened. The nail plate is generally thinned, the surface ridged and lusterless, and the lunula decreased in size. There is a progressive reduction in the density of hair follicles per unit area on the face and scalp, independent of male-pattern alopecia. The hair shaft diameter is generally reduced but in some areas, especially the ears, nose, and eyebrows of men and the upper lip and chin in women, it is increased as vellus hairs convert to cosmetically compromising terminal hairs. Functional alterations noted in the skin of elderly persons include a decreased growth rate of the epidermis, hair, and nails, delayed wound healing, reduced dermal clearance of fluids and foreign materials, and compromised vascular responsiveness. Eccrine and apocrine secretions are diminished. The cutaneous immune and inflammatory responses are impaired, particularly cell-mediated immunity. Clinical correlates of these intrinsic aging changes of the skin include alopecia, pallor, xerosis, an increased number of benign and malignant epidermal neoplasms, increased susceptibility to blister formation, predisposition to injury of the dermis and underlying tissues, delayed onset and resolution of blisters and wheals, persistent contact dermatitis, impaired tanning response to ultraviolet light, increased risk for wound infections, prolongation of therapy necessary for onychomycosis, and thermoregulatory disturbances.
日光引起的皮肤变化在老年人中更为普遍和显著，因此常常被不恰当地归因于衰老过程本身。现在人们认识到，老年人皮肤中存在由内在衰老引起且与环境损伤无关的结构和功能改变。在结构上，老年表皮可能变薄，角质形成细胞之间的黏附性降低，真皮表皮界面变平。黑素细胞和朗格汉斯细胞数量减少。真皮萎缩，相对细胞成分少且血管少。真皮中的胶原蛋白、弹性蛋白和糖胺聚糖发生改变。皮下组织在某些区域减少，尤其是面部、小腿、手部和足部，而在其他区域，特别是男性的腹部和女性的大腿部，则会增加。汗腺数量减少，小汗腺和大汗腺都出现萎缩。皮脂腺往往体积增大，但矛盾的是其分泌量减少。指甲板通常变薄，表面有纹路且无光泽，甲半月变小。面部和头皮每单位面积的毛囊密度逐渐降低，与男性型脱发无关。毛干直径通常减小，但在某些区域，尤其是男性的耳朵、鼻子和眉毛以及女性的上唇和下巴，随着毳毛转变为影响美观的终毛，毛干直径会增大。老年人皮肤中观察到的功能改变包括表皮、毛发和指甲的生长速度减慢、伤口愈合延迟、真皮对液体和异物的清除减少以及血管反应性受损。小汗腺和大汗腺分泌减少。皮肤免疫和炎症反应受损，尤其是细胞介导的免疫。皮肤这些内在衰老变化的临床相关表现包括脱发、面色苍白、皮肤干燥、良性和恶性表皮肿瘤数量增加、水泡形成易感性增加、真皮和深层组织易受伤、水泡和风团的发生和消退延迟、持续性接触性皮炎、对紫外线的晒黑反应受损、伤口感染风险增加、甲癣治疗所需时间延长以及体温调节紊乱。
