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Walk the Even Hospital Database by book and chapter — the raw source passages that ground Ask, DDx, and the rest.
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The skin appendages are epidermal and dermal-derived components of the skin that include hair, nails, sweat glands, and sebaceous glands. Each component has a unique structure, function, and histology. This article describes the unique characteristics of each of these components and provides insight into tissue preparation for microscopic evaluation and the clinical significance of these structures.[1][2][3]
There are many inflammatory, immune-mediated, autoimmune, infectious, neoplastic, and traumatic causes of alterations to the normal function of the skin appendages, some of which include the following: Inflammatory and immune-mediated illnesses may result in damage to the hair follicle and can lead to permanent hair loss if the follicle scars. The follicles can become infected by various pathogens that lead to inflammation and pustule formation seen on the surface of the skin at the opening of the hair follicle. Endocrine-mediated illnesses like congenital adrenal hyperplasia, hypothyroidism, hyperthyroidism, and tumoral processes can affect hair growth and hair cycle. Trauma to the nail matrix can result in altered growth or even permanent failure of growth. Infections in the nail matrix can also alter nail growth patterns and the appearance of the nail plate. Many nail changes can present, such as pitting, koilonychia, onycholysis, ridging, among others from vitamin and nutrient deficiencies, trauma to the nail unit, psoriasis, alopecia, and many more. Sebaceous gland overactivity in conjunction with cutibacterium acnes overgrowth can cause acne or seborrheic dermatitis if there is an overgrowth of Malassezia furfur. Sebaceous glands can also become hyperplastic, form cysts, and undergo neoplastic changes. Sweat glands can become overactive, as seen in hyperhidrosis, and can contribute to excessive malodor, as seen in bromhidrosis. Many chronic conditions can result if the sweat ducts are blocked, like miliaria rubra and Fox-Fordyce disease. They, too, can undergo neoplastic changes and form tumors.[13][16]