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KEY POINTS

Key Points

  • image The epidermis consists of continually regenerating stratified epithelium, and 90% of cells are ectodermally derived keratinocytes.

  • imagePilosebaceous units are lined by the germinal epithelium of the epidermis and thus serve as an important source of epidermal regeneration after partial-thickness injury or split-thickness skin graft.

  • image Dermal fibers are predominantly made of type I and III collagen in a 4:1 ratio. They are responsible for the mechanical resistance of skin.

  • image The drugs most commonly associated with epidermal necrolysis include aromatic anticonvulsants, sulfonamides, allopurinol, oxicams (nonsteroidal anti-inflammatory drugs), and nevirapine.

  • image In wounds being allowed to heal secondarily, negative pressure wound therapy can increase the rate of granulation tissue formation.

  • image Staphylococcus aureus is the most common isolate of all skin infections. Impetigo, cellulitis, erysipelas, folliculitis, furuncles, and simple abscesses are examples of uncomplicated infections, whereas deep-tissue infections, extensive cellulitis, necrotizing fasciitis, and myonecrosis are examples of complicated infections.

  • image Hemangiomas arise from benign proliferation of endothelial cells surrounding blood-filled cavities. They most commonly present after birth, rapidly grow during the first year of life, and gradually involute in most cases.

  • image Basal cell carcinoma represents the most common tumor diagnosed in the United States, and the nodular variant is the most common subtype. The natural progression of basal cell carcinoma is one of local invasion rather than distant metastasis.

  • image Squamous cell carcinoma is the second most common skin cancer, and typically arises from an actinic keratosis precursor. Primary treatment modalities are surgical excision and Mohs microsurgery. Cautery and ablation, cryotherapy, drug therapy, and radiation therapy are alternative treatments.

  • image Tumor thickness, ulceration, and mitotic rate are the most important prognostic indicators of survival in melanoma. Sentinel lymph node biopsy is often used to stage individuals with biopsy-proven high risk melanoma and clinically node-negative disease.

INTRODUCTION

The skin is a complex organ encompassing the body’s surface and is continuous with the mucous membranes. Accounting for approximately 15% of total body weight, it is the largest organ in the human body. Enabled by an array of tissue and cell types, intact skin protects the body from external insults. However, the skin is also the source of a myriad of pathologies that include inflammatory disorders, mechanical and thermal injuries, infectious diseases, and benign and malignant tumors. The intricacies and complexities of this organ and associated pathologies are reasons the skin and subcutaneous tissue remain of great interest and require the attention of various surgical disciplines that include plastic surgery, dermatology, general surgery, and surgical oncology.

ANATOMY AND HISTOLOGY

Background

It is important that surgeons understand completely the cutaneous anatomy and its variability as they play an enormous role in patient health and satisfaction. The skin is made up of tissues derived from both the ectodermal and mesodermal germ cell layers.1 Three distinct tissue layers comprise the organ, and differ in composition based on location, age, sex, and ethnicity, among other ...

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