Lookingbill and Marks' Principles of Dermatology E-Book

James G. Marks, Jeffrey J. Miller

• Publisher: Elsevier
• Year: 2017
• ISBN:
  9780323430418
• Edition: 6
• Topic: Médecine
• Subtopic: Dermatologie

Intuitively organized by appearance rather than etiology, Lookingbill and Marks' Principles of Dermatology, 6th Edition, by Drs. James G. Marks, Jr. and Jeffrey J. Miller, is a concise, abundantly illustrated everyday reference for dermatologic diagnosis and therapy. It offers expert guidance and overviews of essential information in dermatology, including key points, clinical pearls, differential diagnosis, and tables of first- and second-line treatments. Superb clinical photographs, full-color histopathology images, and corresponding cross-sectional line diagrams provide details on cause and condition.

• Features new and expanded evidence-based treatment tables to keep you up to date with fast-changing treatments in dermatology and guide you toward the best treatments for your patients.
• Offers new coverage of common drug eruptions, as well as the latest therapies for common, difficult-to-treat skin disorders, such as acne, psoriasis, and eczema.
• Includes a more diverse range of skin color patient images throughout.

Section 1

Principles of Dermatology

1

Introduction

Key Points

1. Many outpatient visits are for dermatologic complaints

2. The patienťs chief complaint can be divided into two diagnostic skin diseases: growths and rashes

Skin diseases are common and a significant number of outpatient visits are for dermatologic complaints. A minority of these patients are seen by dermatologists; most of the remainder are seen by primary care physicians and physician extenders. In a survey of the family practice clinic at the Pennsylvania State University College of Medicine, we found that dermatologic disorders constituted 8.5% of diagnoses. The incidence is higher in a pediatric practice, in which as many as 30% of children are seen for skin-related conditions.

Although thousands of skin disorders have been described, only a small number account for most patient visits. The primary goal of this text is to familiarize the reader with these common diseases. Some uncommon and rare skin disorders are covered briefly in this book to expand the readers’ differential diagnosis.

Our diagnostic approach divides skin diseases into two large groups: growths and rashes. This grouping is based on both the patienťs presenting complaint (often a concern about either a skin growth or a symptom from a rash) and the pathophysiologic process (a growth represents a neoplastic change and a rash is an inflammatory reaction in the skin). Furthermore, the correlation between the clinical appearance of the disorder and the pathophysiologic processes responsible for the disease facilitates making the diagnosis and selecting the proper treatment.

Growths and rashes are then subdivided according to the component of skin that is affected. Growths are divided into: epidermal, pigmented, and dermal proliferative processes. Rashes are divided into those with and those without an epidermal component. We also have chapters dedicated to ulcers, disorders of the hair, nails, mucous membranes, and skin signs of systemic disease. A self-assessment chapter at the end of the text provides the learner an opportunity to reinforce diagnostic and treatment principles.

WHAT IS IT?

Figure 1.1 Growth - Melanoma.

OR

Figure 1.2 Rash - Psoriasis.

2

Structure and Function of the Skin

Chapter Contents

Epidermis

Structure

Other Cellular Components

Dermal–Epidermal Junction – The Basement Membrane Zone

Dermis

Skin Appendages

Subcutaneous Fat

Key Points

1. The major function of the skin is as a barrier to maintain internal homeostasis

2. The epidermis is the major barrier of the skin

Components of skin:

1. Epidermis

2. Dermis

3. Skin appendages

4. Subcutaneous fat

Skin disease illustrates structure and function. Loss of or defects in skin structure impair skin function. Skin disease is discussed in more detail in the other chapters.

Epidermis

Key Points

1. Keratinocytes are the principal cell of the epidermis

2. Layers in ascending order: basal cell, stratum spinosum, stratum granulosum, stratum corneum

3. Basal cells are undifferentiated, proliferating cells

4. Stratum spinosum contains keratinocytes connected by desmosomes

5. Keratohyalin granules are seen in the stratum granulosum

6. Stratum corneum is the major physical barrier

7. The number and size of melanosomes, not melanocytes, determine skin color

8. Langerhans cells are derived from bone marrow and are the skin’s first line of immunologic defense

9. The basement membrane zone is the substrate for attachment of the epidermis to the dermis

10. The four major ultrastructural regions of the basement membrane zone include the hemidesmosomal plaque of the basal keratinocyte, lamina lucida, lamina densa, and anchoring fibrils located in the sublamina densa region of the papillary dermis

Table 2.1

Skin Functions

Function	Responsible Structure
Barrier	Epidermis
● Physical	● Stratum corneum
● Light	● Melanocytes
● Immunologic	● Langerhans cells
Tough flexible foundation	Dermis
Temperature regulation	Blood vessels
	Eccrine sweat glands
Sensation	Nerves
Grasp	Nails
Decorative	Hair
Unknown	Sebaceous glands
Insulation from cold and trauma	Subcutaneous fat
Calorie reservoir	Subcutaneous fat

The epidermis is divided into four layers, starting at the dermal junction with the basal cell layer and eventuating at the outer surface in the stratum corneum. The dermal side of the epidermis has an irregular contour. The downward projections are called rete ridges, which appear three-dimensionally as a Swiss cheese-like matrix with the holes filled by dome-shaped dermal papillae. This configuration helps to anchor the epidermis physically to the dermis. The pattern is most pronounced in areas subject to maximum friction, such as the palms and sol...