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Dermal and Subcutaneous Growths

Key Points 1. Biopsy nodules of uncertain origin 2. Suspect cancer for hard dermal nodules Color and consistency are helpful distinguishing features. Color and consistency are helpful distinguishing clinical features. The color of the lesion sometimes reflects the nature of the proliferating elements. Vascular lesions, for example, have hues ranging from red to purple. Consistency often distinguishes a nodule from a cyst. A cyst is usually…

Pigmented Growths

Key Points 1. Melanocytes produce melanin, the skin pigment 2. When recognized early, malignant melanoma is curable Freckle Key Points 1. Sun-induced brown macules 2. Evidence of significant sun exposure and light complexion Definition A freckle (ephelis) is a brown macule found in sun-exposed areas of the skin ( Fig. 6.1 ). The amount of melanin in the basal area of the epidermis is increased, with…

Epidermal Growths

Key Points 1. Proliferation of keratinocytes or basal cells 2. Scaling usually prominent 3. Bleeding or crusting suggests cancer Actinic Keratosis Key Points 1. Precancerous 2. Prevent with sun protection Definition Actinic (solar) keratosis is a precancerous neoplasm of the epidermis caused by the ultraviolet (UV) portion of sunlight. The abnormal keratinocytes in actinic keratoses are confined to the epidermis and constitute a premalignant change. The…

Dermatologic Therapy and Procedures

Principles of Topical Therapy Key Points 1. Many types of drug are available in topical preparation 2. The vehicle is almost as important as the active ingredient 3. Give enough volume to treat the area of disease involvement adequately A diverse group of medications is available in topical preparations, including antibiotics, antifungals, corticosteroids, acne preparations, sunscreens, cytotoxic agents, antipruritics, antiseptics, and pesticides. Topical therapy has the…

Principles of Diagnosis

Key Points 1. Morphologic appearance is critical in making the diagnosis 2. Skin diseases can be divided into growths and rashes Steps in dermatologic diagnosis: 1. History 2. Physical: identify the morphology of basic lesion 3. Consider clinicopathologic correlations 4. Configuration or distribution of lesions (when applicable) 5. Laboratory tests In history taking, a modified format is suggested. Instead of beginning with an exhaustive interrogation, it…

Structure and Function of the Skin

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…

Dermatologic Surgical Procedures

Punch biopsy, shave biopsy, electrodesiccation and curettage (ED&C), blunt dissection, and simple excision and suture closure are the basic techniques that should be learned by physicians who treat skin disease. One should be familiar with the more sophisticated techniques, such as Mohs micrographic surgery, so that referral to physicians who perform these techniques can be made at the proper time. The instruments used for most basic…

Cutaneous Manifestations of Internal Disease

Certain cutaneous diseases are frequently associated with internal disease. The skin disease itself may be inconsequential, but its presence should prompt investigation of possible related internal disorders. A selected group of such diseases is discussed in this chapter. Pigmentary skin changes associated with internal diseases are also discussed in Chapter 19 . Cutaneous Manifestations of Diabetes Mellitus Approximately 30% of patients with diabetes mellitus develop a…

Nail Diseases

See pages 963–964 for photos of the most common nail disorders. Anatomy and Physiology Anatomy The nail unit consists of several components ( Fig. 25.1 ). The nail plate is hard, translucent, dead keratin. The nail fold includes the skin surrounding the lateral and proximal aspects of the nail plate. The proximal nail fold overlies the matrix. Its keratin layer extends onto the proximal nail plate…

Hair Diseases

Physicians are frequently confronted with hair-related problems. Most complaints are from patients with early-onset pattern baldness. The physician must be able to recognize this normal, inherited hair loss pattern so that detailed and expensive evaluations can be avoided. Other patients have complaints about abnormal hair growth; these diseases must be recognized and not dismissed as balding. The signs of hair loss or excess growth are at…

Vascular Tumors and Malformations

Congenital Vascular Lesions A number of different congenital vascular lesions occur in the skin. The two major categories are vascular tumors (growths) and vascular malformations. Many represent developmental malformations and do not appear to be genetically determined, although the genetic basis for many vascular malformations is known. Vascular structures may be abnormal in size, abnormal in numbers, or both. These varied lesions have been referred to…

Nevi and Malignant Melanoma

Melanocytic Nevi Nevi, or moles, are benign tumors composed of nevus cells that are derived from melanocytes. Many myths surround moles, for example, that hairs should not be plucked from moles or that moles should not be removed or disturbed. Nevus Cells The nevus cell differs from melanocytes. The nevus cell is larger, lacks dendrites, has more abundant cytoplasm, and contains coarse granules. Nevus cells aggregate…

Premalignant and Malignant Nonmelanoma Skin Tumors

Basal Cell Carcinoma Basal cell carcinoma (BCC) is the most common invasive malignant cutaneous neoplasm found in humans. The most common presenting complaint is a bleeding or scabbing sore that heals and recurs. Unfortunately, there is a tendency to regard BCC as nonmalignant because the tumor rarely metastasizes. BCC advances by direct extension and destroys normal tissue. Left untreated or inadequately treated, the cancer can destroy…

Benign Skin Tumors

Seborrheic Keratosis Seborrheic keratosis (SK) and nevi are the most common benign cutaneous neoplasms. SKs are of unknown origin and have no malignant potential. In recent years, somatic mutations in the fibroblast growth factor receptor 3 ( FGFR3 ) gene (more likely seen in histologic acanthotic and adenoid SKs) and p100α subunit of phosphoinositide 3-kinase (PIK3CA) (more likely in histologic hyperkeratotic SKs) oncogenes have been found…

Light-Related Diseases and Disorders of Pigmentation

Photobiology Sunlight has profound effects on the skin and is associated with a variety of diseases ( Boxes 19.1 to 19.3 , Table 19.1 ). Ultraviolet (UV) light causes most photobiologic skin reactions and diseases. The accepted unit for measurement of the wavelength of light is the nanometer (nm). The solar radiation that reaches the earth is a continuous spectrum consisting of wavelengths of electromagnetic energy…

Hypersensitivity Syndromes and Vasculitis

Hypersensitivity Syndromes Hypersensitivity syndromes are displayed in Fig. 18.1 . Erythema Multiforme Erythema multiforme (EM) is a relatively common, acute, often recurrent inflammatory disease. Many factors have been implicated in the etiology of EM, including numerous infectious agents, drugs, physical agents, X-ray therapy, pregnancy, and internal malignancies ( Box 18.1 ). In approximately 50% of cases no cause can be found. EM is commonly associated with…

Connective Tissue Diseases

Autoimmune Diseases Diseases that result from attack by one's own immune system are called autoimmune diseases. Autoimmune diseases are organ-specific illnesses or systemic illnesses such as systemic lupus erythematosus (SLE) ( Table 17.1 ). Autoimmune diseases are associated with circulating autoantibodies, which bind self-protein. Pathogenesis may then be mediated by autoimmune T lymphocytes and other immune mechanisms. Autoantibodies either are responsible for the manifestations of autoimmune…

Vesicular and Bullous Diseases

Blisters Vesicles and bullae are the primary lesions in many diseases. Some are of short duration and are quite characteristic, such as those in poison ivy and herpes zoster. In other diseases, such as erythema multiforme and lichen planus, a blister may or may not occur during the course of the disease. Finally, there is a group of disorders in which bullae are present almost continuously…