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…
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…
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…
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…
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…
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…
Scabies Human scabies is a highly contagious disease caused by the mite Sarcoptes scabiei var. hominis . The mite is an obligate parasite to humans. Scabies is not primarily a sexually transmitted disease, but sexual transmission does occur ( Table…
The word exanthem means a skin eruption that bursts forth or blooms. Exanthematous diseases are characterized by widespread, symmetric, erythematous, discrete, or confluent macules and papules that initially do not form scale. Exanthematous disease is one of the few diseases…
Dermatophyte Fungal Infections These dermatophytes include a group of fungi (ringworm) that under most conditions have the ability to infect and survive only on dead keratin (that is, the top layer of the skin – the stratum corneum or keratin…
Warts Warts are benign epidermal neoplasms that are caused by human papillomaviruses (HPVs), which are small DNA viruses. There are more than 100 different types of HPVs, and new types are discovered each year. HPVs infect epithelial cells of the…