13.1 Dermatophytosis (tinea) (see Fig. 13.1A–G ) Very common superficial cutaneous infection by one of the three genera: Microsporum , Epidermophyton , and Trichophyton . Scaly, erythematous plaques, often annular (1.5, hence sometimes called “ringworm”), sometimes pustular, rarely vesicular (1.147).…
12.1 Impetigo (see Fig. 12.1A–D ) Common superficial infection with Staphylococcus aureus and/or Streptococcus pyogenes . Most common in children, especially around mouth, nose (1.95), axilla, or groin (1.55). Honey-colored crusts and an acute onset are typical. Glomerulonephritis (1.66) is…
11.1 Ichthyosis (see Fig. 11.1A–D ) Although ichthyosis (from Greek ichthys, meaning fish skin; “sauriasis,” from Greek sauros meaning lizard skin, like a dinosaur, as opposed to “psoriasis”) has traditionally been divided into four major groups (the first four listed…
These are inflammatory diseases involving sweat glands or pilosebaceous units. 10.1 Acne (see Fig. 10.1A–E ) Very common disorder, open comedones (blackheads), closed comedones (whiteheads), red papules , pustules , cysts (ruptured inflamed sebaceous glands without an epithelial lining as…
9.1 Solar elastosis (see Fig. 9.1A,B ) Very common parched or wrinkled skin due to sun damage (dermatoheliosis) with degeneration of connective tissue (increased abnormal elastic tissue and less collagen). ■ Amorphous, fibrous, or globular basophilic material in the dermis…
8.1 Porphyria (see Fig. 8.1A–F ) Uncommon to rare group of porphyrin metabolism disorders. Most of them present as photodermatitis (1.110) with papules or vesicles mostly on sun-exposed skin. Pathology 1. Porphyria cutanea tarda (PCT): most common type of porphyria,…
A discussion of granulomas and their differential diagnoses appears in section 1.51. Granulomas can occasionally resemble other non-granulomatous diseases with epithelioid cells (1.38). 7.1 Granuloma annulare (GA) (see Fig. 7.1A–E ) Common idiopathic non-scaly annular plaques (1.5) and erythematous papules,…
A list of vesiculobullous diseases appears in section 1.147. Some subepidermal diseases can appear to be intraepidermal when they have re-epithelialized. Usually, the blister will have a smooth base in that case. The following diseases may sometimes produce subepidermal blisters,…
The classification of vesicles and bullae are discussed in general in Section 1.147. Many of them are not discussed in this chapter. Some subepidermal diseases can appear to be intraepidermal when they have re-epithelialized. Intraepidermal diseases can also appear subepidermal…
These diseases are all characterized by vascular damage of some type. Extravasated erythrocytes (1.40) often produce the appearance of purpura (1.120). Some of these diseases are considered to be true vasculitis. Vasculitis (literally, inflammation of the blood vessels) cannot be…