Tutorial C: Patterns and Distribution

Annular lesions are seen in a ring shape. Tinea corporis, erythema migrans (the lesion associated with lyme disease), and granuloma annulare are three common examples.

Discrete lesions tend to remain separate. This is a helpful descriptive term but has little specific diagnostic significance.

Clustered lesions are those that are grouped together. They are commonly seen in herpes simplex or with insect bites, for example.

Confluent lesions tend to run together.

Dermatomal, zosteriform lesions follow a dermatome. The lesions of varicella zoster (also known as shingles) are the classic example, but there are other lesions that may assume the same pattern.

Eczematoid lesions are inflamed with a tendency toward clustering, oozing, or crusting.

It is sometimes helpful to determine if lesions specifically involve the hair follicle.

Guttate lesions look as though someone took a dropper and dropped this lesion on the skin. Guttate lesions are characteristic of one form of psoriasis, though that is not the only example.

The Koebner phenomenon, also called the isomorphic response, refers to the appearance of lesions along a site of injury. This phenomenon is seen in a variety of conditions; for example, lichen planus, warts, molluscum contagiosum, psoriasis, lichen nitidus, and the systemic form of juvenile rheumatoid arthritis.

Linear lesions occur in a line or band-like configuration. This descriptive term may apply to a wide variety of disorders. (One should be certain that the lesions are not following a dermatome.)

Patients with multiform lesions have lesions of a variety of shapes.

Reticular or net-like lesions can be seen in a variety of circumstances; e.g., very commonly in newborns (or even grown children and adults) as cutis marmorata, or with livedo reticularis. The former fades as the skin is warmed the latter becomes more florid.

Serpiginous lesions wander as though following the track of a snake.

Universalis refers to a widespread disorder that affects the entire skin.

Scarlatiniform rashes have the pattern of scarlet fever. The patient with a scarlatiniform rash has innumerable small red papules that are widely and diffusely distributed. Note that the term scarlatiniform does not mean that the patient has scarlet fever, although by definition all patients with scarlet fever have a scarlatiniform rash. Patients with a variety of other conditions such as Kawasaki disease, viral infections, or drug reactions may have rashes with the same pattern.

Patients with scarlet fever, Kawasaki disease or other conditions may develop a distinctive appearance of their tongues. Because of its resemblance to the well-known berry, the appearance is called “strawberry tongue.” Since this eruption is on a mucus membrane, it is called an enanthem.

The term “morbilliform” means that the patient has a rash that looks like measles. Patients with measles will have the rash but patients with Kawasaki disease, drug reactions, or other conditions may also have a morbilliform rash. The rash consists of macular lesions that are red and are usually 2-10 mm in diameter but may be confluent in places.

The term is commonly used to describe a portion of the rash of cutaneous candidiasis in which a beefy red plaque may be found surrounded by numerous, smaller red macules located adjacent to the body of the main lesions.

One important category of skin lesions involve the form that skin lesions may take in cases of child abuse or other intentional injury (bite marks, slap marks, strap marks, burns, etc.) or in cases of unintentional injury. Abrasions are traumatically caused erosions.