Evolution. Some lesions quickly attain complete formation
without any intermediate stage (macules). Certain others remain the same
(warts) during their entire existence. Other lesions develop into different
primary lesions, as the papulovesicles becoming pustules, and may be present in
all stages of evolution. Some lesions show marked alterations, due to
conglomeration or confluence.
Involution
Certain lesions disappear completely,
whereas others leave pigment or scars, and still others do not involute.
Grouping
Certain lesions tend to be grouped
in clusters, as in herpes zoster; or in a concentric manner, as in erythema
iris. Grouping is a characteristic of dermatitis herpetiformis and of late
secondary and tertiary syphilitic eruptions. In dermatoses due to bacteria and
fungi, a cluster of lesions may be the result of the development of small new
ones around the original lesion by the spreading of infection. Flea and other
insect bites are usually grouped.
Configuration
There is a tendency in some lesions to assume characteristic figures, either by
enlargement or by coalescence. Circinate and annular lesions are encountered in
ringworm, syphilis, erythema multiforme, lichen planus, psoriasis, seborrheic
dermatitis, and pityriasis rosea. Gyrate patterns are formed in psoriasis,
mycosis fungoides, and sometimes in syphilis. Serpiginous arrangement is a
characteristic of tertiary syphilis of the skin and occasionally of rodent
ulcer. In some syphiloderms and in the configurate type of seborrheic
dermatitis, there are crescentic formations. Some grotesque and bizarre
patterns are found in mycosis fungoides, the other lymphoblastomas, and in dermatitis artefacta.
Color
It is not advisable to place too much reliance on the color of lesions as a
diagnostic factor, for it is difficult to describe colors, and they appear
differently to different individuals; but they may at least serve as a
corroborative aid. In mycosis fungoides, scarlet fever, erysipelas, erythema
multiforme, xanthoma, steatoma multiplex, secondary syphilis, lupus vulgaris
and many other diseases the characteristic color is a diagnostic aid.
Patches lighter in color than the normal skin suggest
leukoderma, and when mottled about the neck, syphilis. Patches of seborrheic
dermatitis in Negroes may be light in color. Tinea versicolor in brunettes may
produce a semblance to white spot disease, morphea guttata, or lichen sclerosus.
Leprosy, scleroderma, and cicatrix may produce lesions lighter in color than
the normal skin. Lesions darker in color may be inflammations, nevi,
lentigines, or hyperpigmentations—such as occur in chloasma, accompanying
scars, from pressure or rubbing, due to arsenic, or to bismuth or lead in the
gums; or when generalized or profuse, as a sequel of lichen planus.