Measles is to be differentiated by its catarrhal symptoms, fever, form and situation of the eruption; roetheln, by its small, roundish, confluent pinkish or reddish patches, its precursory pyrexic symptoms, its epidemic nature, and short duration; tinea versicolor by its scaliness, peripheral growth, distribution and history. And, finally, by the absence or presence of other symptoms of syphilis. [Illustration: Fig. 51. Macular Syphiloderm.] #What several varieties of the papular eruption of syphilis are met with?# There are two forms of the papular eruption--the small and large; those of the latter type may undergo various modifications. #Describe the small-papular eruption of syphilis.# The _small-papular syphiloderm_ (_miliary papular syphiloderm_) usually shows itself in the third or fourth month of the disease, and consists of a more or less generalized eruption of disseminated or grouped, firm, rounded or acuminated pin-head to millet-seed-sized papules, with smooth or slightly scaly summits, and in some lesions showing pointed pustulation. Scattered minute pustules and some large papules are usually present. The eruption is profuse, most abundant upon the trunk and limbs; and in the early part of the outbreak is of a bright- or dull-red color, later assuming a violaceous or brownish tint. It runs a chronic course, is somewhat rebellious to treatment, and displays a tendency to relapse. [Illustration: Fig. 52. Moist Papules. (_After Miller._)] #How would you distinguish the small-papular syphiloderm from keratosis pilaris, psoriasis punctata, papular eczema, and lichen ruber?# The distribution and extent of the eruption, the color, the grouping, with usually the presence of pustules and large papules and other concomitant symptoms of syphilis, are points of difference. Pustules never occur in the several diseases named, except in eczema. #Describe the large-papular eruption of syphilis.# The _large-papular syphiloderm_ (or _lenticular syphiloderm_) is a common form of cutaneous syphilis, appearing usually in the first six or eight months, and consists of a more or less generalized eruption of pea- to dime-sized or larger, flat, rounded or oval, firmly seated, more or less raised, dull-red papules; with at first a smooth surface, which later usually becomes covered with a film of exfoliating epidermis. The papules, as a rule, develop slowly, remain stationary several weeks or a few months, and then pass away by absorption, leaving slight pigmentation, which gradually fades; or they may undergo certain modifications. In most cases it responds rapidly to treatment. [Illustration: Small-papular Syphiloderm.] [Illustration: Fig. 53. Palmar Syphiloderm.] #What modifications do the papules of the large-papular syphiloderm sometimes undergo?# They may change into the moist papule and squamous papule. #Describe the moist papule of syphilis.#