SD of the scalp, face, and ears may be clinically and microscopically indistinguishable from PV. Biopsy is often of no value because at this point both diseases can show similar findings. Family history and follow-up will usually separate the two. The lesions of PV develop a deeper color, are more raised, and develop a silvery rather than yellow scale. In addition, PV lesions tend to be more fixed and circumscribed than SD lesions. In the absence of other lesions, the presence of linear nail pitting points to a diagnosis of PV.
Eruptive PV in its early stages can be indistinguishable from early PR. This diagnosis must always be considered in a patient with a positive family history for PV. In general, PV will progress unless treated, and as the lesions mature they develop the deeper color and loose silvery scale typical of that disease. Eruptive PV should always be considered with fixed PR. Usually PV lacks a herald plaque and the classic Christmas tree pattern. At this stage, the biopsy findings are generally inconclusive. A short period of observation will usually spare the victim the discomfort, scar, and expense of biopsy. As with SD, the presence of nail pitting favors a diagnosis of psoriasis.
The resemblance is usually superficial. Lesions of PV tend to be more profuse and more symmetrical than those of nummular eczema. Scale of PV is also more prominent, loose, and silvery. Eczema lesions are often moist and the scale has a crackled or fissured pattern. Itching can occur in both diseases but is usually intense with nummular eczema.
Secondary papulosquamous syphilis can closely resemble eruptive guttate PV. Patients with syphilis usually have associated constitutional symptoms of fatigue, fever, and myalgias. In addition, there are often palmar lesions, mucous membrane lesions, and generalized lymphadenopathy. A syphilis serology with the same precautions regarding prozone effect is definitive.
Discoid and subacute lupus erythematosus (LE) can occasionally resemble PV in onset, distribution, and lesional morphology. Lupus lesions usually have a deeper hue with telangectasias. Scarring, which is absent in psoriasis, tends to occur early in discoid LE. Arthralgias and systemic symptoms may be present, especially with subacute LE. When suspected, a skin biopsy is helpful along with an antinuclear, anti-Ro (SS-A), and anti-La (SS-B) antibodies.
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Do You Suffer From the Itching and Scaling of Psoriasis? Or the Chronic Agony of Psoriatic Arthritis? If so you are not ALONE! A whopping three percent of the world’s populations suffer from either condition! An incredible 56 million working hours are lost every year by psoriasis sufferers according to the National Psoriasis Foundation.