Pityriasis rosea is a for the use ...

Pityriasis rosea is a for the use of all skin condition characterized by a herald patch and the later appearance of lesions arrayed along Langer's lines (cleavage lines). The condition is diagnosed greatest in number often in children and young adults. Several large case series from dermatology practices indicate that the incidence of pityriasis rosea peaks in individuals 20 to 29 years of age, with no consistent form relative to sex predilection (Table 1). (1-3)

Etiology

Although the etiology of pityriasis rosea is unclear, several factors indicate an infectious cause. First, outbreaks of the condition be found in clusters, suggesting that an infectious agent is circulating within a community. (4) secondary recurrence of pityriasis rosea outside the acute phase is rare, suggesting that there is long-lasting immunity after the infection. Third, up to 69 percent of patients with pityriasis rosea have a prodromal illness before the herald patch appears. (5) Finally, near patients with pityriasis rosea present to view an increase in B lymphocyte a decrease in T lymphocyte and an elevated sedimentation rate. (6)

Unfortunately, on a level though electron microscopy shows any viral changes and possible viral particles, antibody and polymerase chain reaction proofs for known viruses have failed to identify an offending virus. The proceeds of one study (7) showed elevated plains of human herpesvirus 7 in patients with pityriasis rosea. However, after study results (6,8,9) showed no consistent increase of human herpesvirus 7 flats in affected patients compared with rule patients. Furthermore, human herpesvirus 7 infection is general in childhood, and the virus is inclined to reactivation. Several other viruses have been examined, however none has been found to be causative. (6)

Chlamydia pneumoniae, Legionella pneumophila, and Mycoplasma pneumoniae also have been glance ated as potential infectious agents in pityriasis rosea. However, the be the effects of a small prospective case-control inquiry (10) did not show a significant rise in antibodies to these bacteria when affected patients were compared with matched direct patients.

Diagnosis

Identification of pityriasis rosea can be challenging for a number of reasons. The diagnosis is unclear at the attack of symptoms, and there are no noninvasive ordeals that confirm the condition. In at least individual half of patients, the first symptoms of pityriasis rosea are nonspecific and consistent with a viral upper respiratory infection. (15) A herald patch then appears, typically onward the trunk. This large lesion is commonly 2 to 10 cm in diameter, ovoid, erythematous, and slightly raised, with a typical collarette of scale at the margin (Figure 1) At this stage, however, the diagnosis usually remains unclear. Microscopic examination of potassium hydroxide preparations exhibit tos no fungal elements. The lesion cannot be differentiated from eczema and many times is treated as such.

[FIGURE 1 OMITTED]

A scarcely any days to a few weeks after the appearance of the herald patch, first stomachs of smaller lesions, 5 to 10 mm in diameter, cause to grow across the trunk and, les commonly forward the extremities. These lesions are salmon colored, ovoid, raised, and have the same collarette of scale as the herald patch (Figure 2) At this stage, the diagnosis usually is clear, particularly if the physician can see or elicit a history of the herald patch.

[FIGURE 2 OMITTED]

If the diagnosis is uncertain, especially if the palms and individuals are affected and the patient is sexually active, the physician should consider the possibility of secondary syphilis. Appropriate evaluation includes direct fluorescent antibody testing of lesion exudates, a VDRL trial or dark-field microscopy. (11) Other conditions in the differential diagnosis include diffuse nummular eczema, tinea corporis, pityriasis lichenoides, guttate psoriasis, viral exanthem, lichen planus, and medication reaction.

The smaller secondary lesions of pityriasis rosea come [i]or[/i] go after [i]or[/i] behind Langer's lines (Figure 3). When the lesions present itself on the back, they align in a typical "Christmas tree" or "fir tree" pattern. Elsewhere onward the body, the lesions go after the cleavage lines as follows: transversely across the lower abdomen and back, circumferentially around the shoulders, and in a V-shaped pattern in succession the upper chest (12) (Figure 4) Pruritus is variable. leave out for mild to severe itching in 25 percent of patients, no systemic symptoms typically are at hand during the rash phase of pityriasis rosea.

[FIGURE 3 OMITTED]

Pityriasis rosea can meet the eye in an inverse form in which the extremities are affected if it were not that the trunk is spared (Figure 5) Les commonly pityriasis rosea be met withs in a localized form, which makes the diagnosis more difficult. Gigantean (larger and fewer lesions), pustular, purpuric, or vesicular pityriasis rosea come into one's heads in rare cases. (13) At times, no herald patch is fix In one series, (3) no other than 17 percent of patients referr to a dermatology clinic reported a herald patch; absence of a herald patch made the diagnosis more difficult and necessitated referral.