Which physical findings are characteristic of pityriasis lichenoides?

Updated: Sep 11, 2020
  • Author: Jeffrey P Callen, MD; Chief Editor: Dirk M Elston, MD  more...
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The clinical presentation of Mucha-Habermann disease spans a continuum that is a function of the acuity of onset. PLEVA and PLC are not distinct diseases, but rather, they are different manifestations of the same process, although the process is accelerated in PLEVA.

PLEVA presents acutely with 10-50 erythematous–to–reddish brown or purpuric round or ovoid lichenoid papules that are 5-15 mm in diameter. Many papules demonstrate a pseudovesicular summit evolving to a central necrosis and a hemorrhagic crust. Note the images below.

Typical hemorrhagic crusted papules of pityriasis Typical hemorrhagic crusted papules of pityriasis lichenoides et varioliformis acuta.
Close-up view of typical lesions of pityriasis lic Close-up view of typical lesions of pityriasis lichenoides et varioliformis acuta.

PLC presents as small erythematous–to–reddish brown papules, although with increased numbers compared to PLEVA. A fine scale usually is found, although not initially, which has been likened to frosted glass. The eruption often is polymorphic, with lesions at different stages of evolution. Note the images below.

Scaling papules of pityriasis lichenoides chronica Scaling papules of pityriasis lichenoides chronica.
Close-up view of typical pityriasis lichenoides ch Close-up view of typical pityriasis lichenoides chronica lesions. Note papules in different stages of evolution and the scale with frosted-glass appearance in the lower right-hand corner.

Lesions that are clinically consistent with both PLEVA and PLC often are found on physical examination, and the polymorphic appearance helps distinguish Mucha-Habermann from guttate psoriasis and lichen planus.

PLEVA lesions may evolve into lesions of PLC. Most lesions heal with postinflammatory changes, such as a transient or persistent leukoderma or hyperpigmentation.

Ulceronecrotic PLEVA presents with a sudden eruption of diffuse coalescent necrotic ulcerations associated with high fever. Some lesions may resemble those of PLC, but many are large, ulceronecrotic, and covered by a black oyster shell-like crust. Necrotic ulcerating lesions may eventuate into varioliform scars.

Dark-skinned people rarely may present with widespread macular hypopigmentation rather than the typical papular morphology. [26] This variant is most common in children. The diagnosis depends on careful inspection, which reveals subtle PLC lesions that are compatible histologically with this diagnosis.

In both PLEVA and PLC, lesions are scattered but discrete. Lesions may be distributed symmetrically or asymmetrically on the trunk, buttocks, and proximal extremities, with occasional acral involvement. Lesions may appear on the palms, soles, face, and scalp. Asymmetric or segmental nondermatomal presentations have been reported.

Erosions and hemorrhagic crusts may be found.

Mucosal lesions consisting of irregular erythema and superficial ulcerations on the buccal mucosa and palate have been reported.

Dermoscopic features reported in 2 patients with PLEVA were papules with a central whitish patch or crusted lesions with an amorphous brownish structure, both surrounded by a well-defined ring of pinpoint and/or linear vascular structures with a targetoid aspect. [27] A small study in 17 patients found that linear irregular vessels on dermoscopy were significantly associated with PLC over guttate psoriasis. [28]

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