Summary about Disease
Pityriasis lichenoides (PL) is a rare inflammatory skin disease characterized by the eruption of small, scaly papules that evolve through different stages. There are two main forms: pityriasis lichenoides et varioliformis acuta (PLEVA), which is more acute and severe, and pityriasis lichenoides chronica (PLC), which is milder and more persistent. While the exact cause remains unknown, PL is thought to be related to an abnormal immune response. It is not contagious.
Symptoms
PLEVA: Characterized by crops of small, red or brownish papules that may become vesicular (blister-like) or pustular (pus-filled). These lesions often ulcerate or form crusts before healing. Lesions can be itchy or even painful.
PLC: Presents with smaller, flatter, scaly papules that are typically less inflamed than PLEVA lesions. Scale is often mica-like, lesions are typically not painful. Both forms can present with lesions on the trunk, arms, legs, and sometimes the face and scalp. Lesions can be present at various stages of development simultaneously.
Causes
The exact cause of pityriasis lichenoides is unknown. Current theories suggest it's an immune dysregulation, possibly triggered by an infection (e.g., parvovirus B19, toxoplasmosis, Epstein-Barr virus). It is not believed to be a direct infection itself. T-cell abnormalities and a clonal T-cell population may be present in the lesions.
Medicine Used
Treatment varies depending on the severity of the condition. Options include:
Topical corticosteroids: To reduce inflammation and itching.
Topical retinoids: To help normalize skin cell turnover.
Oral antibiotics (tetracycline, erythromycin): Especially for PLEVA, to target potential triggering infections or associated inflammation.
Phototherapy (UVB or PUVA): To suppress the immune response in the skin.
Systemic medications (methotrexate, cyclosporine): Reserved for severe or refractory cases.
Dapsone: In some cases
Is Communicable
No, pityriasis lichenoides is not communicable or contagious. It cannot be spread from person to person.
Precautions
Since the cause is unknown, specific preventative measures are limited. General skin care practices, such as using gentle cleansers and moisturizers, may help manage symptoms. Avoiding known triggers (if any are identified) and protecting skin from excessive sun exposure are also recommended. There are no known strategies to completely prevent outbreaks, however.
How long does an outbreak last?
The duration of pityriasis lichenoides is highly variable.
PLEVA: Tends to be more acute, often resolving within weeks to months. However, recurrences are common.
PLC: Can be more chronic, lasting for months or even years, with periods of improvement and exacerbation. The course of the disease is unpredictable, and some individuals may experience prolonged or recurrent episodes.
How is it diagnosed?
Diagnosis is typically based on clinical examination of the skin lesions. A skin biopsy is often performed to confirm the diagnosis and rule out other conditions. The biopsy will show characteristic inflammatory infiltrates around blood vessels in the dermis and sometimes involvement of the epidermis.
Timeline of Symptoms
The timeline of symptoms varies depending on the subtype:
PLEVA:
Initial phase: Sudden eruption of small, red papules.
Progression: Papules may become vesicular or pustular.
Ulceration/Crusting: Lesions often ulcerate or form crusts.
Healing: Lesions heal, sometimes leaving scars. New crops of lesions may appear.
PLC:
Initial phase: Gradual appearance of small, flat, scaly papules.
Progression: Papules may persist for weeks or months.
Scale formation: Mica-like scale is characteristic.
Resolution: Lesions eventually resolve, but new lesions may continue to appear over time.
Important Considerations
Rule out other conditions: Pityriasis lichenoides can resemble other skin disorders, such as chickenpox, guttate psoriasis, secondary syphilis, or lymphomatoid papulosis. Accurate diagnosis is essential.
Potential association with infections: While not directly caused by infection, potential triggering infections should be considered and investigated.
Lymphomatoid papulosis association: In rare instances, pityriasis lichenoides, especially PLEVA, can be a precursor to or associated with lymphomatoid papulosis (a type of cutaneous T-cell lymphoma). Long-term monitoring may be necessary, particularly in severe or persistent cases.
Impact on Quality of Life: Although not life-threatening, pityriasis lichenoides can significantly affect quality of life due to itching, discomfort, and cosmetic concerns. Psychological support may be helpful for some individuals.