A very uncommon skin condition called pityriasis lichenoides is typified by the appearance of tiny, scaling papules that can be pink, red, or brownish in hue.   

There are two primary forms which are as follows: 

Pityriasis Lichenoides Chronica (PLC): This type of the disease is typified by the recurrent tiny reddish-brown papules that can crust over and leave a brown stain behind when they heal. Crops may develop lesions that are slightly irritating.  

Pityriasis Lichenoides Et Varioliformis Acuta (PLEVA): This type mimics chickenpox lesions and is typified by more severe, acute eruptions with larger, redder papules.

17 cases of PLEVA were identified out of 44,000 patients visited over a ten-year period in three catchment areas in Great Britain. 

Every race is impacted. There has been no mention of a racial tendency. There have been reports of a male predominance in the pediatric population.

It is postulated that PL could be the consequence of an aberrant immunological reaction, potentially involving T-cells. Pityriasis lichenoides lesions have been studied using immunohistochemistry, which has revealed a lymphocyte infiltration into the damaged skin, mostly CD4+ T-cells.  

Despite reports of immunoglobulin and complement deposition in vessels, Mucha-Habermann illness is not a vasculitic condition. There is no thrombi in the lumen and no fibrin in the vessel walls. 

The cause of PLC and PLEVA is still unknown in many cases without a clear culprit being found.  

All Grade or self-limited lymphoproliferative disease, an infectious agent response, or an inflammatory reaction to an unidentified epitope have all been considered. 

The prognosis can be affected by the PL subtype. With frequent flare-ups over an extended period, pityriasis lichenoides chronica (PLC), characterized by persistent, tiny, scaling papules, tends to have a more chronic course.   

The prognosis may be impacted by the intensity of symptoms, which includes the degree of skin involvement, the existence of itching, pain, or other discomfort. More active therapy and monitoring may be necessary in severe cases of PL with widespread or incapacitating symptoms.

Age Group:  

Pityriasis lichenoides can affect individuals of any age, but it is most seen in children and young adults. The peak age of onset is typically between 5 and 15 years old.  

Associated Comorbidity or Activity:   

PL has been reported in association with various immunodeficiency disorders, such as human immunodeficiency virus (HIV) infection, common variable immunodeficiency (CVID), and other primary immunodeficiencies.  

There have been reports of PL occurring in association with autoimmune diseases, such as systemic lupus erythematosus (SLE), rheumatoid arthritis, and autoimmune thyroid disorders. 

Acuity of Presentation:  

PLC typically presents with a more indolent and chronic course. The lesions of PLC are characterized by small, scaling papules that may be pink, red, or brownish in colour. These papules can persist for weeks to months and may come and go over an extended period.  

PLC lesions are usually asymptomatic or mildly pruritic (itchy), and they tend to resolve spontaneously without scarring. The chronic nature of PLC distinguishes it from the more acute presentation of pityriasis lichenoides et varioliformis acuta (PLEVA). 

• Distribution of Lesions: The distribution of lesions can provide important diagnostic clues. In PLC, the lesions are often distributed symmetrically on the trunk and proximal extremities, with a tendency to spare the face and palms/soles.  
• Characteristics of Lesions: Lesions in PL may evolve over time. In PLC, the papules may become crusted or hyperpigmented as they resolve. In PLEVA, the lesions may progress to vesicles, pustules, or ulcers, with subsequent crusting and healing. 
• Associated Symptoms: Patients with PL may experience associated symptoms such as itching (pruritus), pain, or discomfort.

• Pityriasis Lichenoides is typically not associated with specific comorbidities. It can occur in otherwise healthy individuals. However, in some cases, there may be a history of recent infections or the use of certain medications, which could be potential triggers. Infections, wildly viral and bacterial infections, have been linked to the development of Pityriasis Lichenoides. Additionally, certain medications, such as antibiotics, antimalarials, and TNF-alpha inhibitors, have been reported to be associated with the onset of the condition in some individuals.

There are two primary clinical forms of Pityriasis Lichenoides, each with a different acuity of presentation:

• Pityriasis lichenoides Chronica (PLC): PLC is the chronic form of the condition. The lesions in PLC are small, reddish-brown, scaly papules that typically develop over several weeks to months. The lesions may be recurrent and persist for an extended period, sometimes even for years. PLC is generally milder in terms of symptoms and discomfort.
• Pityriasis Lichenoides et Varioliformis Acuta (PLEVA): PLEVA is the acute form of Pityriasis Lichenoides. It is characterized by the sudden onset of more pronounced symptoms. The lesions in PLEVA are often larger, erythematous (red), and may have central vesicles that can ulcerate and crust over. PLEVA lesions are more likely associated with itching, pain, and discomfort. The course of PLEVA is usually more rapid, with lesions resolving over weeks to months.

• Topical Corticosteroids: Topical corticosteroids are commonly used to reduce inflammation and itching associated with PL lesions. Low to mid-potency topical corticosteroids may be applied to affected areas once or twice daily. 
• Phototherapy: Phototherapy, including narrowband ultraviolet B (UVB) therapy or psoralen plus ultraviolet A (PUVA) therapy, may be effective in reducing inflammation and promoting resolution of PL lesions, especially in cases of more severe or refractory disease. 
• Systemic Treatments: In cases of severe or widespread PL, systemic treatments such as oral antibiotics, oral corticosteroids, or oral retinoids may be considered. 

Dermatology, General

• Avoidance of Irritants: Certain environmental irritants, such as harsh soaps, detergents, fragrances, and abrasive fabrics, can exacerbate skin inflammation and irritation in individuals with PL. 
• Sun Protection: Sun exposure can sometimes worsen PL lesions or trigger flare-ups. Recommending sun protection measures, such as wearing protective clothing, using broad-spectrum sunscreen with a high sun protection factor (SPF), and avoiding prolonged sun exposure, especially during peak sunlight hours, may help reduce the risk of exacerbating PL lesions. 
• Stress Management: Stress is known to exacerbate various skin conditions, including PL. Encouraging stress management techniques, such as relaxation exercises, mindfulness meditation, yoga, or counseling, may help reduce stress levels. 
• Avoidance of Trauma to Skin: Trauma or friction to the skin can exacerbate PL lesions and lead to Koebnerization, where new lesions develop at the site of injury. 

Dermatology, General

• Tetracycline: It has broad-spectrum antibacterial activity and can effectively target and eliminate bacteria that may colonize PL lesions. By reducing bacterial load, it may help to alleviate inflammation and promote resolution of lesions. Tetracycline antibiotics have been shown to possess anti-inflammatory properties, including inhibition of pro-inflammatory cytokines and modulation of immune responses.  

Dermatology, General

• Methoxsalen: It is a photosensitizing agent that increases the skin’s sensitivity to ultraviolet A (UVA) radiation. When administered orally or topically, methoxsalen is absorbed by the skin and accumulates in PL lesions.  Upon exposure to UVA radiation, methoxsalen interacts with DNA and forms cross-links, which can lead to cell death and suppression of immune responses in the skin. 

Dermatology, General

• Acitretin: They shows anti-inflammatory properties, including inhibition of pro-inflammatory cytokines and modulation of immune responses in the skin.  By suppressing inflammation, acitretin can help alleviate itching, erythema (redness), and other symptoms associated with PL. 

Dermatology, General

• Methotrexate: It suppresses the immune response by inhibiting the proliferation of T lymphocytes and other immune cells involved in the inflammatory cascade.  Methotrexate can alleviate symptoms such as itching, erythema (redness), and scaling associated with PL lesions. 

Dermatology, General

• Phototherapy: Phototherapy involves exposing the affected skin to ultraviolet (UV) light to reduce inflammation and promote healing. Narrowband ultraviolet B (UVB) therapy and psoralen plus ultraviolet A (PUVA) therapy are two common types of phototherapies used in the treatment of PL.  UVB therapy utilizes a specific wavelength of UV light to target inflammatory cells in the skin, while PUVA therapy involves combining oral or topical psoralen with UVA light exposure.  

Dermatology, General

• Assessment and Diagnosis: The initial phase involves obtaining a detailed medical history and conducting a thorough physical examination to assess the extent and severity of PL lesions. 
• Acute Management: In the acute phase of management, the focus is on symptomatic relief and reducing inflammation. Topical corticosteroids, topical calcineurin inhibitors, or oral antihistamines may be prescribed to alleviate itching and discomfort associated with PL lesions. 
• Maintenance Therapy: Maintenance therapy may involve the use of topical corticosteroids or calcineurin inhibitors on an intermittent basis to keep PL lesions under control. 
• Monitoring and Follow-Up: Regular monitoring and follow-up appointments are essential throughout the management of PL to assess treatment response, monitor for adverse effects, and adjust management strategies as needed.