What is Pityriasis Rubra Pilaris

TL;DR: Pityriasis rubra pilaris (PRP) is a rare, chronic inflammatory skin disorder characterized by reddish-orange scaling patches and small, rough bumps around hair follicles. While the exact cause remains unknown, it is considered an immune-mediated condition that can significantly impact a patient’s quality of life and skin barrier function.

What exactly is Pityriasis rubra pilaris?

Pityriasis rubra pilaris is a rare papulosquamous skin disease. It is clinically recognized by the presence of follicular hyperkeratosis (small, rough bumps resembling "goosebumps" that feel like a nutmeg grater) and distinct, salmon-colored or reddish-orange plaques. Unlike some other skin conditions, Pityriasis rubra pilaris often presents with "islands of sparing," which are patches of perfectly healthy skin surrounded by the characteristic redness. It is a chronic condition, meaning it persists over time, though the severity can fluctuate significantly.

Which body systems are affected by Pityriasis rubra pilaris?

The primary system affected is the integumentary system (the skin). However, because the skin barrier is compromised, patients often experience systemic discomfort. Common physical manifestations include:

• Palms and soles: Often develop a thick, yellowish, waxy appearance known as palmoplantar keratoderma.


• Hair and nails: Nails may become thickened or discolored, and hair loss can occur in some cases.


• Systemic symptoms: While not an internal organ disease, the widespread skin inflammation can lead to heat loss, shivering, and significant discomfort.

How is Pityriasis rubra pilaris classified?

Dermatologists typically use the Griffith classification system to categorize Pityriasis rubra pilaris into six distinct types based on age of onset, clinical presentation, and prognosis:

1. Type I (Classic Adult): The most common form, typically clearing within 1–3 years.


2. Type II (Atypical Adult): A chronic form that may last for decades.


3. Type III (Classic Juvenile): Similar to Type I but occurs in children.


4. Type IV (Circumscribed Juvenile): Limited to specific areas like knees and elbows.


5. Type V (Atypical Juvenile): Often present from early childhood and may have a genetic component.


6. Type VI (HIV-associated): Linked to underlying HIV infection.

Who is typically affected by this condition?

Pityriasis rubra pilaris is considered quite rare, with an estimated prevalence ranging from 1 in 3,500 to 1 in 50,000 dermatology patients. It affects both males and females equally and occurs across all ethnic groups. While it can appear at any age, there are two peak periods of onset: the first two decades of life and the fifth to sixth decades. Currently, 96 people with Pityriasis rubra pilaris have joined the DiseaseMaps community to share their personal experiences and support one another.

What differentiates Pityriasis rubra pilaris from other conditions?

It is frequently misdiagnosed as psoriasis because both conditions involve red, scaly skin. However, Pityriasis rubra pilaris is distinct due to the specific reddish-orange hue of the lesions, the follicular bumps, and the "islands of sparing." Genetic research has identified mutations in the CARD14 gene in some familial cases of Pityriasis rubra pilaris, which helps researchers distinguish it from plaque psoriasis on a molecular level.

Next steps

• Consult a board-certified dermatologist who has experience managing rare inflammatory dermatoses.


• Consider a skin biopsy to confirm the diagnosis and rule out other conditions like psoriasis or pityriasis lichenoides.


• Join the DiseaseMaps community to connect with other patients who understand the daily challenges of living with this condition.


• Keep a symptom diary to track potential triggers, such as stress, weather changes, or infections.

Medical disclaimer: This information is for educational purposes only and does not constitute medical advice, diagnosis, or treatment; always seek the advice of your physician with any questions regarding a medical condition.

References

• Orphanet: Pityriasis rubra pilaris (ORPHA:2910)


• NIH Genetic and Rare Diseases Information Center (GARD): Pityriasis rubra pilaris


• OMIM (Online Mendelian Inheritance in Man): Pityriasis rubra pilaris; PRP


• Journal of the American Academy of Dermatology: Review of clinical features and management of PRP