Pityriasis Rubra Pilaris - Causes, Symptoms, Diagnosis, and Treatment

Introduction

Pityriasis rubra pilaris, or PRP, is a rare inflammatory disorder affecting children and adults. The exact cause for the occurrence of pityriasis rubra pilaris or PRP is unknown. Pityriasis rubra pilaris or PRP is an inflammatory and papulosquamous disorder characterized as a distinct, demarcated plaque of reddish-orange color. Pityriasis rubra pilaris, or PRP, has several subtypes with variable features. The unique symptom of pityriasis rubra pilaris or PRP is the “island of spring,” which denotes the intervening unaffected skin.

What Is Pityriasis Rubra Pilaris?

Pityriasis rubra pilaris, or PRP, is a rare dermatological disorder caused due to unknown etiology. The characteristic feature of pityriasis rubra pilaris or PRP is the intervened unaffected skin known as the “island of spring.” The pityriasis rubra pilaris has no gender predilection. It is observed that the pityriasis rubra pilaris or PRP has a bimodal age distribution which is observed during childhood and adolescence. Many cases of pityriasis rubra pilaris are familial and have autosomal recessive patterns. The pityriasis rubra pilaris, or PRP, is a self-limiting condition and asymptomatic condition.

What Are the Types of Pityriasis Rubra Pilaris?

Pityriasis rubra pilaris, or PRP, has six subtypes with a striking variation. The widely accepted classification of pityriasis rubra pilaris or PRP was proposed by Griffiths in 1980. Based on the age of onset, distribution of lesion, prognosis, and association with human immunodeficiency syndrome or HIV, pityriasis rubra pilaris or PRP has six distinct subtypes.

The subtypes of pityriasis rubra pilaris are mentioned below:

Type 1: Classical adult-onset pityriasis rubra pilaris or PRP.

Type 2: Atypical adult-onset pityriasis rubra pilaris or PRP.

Type 3: Classical juvenile-onset pityriasis rubra pilaris or PRP.

Type 4: Circumscribed juvenile-onset pityriasis rubra pilaris or PRP.

Type 5: Atypical juvenile-onset pityriasis rubra pilaris or PRP.

Type 6: Human immunodeficiency virus or HIV-associated pityriasis rubra pilaris or PRP.

What Are the Clinical Features of Pityriasis Rubra Pilaris?

Variations in color of the papules, plaques, hyperkeratotic follicular papules, and palmoplantar hyperkeratosis are seen across the subtypes of pityriasis rubra pilaris or PRP. The pityriasis rubra pilaris is usually asymptomatic, but mild pruritus is observed in some patients.

The clinical features of pityriasis rubra pilaris or PRP in each type of this condition are mentioned below.

1) Type 1 or Classical Adult-Onset Pityriasis Rubra Pilaris:

This variant is most common in adults. The distinguishing features of classical adult-onset pityriasis rubra pilaris or PRP include red orange-hued papules, plagues with intervened unaffected area, perifollicular keratotic papules, and waxy “sandal-like” palmoplantar keratoderma.

• Follicular-based papules are described as “nutmeg grater” or “exaggerated gooseflesh.”

• A self-limiting variant of pityriasis rubra pilaris.

• The prognosis for this type is good.

• Signs are observed in the scalp, which includes scaly erythema, redness, solitary macule, and follicular papules present in fingers. Other areas involved are the head and neck.

2) Type 2 or Atypical Adult-Onset Pityriasis Rubra Pilaris :

An atypical adult variant of pityriasis rubra pilaris or PRP is present in middle-aged adults, and the clinical findings include skin eczema and ichthyosis in the lower extremities. The common feature of this variant is alopecia.

3) Type 3 or Classical Juvenile-Onset Pityriasis Rubra Pilaris:

It is a classic juvenile pityriasis rubra pilaris, or PRP, observed in children and adults. The clinical features of type1 are seen in this type of variant.

4) Type 4 or Circumscribed Juvenile-Onset Pityriasis Rubra Pilaris:

It is a focal variant of pityriasis rubra pilaris or PRP, which is seen in prepubertal children.

• Clinical features include follicular papules seen in groups with sharp demarcation and erythematous.

• Involved sites have elbows, knees, and bony prominences.

5) Type 5 or Atypical Juvenile-Onset Pityriasis Rubra Pilaris:

It is an atypical generalized juvenile variant of pityriasis rubra pilaris or PRP, and this type of variant is an unremitting hereditary variant.

• Clinical features are similar to the type 3 variant of pityriasis rubra pilaris with the addition of changes like scleroderma.

• The involved site is palms and soles.

6) Type 6 or Human Immunodeficiency Virus or HIV-Associated Pityriasis Rubra Pilaris:

Pityriasis rubra pilaris in human immunodeficiency virus or HIV is type 6 pityriasis rubra pilaris or PRP, and the features are the same as type 1 pityriasis rubra pilaris or PRP.

• The complicated feature of this type of variant is erythroderma.

• Other additional features of this type of variant include hidradenitis suppurativa and acne conglobata.

• The prognosis for this type of variant is poor.

How to Diagnose Pityriasis Rubra Pilaris?

Pityriasis rubra pilaris, or PRP, is usually diagnosed with clinical examination and histopathological findings obtained from biopsies. Other findings like blood examination and immunohistochemical are understudies to assist in the diagnosis of pityriasis rubra pilaris or PRP.

What Is the Differential Diagnosis of Pityriasis Rubra Pilaris?

The variants of pityriasis rubra pilaris should be distinguished from the other papulosquamous disorders. The signs and symptoms of pityriasis rubra pilaris in various combinations should be differentiated.

The differential diagnosis of pityriasis rubra pilaris or PRP is pointed out below:

• Seborrheic dermatitis.

• Psoriasis.

• Acquired and congenital ichthyosis.

• Hereditary palmoplantar keratoderma.

• Erythrokeratodermia.

• Nail changes.

• Erythroderma.

• Atopic dermatitis.

• Cutaneous T-cell lymphoma.

• Congenital ichthyosis.

• Paraneoplastic syndrome.

• Graft versus host disease.

• Lichen spinulosus.

• Keratosis pilaris.

What Is the Treatment of Pityriasis Rubra Pilaris?

Pityriasis rubra pilaris, or PRP, is usually asymptomatic as a self-limiting condition. Treatment includes combination therapy. The inflammation can be reduced with systemic management. Topical therapy, along with systemic management, has beneficial effects.

The various treatment methods for treating pityriasis rubra pilaris are mentioned below:

Topical therapy for pityriasis rubra pilaris includes:

• Emollients.

• Keratolytic agents include urea, salicylic acid, and alpha-hydroxy acid.

• Topical corticosteroids.

• Tazarotene.

• Topical calcineurin inhibitors.

• Oral retinoids for children.

• Methotrexate in combination with oral retinoids.

• Immunosuppressive agents such as tumor necrotizing factor of TNF - alpha inhibitors.

• Secukinumab.

• Ustekinumab.

• Phototherapy includes ultraviolet B, UVB, ultravioletA1 or UVA1 or PUVA, or psoralen ultraviolet A.

Conclusion

Pityriasis rubra pilaris, or PRP, is a rare inflammatory and papulosquamous skin disorder affecting children and adults. The cause of pityriasis rubra pilaris or PRP is unknown, and the incidence of pityriasis rubra pilaris or PRP has no gender predilection. The hallmark sign of pityriasis rubra pilaris is the “island of spring,” which denotes the natural skin. The pityriasis rubra pilaris or PRP is commonly seen in the scalp, fingernails, head, and neck region. Usually, the pityriasis rubra pilaris or PRP is an asymptomatic condition and self-limiting. The prognosis is good in most pityriasis rubra pilaris or PRP variants. In severe cases, the doctor advised combination therapy will improve the condition.