What Is Pityriasis Rosea

Introduction

Pityriasis rosea is a common skin ailment characterized by a rash of raised, red, scaly spots all over the body. It can affect anyone, although older children and young adults (ages 10 to 35) are more likely to be affected.¹ It is frequently distinguished by an initial herald patch, which is followed by scaly oval patches within 2 weeks. The herald patch, on the other hand, is not always present. On the trunk and proximal extremities, the scaly oval patches generally form a Christmas tree pattern.²

Etiology and causes

1. Potential viral triggers (e.g., herpesvirus): Some studies have implicated that the Human Herpes Viruses 6 and 7 can cause pityriasis rosea.³
2. Immune response connection: Some patients also show an increase in B lymphocytes and a decrease in T lymphocytes, along with an increase in Erythrocyte sedimentation rate (ESR). Lymphocytes are white blood cells that fight against infections, so their rise is also significant. In addition, many infections show a rise in the ESR.³
3. Vaccinations: Pityriasis rosea-like eruptions have been described following vaccinations such as BCG, influenza, H1N1, diphtheria, smallpox, hepatitis B, and pneumococcus.²
4. Drug-induced pityriasis rosea: Drugs such as barbiturates (sedatives), bismuth, captopril (used to treat high blood pressure), gold (used to treat rheumatoid arthritis), metronidazole (antibiotic), D-penicillamine (chelating agent used in some poisonings), and isotretinoin (anti-ageing skin treatment) have also been linked to outbreaks.³

Clinical presentation

Herald patch

A single pink or red oval patch of scaly skin known as the "herald patch" normally emerges at least 2 days before a more widespread rash appears. The size of the herald patch varies from 2cm to 10cm. It can appear on your abdomen, chest, back, or neck, as well as on your face, scalp, or near your genitals, although this is less frequently seen.⁴

Secondary rash

• A more widespread rash may occur up to 2 weeks after the herald patch emerges and may expand over the next 2 to 6 weeks.
• This rash appears as tiny, raised, scaly spots up to 1.5cm in size. The majority of people get several patches on their chest, back, tummy, neck, upper arms, and upper thighs. The face is rarely impacted.
• Although the rash is not unpleasant, it can be annoying.
• The spots are frequently pinkish-red in people with fair complexion. Patches on people with dark complexion might be grey, dark brown, or black.
• The herald patch and rash typically persist for 2 to 12 weeks; however, they can last up to 5 months.
• You may have some darker or brighter spots of skin after the rash has gone away. These should resolve within a few months and will not result in permanent scarring.¹

Diagnosis

Clinical evaluation

Typically, the condition begins with a single, primary 2- to 10-cm herald patch on the trunk or proximal limbs. A general centripetal eruption of 0.5- to 2-cm rose- or fawn-coloured oval papules and plaques appear within 7 to 14 days. Distinguishing pityriasis rosea (PR) from other skin conditions involves recognizing its characteristic features and differentiating them from similar presentations. Here are the key distinguishing features of PR from other skin conditions:

• One of the hallmark features of PR is the presence of a single larger patch known as the "herald patch."
• As PR progresses, smaller pink or red oval-shaped lesions develop on the trunk and limbs, creating a distinct "Christmas tree" or "fir tree" pattern. This pattern emerges due to the arrangement of the lesions along the lines of skin tension (Langer's lines).
• Lesions in PR tend to appear symmetrically on the body.
• The lesions in PR often exhibit collarette scaling, where the edges of the lesions have a thin, raised, and slightly scaly border that gives the appearance of a collar.
• PR is self-limiting and typically resolves on its own without leaving any significant scarring or pigmentation changes.
• PR lesions can be pruritic (itchy), but the degree of itchiness can vary among individuals. The itchiness is often milder compared to certain other skin conditions characterized by intense itching, like scabies.
• Unlike ringworm (tinea corporis) or other fungal infections, PR lesions do not have a central clearing. This is particularly important in differentiating it from tinea infections.
• PR lesions are generally not annular (ring-shaped), which helps distinguish them from conditions like ringworm or erythema migrans (associated with Lyme disease).
• The lesions in PR tend to evolve over time, with newer lesions developing and older ones fading. This dynamic process of lesion evolution is characteristic of PR.
• PR lesions are usually flat or slightly raised, and they do not contain vesicles (fluid-filled blisters) or pustules (pus-filled lesions), which are seen in conditions like herpes simplex or impetigo.
• While PR lesions can appear anywhere on the body, they are commonly found on the trunk, upper arms, thighs, and neck. This distribution can help distinguish PR from conditions with different predilection sites. Top of Form.⁵

Differential diagnosis

1. Tinea infections: Tinea infections often present as round or oval-shaped red or pink patches with a raised and slightly scaly border. They have a central clearing, resulting in a ring-like appearance. Lesions in tinea infections can also spread, resulting in distinct rings. Tinea infections are often associated with more intense itching. Tinea infections can occur on various parts of the body, including the trunk, limbs, and face.⁶
2. Psoriasis: Psoriasis often presents as raised, red, well-defined patches with thick silvery-white scales. These patches can be of various sizes and shapes and are commonly found on the scalp, elbows, knees, and lower back. Psoriasis plaques tend to persist for longer periods, often without the rapid evolution seen in PR lesions. Psoriasis is often associated with more significant itching and discomfort. Psoriasis has a genetic component, and a family history of psoriasis could provide additional clues for diagnosis.⁷
3. Secondary syphilis: Secondary syphilis typically presents with a diffuse rash that may involve the trunk, palms, and soles. The rash can be maculopapular (flat and raised), but it's generally not as distinctly patterned as in PR. The rash in secondary syphilis can vary widely, but lesions are more likely to be raised and may have a coppery-red colour. They can also be flat, scaly, or even pustular. Mucous membrane lesions (mucous patches) can also be present. PR lesions tend to evolve over a few weeks, whereas secondary syphilis lesions can appear a few weeks- months after the primary syphilis infection.⁸
4. Drug reactions: The onset of a drug-induced rash is closely related to the initiation of the medication. It may develop within days to weeks after starting the medication. New medications, especially those started shortly before the rash appeared, need to be carefully evaluated as potential triggers. Drug-induced rashes can vary widely in appearance, from maculopapular to urticarial, vesicular, or even bullous. The appearance may not be as consistent as in PR.⁹

Epidemiology

The prevalence of pityriasis rosea is estimated to be 0.5% to 2%. It affects people of both genders, most of whom are between the ages of 15 and 30, but it also affects elderly adults and children. Seasonal changes can affect their prevalence, where PR is more prevalent in the spring and fall.¹⁰ In the United States, the estimated prevalence of pityriasis rosea is 0.13% in females and 0.14% in males, with a 0.3-3% prevalence at dermatology centres.¹¹

Treatment and management

1. Self-Care and Symptom Relief:
   • Hygiene: Maintain good hygiene by regularly cleansing the affected area with mild soap and water to prevent bacterial infections.
   • Moisturization: Apply unscented moisturizers to alleviate itching and dryness.
   • Applying cool compresses or taking chilly baths might help relieve itching and reduce inflammation.
2. Over-the-Counter Medications:
   • Topical Steroids: Over-the-counter (OTC) hydrocortisone creams can help relieve itching and inflammation. However, use these sparingly and only as directed, as prolonged use of topical steroids can have side effects.
3. Prescription Medications:
   • Oral Antihistamines: Prescription-strength antihistamines can help manage itching and promote better sleep. Your doctor will determine the appropriate dosage and medication based on your needs.
   • Topical Steroids: For severe itching and inflammation, your doctor may prescribe stronger topical steroids.
   • Sun Exposure: Some individuals find that moderate sun exposure can help alleviate symptoms and speed up the healing process. However, be cautious and use sunscreen to prevent excessive sun damage.
4. Avoid Triggers:
   • Certain factors like stress, excessive sweating, and certain fabrics can exacerbate symptoms. Attempt to recognize and avoid these triggers.
5. Diet and Lifestyle:
   • A vitamin and nutrient-rich diet can help with general skin health. Staying hydrated and managing stress can also contribute to symptom relief.
6. Phototherapy:
   • In some cases, controlled exposure to ultraviolet (UV) light under medical supervision can help alleviate symptoms. This is typically done with narrowband UVB phototherapy.
7. Prescription Medications:
   • In rare cases, when symptoms are severe or persistent, a doctor might prescribe oral corticosteroids, antiviral medications, or other immune-modulating drugs.¹²

Patient education- tips for managing

• Try to avoid overheating. Heat might aggravate the redness and itching.
• Avoid heated temperatures wherever feasible to avoid the danger of overheating.
• While you have the rash, avoid intense activities.
• Avoid using hot tubs and whirlpools.
• Showers, baths, and skin care products might cause discomfort.
• Hot water and harsh soaps might aggravate the redness and itching. If your rash does not itch, a hot shower or the use of a powerful soap can cause it to itch.¹³

Conclusion

• Pityriasis rosea is a distinctive and benign skin condition that presents with a characteristic pattern of skin lesions. Whilst its exact cause remains uncertain, the condition is believed to have viral origins and is often self-limiting. Pityriasis rosea begins with a single larger patch known as the "herald patch," followed by smaller oval lesions that form a unique "Christmas tree" distribution on the trunk and limbs.
• Though it can be mildly itchy, the itchiness is generally less intense compared to other skin conditions. With no clear association to recent medication use and no systemic symptoms, pityriasis rosea's primary focus is on its distinct dermatological presentation. It's essential to differentiate pityriasis rosea from other skin conditions with similar features, such as tinea infections, psoriasis, secondary syphilis, and drug reactions.
• Clinical examination, lesion appearance, distribution, patient history, and sometimes additional tests such as biopsies or serological tests play crucial roles in accurate diagnosis. While treatment for pityriasis rosea is mainly aimed at symptom relief, understanding the condition's self-limiting nature and ensuring proper patient education regarding its course and management is vital.