Common Papulosquamous Skin Disorders

Common Papulosquamous Skin Disorders

• Papulosquamous reaction pattern: A common pattern of inflammation in the skin characterized by both papules (small bumps/lesions) and scales.
• Psoriasis: A chronic inflammatory skin condition that affects the skin's growth cycle, leading to scaling, redness, and thickened plaques.
  • Clinical Presentation: Typically, psoriasis presents with well-defined, raised, reddish plaques covered by silvery-white scales.
  • Nail Changes: Nail pitting, onycholysis (nail separation from nail bed), and subungual hyperkeratosis (thickening of the nail bed) are commonly observed.
  • Pathogenesis:
    • T-helper cell (Th) 1 and Th17 immune cells play a crucial role in the development of psoriasis.
    • Abnormal activation of keratinocytes, leading to rapid proliferation.
  • Risk Factors:
    • Genetics: Strong genetic component, with family history being a significant risk factor.
    • Environmental triggers: Trauma, infections, medications, stress, extreme temperatures, and smoking can exacerbate the condition.
  • Diagnosis: Typically based on clinical examination and a patient's history. Biopsy can be used to confirm the diagnosis in challenging cases.
  • Treatment: Treatment primarily focuses on slowing down skin cell growth and reducing inflammation.
    • Topical Treatments: Corticosteroids, calcineurin inhibitors, vitamin D analogs, and salicylic acid are commonly used.
    • Phototherapy: Narrowband UVB phototherapy and PUVA (psoralen plus UVA) are effective treatment options.
    • Systemic Therapy: Methotrexate, cyclosporine, biologics (adalimumab, etanercept, infliximab), and retinoids are used for more severe cases.
  • Prognosis: While psoriasis is a chronic condition, with proper treatment, it can be effectively managed, and periods of remission can be achieved.

Seborrheic Dermatitis

• General Features:

  • Chronic and relapsing skin condition that commonly affects individuals of all ages.

  • Increased incidence in patients older than 50 years.

  • Infantile seborrheic dermatitis peaks at 3 months of age.

  • Male predominance.

  • Seasonal variation: More severe in cold and dry climates, mitigated by sun exposure.

  • Often found in:

    • Nasolabial folds (area around the nose and mouth).
    • Posterior auricle (behind the ear).
    • Eyebrows.

  • Associated with HIV/AIDS:

    • More extensive and refractory patterns in up to 83% of HIV-positive individuals.
    • Often observed in patients undergoing retroviral therapy.
• Clinical Presentation: Characterized by greasy, yellowish-white scales that often appear on the scalp, eyebrows, eyelids, nasolabial folds, and chest.
• Etiology and Pathogenesis: The exact cause is unknown, but it is believed to be related to:
  • Overgrowth of a yeast-like fungus (Malassezia globosa) on the skin.
  • Abnormal immune response.
• Management: Treatment focuses on controlling the overgrowth of Malassezia and reducing inflammation.
  • First-line treatments: Topical corticosteroids, calcineurin inhibitors (tacrolimus, pimecrolimus), antifungal drugs (ketoconazole, selenium sulfide), and keratolytics (salicylic acid).
  • Second-line treatments: Oral antifungals (fluconazole, itraconazole) are used for systemic involvement or severe cases.
• Prognosis: Seborrheic dermatitis is a chronic condition, but with proper treatment, symptoms can be effectively managed, and remission is possible.

Pityriasis Rosea

• Clinical Features:
  • Presents with an initial "herald patch" which is a larger, oval-shaped lesion often on the trunk.
  • Development of multiple, smaller, oval-shaped lesions (papules) with scales along the lines of Langer (skin tension lines).
  • Lesions often follow a Christmas tree pattern on the trunk.
• Diagnosis: Based on clinical presentation and characteristic features.
• Management: Treatments are focused on symptom relief.
  • Topical corticosteroids (hydrocortisone, clobetasol) can be used for mild cases.
  • Oral antihistamines (cetirizine, loratadine) may be used for itching.
  • Phototherapy may also be used in severe cases.

Pityriasis Rubra Pilaris

• Clinical Characteristics: Chronic inflammatory skin disorder characterized by follicular (hair follicle) papules and scales, often diffusely distributed and associated with intense itching.

• Types of PRP: Different clinical presentations including:

  • Classic Type: Most common type with widespread, follicular, and scaling papules.
  • Generalized Type: More severe form with extensive involvement, including the palms and soles.
  • Palms and Soles Type: Only the palms and soles are affected.

• Etiology and Pathogenesis: The exact cause is unknown, but it is believed to involve:

  • Dysregulation of the immune system, leading to inflammation.
  • Abnormal proliferation of keratinocytes around hair follicles.

• Diagnosis: Diagnosis is based on the characteristic clinical presentation.

• Management: Treatment aims to control inflammation and relieve symptoms.

  • Topical corticosteroids (clobetasol, betamethasone) are used to reduce inflammation.
  • Oral retinoids (acitretin, etretinate) are often effective, but they have potential side effects.
  • Phototherapy (narrowband UVB or PUVA) can be beneficial.

• Prognosis: PRP can be challenging to treat and often causes chronic flare-ups.

Parapsoriasis

• Clinical Features: Characterized by scaly, reddish patches (plaques) that can be small or large.

  • Large plaque parapsoriasis (LPP): Presents with larger, well-defined plaques that frequently involve the trunk and limbs.
  • Small plaque parapsoriasis (SPP): Characterized by numerous, smaller plaques often found on the trunk, legs, and arms.

• Etiology and Pathogenesis: Cause is still unclear.

  • Possible factors include:
    • Abnormal T-cell response.
    • Viral infection.
    • Environmental triggers.

• Management: Treatment focuses on symptom management and reducing inflammation.

  • Topical corticosteroids are often used, but their effectiveness is variable.
  • Phototherapy (UVB or PUVA) may be helpful in some cases.
  • Systemic therapy with cyclosporine or methotrexate is considered for severe cases.

• Prognosis: SPP is typically benign, but LPP can be more aggressive and may progress to a more serious form of skin cancer called mycosis fungoides in rare cases.

Pityriasis Lichenoides

• Clinical Features: Characterized by small, red papules (bumps) with scales.
  • Clinical Presentation: - Usually, a chronic, recurrent condition. - Can be divided into three varieties: - Pityriasis lichenoides et varioliformis acuta (PLEVA):* Acute phase with rapid development of lesions. (See figure 51) ** - Pityriasis lichenoides chronica (PLC): Chronic phase with more slowly developing lesions. - Pityriasis lichenoides with ulceronecrosis and hyperthermia (PLUH): Rare and more severe form with ulcerating lesions and fever.
• Epidemiology: Can affect individuals at various ages, but more commonly in adolescents and young adults.
• Diagnosis: Diagnosis is based on clinical examination. Biopsies are used to rule out other conditions.
• Management: Treatment focuses on reducing inflammation and controlling symptoms.
  • First-line treatment: Topical corticosteroids, phototherapy, and oral antibiotics (erythromycin, tetracycline, minocycline, azithromycin).
  • Second-line treatment: Oral medications (prednisone, methotrexate), cyclosporine, and retinoids are used for more severe cases.
• Prognosis: Pityriasis lichenoides is often a chronic condition, but with proper treatment, most individuals can achieve significant symptom improvement and remission.

Mycosis Fungoides

• A type of cutaneous T-cell lymphoma that is characterized by slow-growing, itchy patches of skin.
• Clinical Presentation:
  • Patch stage: Scaly, reddish patches, often on the trunk, limbs, and face.
  • Plaque stage: Similar to patch stage, but the lesions become thicker and more raised.
  • Tumor stage: Lesions are often nodular and can be ulcerated, with a high risk of spreading beyond the skin.
• Diagnosis: Diagnosis is based on skin biopsies, laboratory tests to evaluate the T-cell subtype, and imaging studies to check for spread to other areas of the body.
• Management: Treatment is dependent on the stage and progression of the disease.
  • Early stages: Topical medications (corticosteroids, imiquimod, bexarotene) and phototherapy.
  • Advanced stages: Systemic therapies (methotrexate, cyclosporine, biologic therapies) and radiation therapy.
• Prognosis: Prognosis is variable depending on the stage and type of treatment. Early diagnosis and treatment significantly improve outcomes.

Review Questions

-  A known  complication of **Generalized Pustular Psoriasis** is **hypocalcemia**.  
  (Hypocalcemia refers to abnormally low levels of calcium in the blood.) 
-  **Inverse psoriasis** is characterized by minimal or absent scaling, and it often presents in major skin folds with impaired sweating in those areas.
- **Plaque-type psoriasis** exhibits pin-point bleeding after forcible removal of the outer scales, referred to as the **Auspitz sign**. The lesions commonly affect the extensor surfaces of the extremities.