Think of … CHICKENPOX

Abstract

1) Pemphigus vulgaris • A chronic autoimmune blistering disease that can affect the skin, mucous membranes, and adnexa. It predominantly occurs between the fourth and sixth decades of life and affects both sexes equally. • There is a strong association between genetic predisposing factors (HLA class II) and inducing factors (stress, drugs, viral infections) that trigger the individual's immune response, leading to the production of autoantibodies against desmogleins 1 and 3. • Mucosal manifestations—primarily in the oral mucosa—are the initial presentation in 50–70% of patients and precede cutaneous manifestations by months. The latter present as flaccid, straw-colored blisters arising on healthy skin that rapidly transform into painful erosions; the Nikolsky sign is positive. • Tzanck test showing acantholytic cells or Tzanck cells (large, rounded, free-floating epithelial cells with ragged edges, homogeneous eosinophilic cytoplasm, and large hyperchromatic nuclei) + histopathology (suprabasal separation containing loose epithelial cells; the basal layer of the epidermis remains attached to the basement membrane, forming the floor of the blister and creating a "row of tombstones" appearance) + direct immunofluorescence (DIF: honeycomb-like deposition of IgG and C3). • High-dose steroids form the basis of treatment, but rituximab (anti-CD20) is used as a first-line medication in moderate to severe cases.

2) Linear IgA dermatosis • A rare autoimmune disease, predominantly affecting children between 6 months and 6 years of age and adults aged 40 to 60. It is characterized by subepidermal blisters with linear IgA deposits along the basement membrane. • The etiology is unknown. It is often preceded by nonspecific viral illnesses or urinary tract infections, or associated with the use of drugs such as vancomycin, beta-lactams, cephalosporins, NSAIDs, or ACE inhibitors (e.g., captopril). • Acute onset of urticarial plaques featuring tense vesicles or blisters on normal or erythematous skin; these arrange in an annular pattern with central crusting, creating a "string of pearls" appearance. They expand peripherally in a rosette-like pattern. Oral and ocular mucosal involvement is common. • Subepidermal blister containing abundant neutrophils and occasional basophils. Dermis shows a neutrophilic infiltrate. Direct immunofluorescence (DIF) reveals linear, homogeneous IgA deposits along the basement membrane. • Dapsone is the first-line treatment, although corticosteroids may be used during the initial phase. Immunosuppressants may be included in severe cases.

3) Chickenpox (Varicella) • Infection caused by the varicella-zoster virus, a member of the herpesvirus family. It primarily affects children under 10–12 years of age, with peak incidence occurring between the ages of one and 6–8 years. Life-threatening complications may arise in adults and immunocompromised patients of any age. Incidence varies by country depending on regional climate and population vaccination coverage. • Enters via the upper respiratory tract (oropharynx). • Progresses rapidly—within 12 hours—to papules, vesicles, pustules, and crusts. • Begins on the face and scalp and spreads rapidly to the trunk, with less involvement of the limbs. It presents in crops (successive waves of eruptions). • Intraepidermal vesicles, acantholysis, reticular degeneration in the underlying dermis, edema and vasculitis, and multinucleated giant cells with characteristic nuclear changes. • Topical treatment: cold compresses or calamine lotion applied locally, lukewarm baths with colloidal oatmeal, and oral antihistamines. Antivirals: acyclovir, valacyclovir, famciclovir.