Chapter 16: Dermatitis

Atopic dermatitis is a chronic inherited disorder characterized by impaired epidermal barrier function due to filaggrin protein deficiency and dysregulated immune responses with elevated immunoglobulin E levels. The condition presents as severe pruritus preceding visible rash, with lichenified, scaly lesions in flexural areas during adulthood. Management centers on intensive skin hydration through emollients and occlusive bathing techniques, supplemented by topical corticosteroids during acute exacerbations and calcineurin inhibitors for maintenance therapy. Contact dermatitis comprises irritant-induced cytotoxic reactions and allergic delayed-type hypersensitivity responses to specific antigens such as plant resins, metals, and chemical compounds. Clinical presentation features pruritic vesicular eruptions with characteristic distributions determined by the offending agent, and management prioritizes identification and elimination of the causative substance alongside supportive care with compresses and topical corticosteroids. Seborrheic dermatitis is an inflammatory condition associated with Malassezia furfur yeast colonization in sebaceous gland-rich regions and commonly presents as pink, greasy-scaled patches on the scalp and face, responding well to antimycotic shampoos and topical antifungal agents. Psoriasis represents an immune-mediated hyperproliferative disorder involving clonal T-cell activation that dramatically accelerates epidermal turnover from the normal twenty-eight-day cycle to three to four days, resulting in characteristic silvery-scaled plaques on extensor surfaces and the scalp. Psoriatic pathophysiology is triggered by trauma, streptococcal infection, stress, and certain medications, with clinical manifestations including Auspitz's sign and Köbner phenomenon. Disease management ranges from topical agents including corticosteroids and vitamin D derivatives for mild involvement to phototherapeutic approaches and systemic immunosuppressive or biologic therapies targeting tumor necrosis factor alpha and interleukin pathways for severe cases. The chapter also addresses significant comorbidities associated with psoriasis, including arthritis, cardiovascular disease, and depression.