tailieunhanh - Chapter 056. Cutaneous Drug Reactions (Part 5)

Onychomadesis Onychomadesis is caused by temporary arrest of nail matrix mitotic activity. Common drugs reported to induce onychomadesis include carbamazepine, lithium, retinoids, and chemotherapeutic agents such as cyclophosphamide and vincristine. Paronychia Paronychia and multiple pyogenic granuloma with progressive and painful periungual abscess of fingers and toes are a side effect of systemic retinoids, lamivudine, indinavir, and anti-EGFR monoclonal antibodies (cetuximab, gefitinib). Nail Discoloration Some drugs, including anthracyclines, taxanes, fluorouracil, and zidovudine, may induce nail bed hyperpigmentation through melanocyte stimulation. It appears to be reversible and dose-dependent. . | Chapter 056. Cutaneous Drug Reactions Part 5 Onychomadesis Onychomadesis is caused by temporary arrest of nail matrix mitotic activity. Common drugs reported to induce onychomadesis include carbamazepine lithium retinoids and chemotherapeutic agents such as cyclophosphamide and vincristine. Paronychia Paronychia and multiple pyogenic granuloma with progressive and painful periungual abscess of fingers and toes are a side effect of systemic retinoids lamivudine indinavir and anti-EGFR monoclonal antibodies cetuximab gefitinib . Nail Discoloration Some drugs including anthracyclines taxanes fluorouracil and zidovudine may induce nail bed hyperpigmentation through melanocyte stimulation. It appears to be reversible and dose-dependent. PRURITUS Pruritus is a common symptom of most drug eruptions but it may also occur without skin lesions as the only manifestation of drug intolerance. Severe pruritus may occur in up to 50 of African patients treated with antimalarials and lead to poor compliance. It is much rarer in Caucasians. Immune Cutaneous Reactions Benign MACULOPAPULAR ERUPTIONS Morbilliform or maculopapular eruptions are the most common of all drug-induced reactions often start on the trunk or areas of pressure or trauma and consist of erythematous macules and papules that are frequently symmetric and may become confluent. Involvement of mucous membranes is unusual with the exception of scaly lips the eruption may be associated with moderate to severe pruritus and fever. Diagnosis is rarely assisted by laboratory testing. Skin biopsy is useless because it shows normal skin or very mild and nonspecific changes. A viral exanthem is the principal differential diagnostic consideration especially in children. Absence of enanthems absence of symptoms in ears nose and throat and upper respiratory tract and polymorphism of the skin lesions support a drug rather than a viral eruption. Maculopapular reactions usually develop within 1 week of initiation of therapy and last