Answers to Dermatophile

ANSWER TO QUESTION 1 The answer is (F)—Erythema infectiosum (EI): EI is a rash caused by parvovirus B19, also known as The Fifth Disease. 2 It is common in school-aged children, especially during winter and spring. The pathogenesis is still not fully understood. Infection is transmitted through the respiratory tract and symptoms such as headache, fever and myalgia end after 5 to 7 days with the production of anti-B19 immunoglobulin M (IgM) antibodies. 2 The anti-B19 IgG appears during the third week of illness and coincides with the appearance of the rash and arthralgia. It presents as an asymptomatic infection in approximately 50% of cases. The most characteristic sign is known as ‘slapped cheek’, due to the fiery-red facial erythema occurring within 3 days of the onset of prodromal symptoms. Exposure to sunlight or heat worsens the rash. In the evolution of the condition, the patient develops an itchy and evanescent reticulate rash on the extremities and trunk. In some cases there are transient joint symptoms, mainly involving the metacarpophalangeal and proximal interphalangeal joints, knees, wrists and ankles. The diagnosis is made clinically but laboratory tests can help. Differential diagnoses include phototoxic reaction, systemic lupus erythematosus, rubella, measles, scarlet fever and drug reactions. Because the disease is self-limited in immunocompetent patients, treatment is basically supportive. Parvovirus B19 has an affinity for the erythrocyte precursors, which can result in red series changes (transient aplastic crisis). Therefore, immunocompromised patients and patients with haemolytic anaemia do not always present with the characteristic dermatological findings and are at high risk for the development of severe anaemia.