6 yr old child H/O fever 5 days back which is now afebrile with normal muscle mass, tone and reflex, no neurological deficit but pain on palpating muscles and CPK levels 2000, diagnosis is

Ans.D. Acute viral myositisThe clinical picture suggests the most probable diagnosis is Viral myositis. The specific history of URI suggests influenza myositis. Infectious myositis has a male predominance and are typically seen in young adults. The typical presentation of the childhood form includes fever, malaise, and rhinorrhea which is usually followed in 1-7 days by severe pain, especially in the calves. The muscle pain is usually worse with movement and the symptoms last for about a week. Muscle weakness, tenderness, and swelling are usually seen with more severity in adults and the Proximal muscles are affected predominantly.In children, toe walking and wide-based gait may be seen because of the involvement of the gastrocnemius-soleus muscles. Lab features of influenza myositis includeElevated CK may be as high as 500 times normalUrine myoglobin is usually positive