MRCP UK EXAMINATIONS

A child complains of the general weakness, a pharyngalgia at swallowing and nausea. Objectively, a bright reddening revealed in fauces; tonsils were enlarged. Later, the fine, densely located maculae, size about papaverous grain, appeared on a neck, in the top of a back and a breast. Microscopical investigation showed in a mucosa and tonsils tissue an acute plethora and grayish, dim areas of necroses. On the periphery of the necrotic zones, within the edema and fibrinous inflammation areas, the chains of streptococcuses were defined. What is the most likely diagnosis?