An unusual case of atypical lymphocytosis.

Atypical lymphocytosis due to infections is classically seen in viral and chronic bacterial infections. A four year old boy with acute streptococcal infection presented at Al-Nahdha Hospital, Muscat, Oman, with follicular tonsillitis and bilateral cervical lymphadenitis. The blood film showed 33% atypical lymphocytes. Serologically, immunoglobulin M (IgM) antibodies were positive for cytomegalovirus, herpes simplex virus, and Epstein Barr virus, but the patient responded dramatically to antibiotics.