Objective Medically treatable disorders constitute an important part in the evaluation of a child or adolescent presenting with psychotic manifestations.

Methods A four-year-old girl presented to a pediatrician with evident changes in her personality and behaviour over the last two weeks. The changes included muteness, indifference to the outside world, resistance to being touched, avoidance of males, frequent awakenings, loss of appetite, willingness to die, abstraction, difficulty in comprehension, increased dependence on her mother, disruption of amicable relations in day care, loss of eye contact, loss of laughter, obstinacy, and enuresis. She had fevers exceeding 38°C every night. She was referred to a child psychiatrist and then referred to our university clinic for further evaluation.

The family history of the child revealed a past depression in her father, an undescribed psychiatric illness in the grandfather, and attention deficit hyperactivity disorder in her cousin.

The physical examination showed an axillary temperature of 38°C, and hyperemic and hypertrophic tonsils.

Initial laboratory tests were normal except leukocytosis (22,100/µL), an elevated C-reactive protein (3.2 mg/dL), and an elevated erythrocyte sedimentation rate (112 mm/hour). The chest x-ray showed an infilrative area consistent with pneumonia in right lung. Mycoplasma pneumoniae IgM was positive.

Results Azithromycin was started. On day 3 of the therapy, the symptoms and signs abated and disappeared soon afterwards.

Conclusions Among the medical conditions that rarely cause pediatric psychosis symptoms, infectious causes, especially Mycoplasma infection, should be kept in mind.