A patient aged 5 years and 7 months, with no personal or family history of interest, was admitted to our hospital on 12 June 2002 for a 10-day history of headache, predominantly in the evening, followed by convergent strabismus of the left eye and diplopia. Neurological examination revealed an awake, cooperative and environmentally connected child, with convergent strabismus of the left eye with preserved ocular motility and horizontal nystagmus on forced gaze to the right.
Blood tests, biochemistry and chest X-ray were normal. Cranial CT and MRI showed a well-defined mass located inside the right lateral ventricle at the level of the atrium and temporal horn, of homogeneous density and measuring 6 by 2.5 cm, with significant perilesional oedema and showing intense uptake after administration of intravenous contrast.

The patient underwent a transtemporal approach through the medial temporal gyrus with macroscopically complete excision of the tumour.
The histopathological study showed a neoplastic meningothelial proliferation with a predominantly meningotheliomatous pattern and high cellularity, classifying the tumour as an atypical meningioma. The presence of high mitotic activity was striking, in some areas reaching 2-3 mitoses in 10 high-magnification fields, with the proliferating cells having larger nuclei and prominent nucleoli. The Ki-67 antibody activity, measured randomly in the whole tumour, ranged from 18-20%.

The girl's clinical evolution was favourable and she was discharged from hospital ten days after surgery with minimal convergent strabismus of the right eye. Despite not having undergone complementary treatment, the patient is currently asymptomatic and no signs of recurrence have been detected in follow-up imaging studies.