Intraosseous calvarial haematoma mimicking a skull tumour in a child with Noonan syndrome: a case report.

Noonan syndrome is a multisystem genetic disorder associated with skeletal abnormalities and an increased risk of certain neoplasms. However, intraosseous calvarial haematoma has not been previously reported in this population. We present a 14-year-old female with Noonan syndrome who developed progressively enlarging calvarial lesions associated with headache, visual disturbance, and tinnitus. Imaging demonstrated expansile osteolytic lesions with mass effect, raising suspicion for neoplasia. The patient underwent surgical excision, which was complicated by significant intraoperative haemorrhage requiring transfusion. Histopathological analysis confirmed an intraosseous haematoma without evidence of malignancy. This case highlights the importance of considering non-neoplastic causes in calvarial lesions in patients with Noonan syndrome and underscores the potential for significant bleeding despite unremarkable coagulation profiles.