Review of imaging modalities and radiological findings of calvarial lesions.

Calvarial lesions are usually incidental and asymptomatic, rarely detected. However, these lesions can also present with pain, a palpable mass or a bone defect. Clinical information such as the patient's age and medical history are helpful in making the correct diagnosis. Calvarial lesions may occur due to congenital and anatomical variants, traumatic and iatrogenic, idiopathic, infectious and inflammatory, metabolic, benign and malignant neoplastic causes. Calvarial lesions may be solitary, multiple or diffuse, and may be lytic, sclerotic or mixed. Although most calvarial lesions are benign, radiologic imaging features can help to determine whether the lesion is benign or malignant. Methods that can guide treatment and are currently in use include plain radiography, ultrasonography, computed tomography, magnetic resonance imaging, angiographic studies, and nuclear scintigraphy studies such as 18F-fluorodeoxyglucose positron emission tomography and whole-body bone scintigraphy. Defects, lysis and sclerosis in the bone structure are assessed by plain radiography and computed tomography, and the soft tissue components of the lesions and their relationship to the surrounding soft tissue are assessed by magnetic resonance imaging. This article reviews the imaging findings of benign and malignant calvarial lesions and normal variants that may be confused with systemic diseases and pathologies affecting the calvarium.