Computed tomography and magnetic resonance imaging features of solitary langerhans cell histiocytosis in calvaria

Purpose: To assess the computed tomography (CT) and magnetic resonance imaging (MRI) features of Langerhans cell histiocytosis (LCH) in calvaria. Methods: The CT and MRI manifestations of 12 pathologically proven cases of solitary LCH involving the cranial bone were retrospectively analyzed. Assessed image features included: Location, size (soft-tissue mass and bone destruction), shape (soft-tissue mass and bone destruction), margins, attenuation and changes in adjacent bone on CT, and signal intensity and enhancement pattern on MRI. Results: The lesions were solitary, lytic, punched out, round to oval or geographic (size larger than 3 cm); With the appearance of bone destruction with a gourd-shape (n=12); And a soft-tissue mass extending from the subcutaneous to the intracranial space. On CT, a beveled edge was seen in all cases and button sequestration in two cases, but sclerotic rim was not evident. The hypoattenuated soft-tissue mass was mostly with patches of slight hypoattenuation spot (6/9 cases). On MRI, all cases showed long or iso-T1 and heterogeneous high T2 signal intensity relative to the brain. Diffusion-weighted images displayed mild hyperintensity (5/7 cases) or a low hypointensity (n=2). Postcontrast MR images demonstrated heterogeneous marked enhancement (n=7). A tail of dural and galea enhancement was seen in all cases. The adjacent bone marrow (4/10 cases) exhibited low intensity on T1-weighted images without gadolinium enhancement. Conclusion: Although the diagnosis of a calvarial LCH mainly depends on pathology, the imaging findings have value as well. CT and MRI have their own advantages in the diagnosis of LCH. Combined application of CT and MR examinations is recommended for patients with suspected LCH.