Characteristics of Bone Destruction in Cranial Vault Lymphoma Compared with Other Skull Tumors.

Cranial vault lymphomas are rare and challenging to diagnose. We present herein two cases of cranial vault lymphoma. The first patient was a 72-year-old woman who presented with a large mass in the parietal bone found incidentally following a head injury. The second patient was a 63-year-old man who presented with an occipital subcutaneous mass associated with visual disturbance and occipital headaches. The diagnosis of a malignant tumor in the second patient was straightforward due to his symptoms and considerable bone destruction, but the first patient was more difficult to diagnose due to a lack of symptoms and only slight bone destruction detected by computed tomography (CT). Both were histophathologically diagnosed with diffuse large B cell lymphoma (DLBCL) in the cranial vault. We also investigated the clinical features, including initial symptoms and patterns of bone destruction, in 23 patients with other types of skull tumors. This comparison showed that cranial vault lymphomas cause large masses on the scalp and lead to characteristic incomplete bone destruction, indicating that cranial bone is destroyed very slowly despite the expanding subcutaneous mass. This feature is unique compared with other benign and malignant skull tumors. In addition, cranial vault lymphoma can be confirmed via bone window CT.