It has occasionally been reported that mechanical
trauma and posttraumatic
inflammation may promote
metastasis from a primary
tumor to the site of the
trauma. However, the etiologies that contribute to the
metastasis formation at the
trauma site remain unknown. We describe here the first case of skull
metastasis from
hepatocellular carcinoma (HCC) revealing a growing subcutaneous mass at the site of
skull fracture. A 58-year-old man had undergone surgical resection of a primary
tumor in the liver 2 years previously and was in clinical remission. The patient fell head first off his bicycle and suffered a
skull fracture in the squamous portion of the left temporal bone without ostelysis. Three months after the
head trauma, he presented at our department with a growing lump on the left side of his head, and magnetic resonance (MR) imaging revealed an osteolytic
tumor extending into the adjacent subcutaneous and epidural space. The
tumor was at the same location as the
skull fracture sustained in the bicycle accident. The mass lesion was radically resected with surrounding normal bone. The
tumor formed a well-demarcated mass with
osteolysis of the inner and outer skull tables, and the inner layer of the dura mater was intact. The histological diagnosis for the surgical specimen from the skull
tumor was a HCC identical to the primary
tumor. Immunohistochemically, the
tumor cells were diffusely and strongly positive for
vascular endothelial growth factor (
VEGF) and basic fibrous
growth factor (bFGF). It is well known that the extracellular matrix and
cytokines are involved in the processes of not only bone healing but also
metastasis formation. The present case suggests that several processes involved in bone healing modified the microenvironment and represent a possible cause of skull
metastasis from primary
tumor.