Initial head CT demonstrates a permeative lesion in the left frontal bone with a small soft tissue mass, extraaxial and extracranial but normal underlying brain.
Imaging shown later shows a primary tumor of the right iliac bone due to a primary Ewing’s sarcoma.
Skull lesions in children are rather uncommon.
This patient had known Ewing’s sarcoma, and therefore the etiology of the lesion was likely metastatic.
Other primary lesions which can produce bony metastases in children include neuroblastoma, osteosarcoma, leukemia, thyroid and soft tissue sarcomas.
Primary bone tumors of the skull are also very uncommon.
The most lesions include epidermoid/dermoid(in the midline), Langerhan’s cell histiocytosis (beveled edge), hemangioma(widened diploic space with starburst pattern) or erosion from a slowly growing brain tumor such as an oligodendroglioma.
Other skull lesions which may be in the differential include fibrous dysplasia, cepahlohematoma, normal variants such as enlarged parietal foramina, brown tumor of hyperparathyroidism, osteomyelitis or leptomeningeal cyst.
Most of these lesions have characteristics such as a purely cystic or purely sclerotic appearance that would exclude them from consideration in this case.
TAKE HOME MESSAGE:
Mets to bone in children:
Osteosarcoma
Ewing sarcoma
Rhabdomyosarcoma
Neuroblastoma
Lymphoma, Leukemia
Renal cell carcinoma
Rhabdoid tumor, clear cell and anaplastic tumor of the kidney
PNET
Retinoblastoma
Medulloblastoma
Melanoma
Langerhan cell histiocytosis