Pseudotumor of the scalp caused by a chronic hygroma with a traumatic CSF fistula.

A 6 1/2-year-old child, who had suffered a depressed fracture of the skull at the age of 1 1/2, had an extensive tumor of the scalp. Microscopic evaluation showed the growth to be a pseudotumor. The spongy tissue proved to be a chronic subdural hygroma containing structures resembling pacchionian granulations. A CSF fistula was demonstrated surgically. The fistula was assumed to be responsible for the metaplastic proliferation of subcutaneous and galeal connective tissue. A growing fracture was not present.