The age of onset is usually between 15 and 50 years. Blacks, whites, and Asians are equally affected. The dominant nature of the inheritance of von Hippel-Lindau disease is well known. Seizinger and coworkers, in cases associated with renal cell carcinoma and pheochromocytoma, localized a defect in a tumor suppressor gene (termed VHL; see Chap. 37).
The diagnosis can be deduced from the appearance on CT or MRI of a cerebellar cyst containing an enhancing nodular lesion on its wall. Often, the associated retinal hemangioma will be disclosed by the same imaging procedure. The angiographic picture is also characteristic: a cluster of small vessels forming a mass 1.0 to 2.0 cm in diameter (Fig. 30-14). Craniotomy with opening of the cerebellar cyst and excision of the mural hemangioblastomatous nodule is usually curative, but there is a high rate of recurrence if the entire tumor, including the nodule, is not completely removed. In the series of Boughey and colleagues, the lesion was successfully excised in 80 percent of patients; 15 percent of patients, who had only partial resection of an isolated cerebellar lesion, developed recurrent tumors. More recently, several groups have used endovascular embolization of the vascular nodule prior to surgery, but it is not clear if this reduces the incidence of recurrence. Treatment with focused radiation is also being undertaken, particularly for multifocal or surgically inaccessible lesions, and several case series using either stereotactic radiosurgery, or external or proton beam radiation indicate results that may be comparable to conventional treatment.
Hemangioblastomas of the spinal cord are frequently associated with a syringomyelic lesion (greater than 70 percent of cases); such lesions may be multiple and are located mainly in the posterior columns. A retinal hemangioblastoma may be the initial finding and leads to blindness if not treated. New retinal lesions continue to be formed over a period of years while the patient is under observation. The children of a parent with a hemangioblastoma of the cerebellum should be examined regularly for an ocular lesion and renal cell carcinoma and genetic testing is appropriate in some instances.
There has been uncertainty as to the proper classification of pineal tumors. Originally they were all thought to be composed of pineal cells; hence they were classified as true pinealomas, a term suggested by Krabbe. Globus and
Silbert believed that these originated from embryonic pineal cells but Russell later pointed out that some tumors in the pineal region are really atypical teratomas resembling the seminoma of the testicle. Four types of pineal tumors are now recognized: germinoma, nongerminatous germ cell tumors, pinealoma (pineocytoma, atypical pineocytoma, and pineoblastoma), and a glioma originating in astroglial cells of the pineal body. Some would include teratomas in this group. Currently, they are assigned a category of their own with 4 subtypes ranging from grade I (pineocytoma) to IV (pineoblastoma).
Of the four groups of pineal tumors, approximately 50 percent are germinomas. The pinealomas, pineoblastomas, and gliomas are less frequent. Children, adolescents, and young adults—males more than females—are affected. Only rarely does one see a patient with a pineal tumor that has developed after the 30th year of life.