Brain Pathology Case of the Month - September 1998

FINAL DIAGNOSIS:    Pilocytic astrocytoma with cystic degeneration and evidence of old and fresh hemorrhage.

DISCUSSION:

Gliomas of the anterior optic pathways account for 7% of central nervous system tumors in children and 2% in adults (1). Pilocytic astrocytoma is the most common glioma of the optic pathway and 98% of them occur in individuals aged 25 years or younger (2).

Morphologically, pilocytic astrocytomas of the optic pathway resemble their cerebellar counterparts but they differ in that cyst formation is extremely rare in the former but frequent in the latter. Further, though cystic change has been reported in optic chiasmal and pathway tract tumors (3-6). To the best of our knowledge, there are only two reports in the English-language literature of cystic change in optic nerve tumors (7,8). In an earlier study from our Institute of 35 cases of optic nerve glioma, no cystic change was noted in any of them (9).

The case described by Rand et al (7) was a 4.5 year old male who presented with unilateral exophthalmos and the tumor involved both optic chiasma and optic nerve. Charles et al (8) reported another case in a 26 year old female who presented with sudden visual loss but there was no proptosis. In both these cases however, the cystic component was very small. In contrast the present case had a large cyst measuring 9x8x5 cms, after aspiration of 300 ml dark fluid.

Cystic change in pilocytic astrocytomas may be because of secretion of mucopolysaccharides into the microcyst. It may also be the result of sudden hemorrhage into the tumor (8) and this was possibly the cause of cystic change in the present case also. Rarely, cystic change may be result of necrosis but this is usually seen in high grade gliomas.

ACKNOWLEDGEMENT:

The authors wish to thank Mr. Rajeshwar Khadia for immunostaining and Mr. Kamal for secretarial assistance.

REFERENCES:

1. Housepian EM, Marquardt MD, Behren M. Optic glioma (1985). In : Wilkins RH, Rengachary SS eds. Neurosurgery. New York : McGraw Hill 916-21.
2. Yonoff M, Davis RL, Zimmerman LE (1978). Juvenile pilocytic astrocytoma ("glioma") of optic nerve. Clinicopathologic study of 63 cases. In : Jakobiec FA ed. Ocular and adrenexal tumors. Birmingham. Aesculapius Publishing Co. pp 655-707.
3. Gower DJ, Pollay M, Shuman RM, Brumback RA (1990). Cystic optic glioma. Neurosurg 26 : 133-7.Wilson WB, Finkel RS, McCleary L, Dreisbach JN, Rak K (1990). Large cystic optic glioma. Neurology 40:1898-1900.
4. Hiyama H, Kubo O, Nakajima H, Hayashi M, Kagawa M (1992). A case of cystic optic glioma involving chiasma and bilateral posterior optic pathway. No Shinkey Geka 20:1199-1204.
5. Tekkok IH, Tahta K, Saglam S (1994). Optic nerve glioma presenting as a huge intrasellar mass. Case report. J Neurosurg Sci 38:137-40.
6. Rand CW, Irvine R, Reeves DL (1939). Primary glioma of the optic nerve.Arch Opthalmol 21:799-816.
7. Charles NC, Nelson L, Brookner AR, Lieberman N, Breinin GM (1981). Pilocytic astrocytoma of the optic nerve with hemorrhage and extreme cystic degeneration. Am J Ophthalmol 92:691-95.
8. Sinha A, Mahapatra AK (1996). tumours of the visual pathway. A study of 35 cases. Indian Pediatr 33:506-509.

Contributed by Mehar C. Sharma MD, Minal Kanse MD, Ashok K. Mahapatra MCh., Shailesh Gaikwad MD, and Chitra Sarkar MD

International Society of Neuropathology