Contributed by Hui-Yuan Su, MD, Chun-Chieh Wu, MD, Aij-Lie Kwan, MD,PhD, Chih-Lung Lin, MD,PhD, Ann-Shung Lieu, MD,PhD, Yu-Feng Su, MD
FINAL DIAGNOSIS
Atypical Teratoid/Rhabdoid Tumor.
DISCUSSION
Atypical teratoid/rhabdoid tumors (AT/RTs) are rare. Although 95% of these neoplasms occurred in the posterior fossa of children under the age of five years, ATRTs also occur rarely in adults where they largely manifest supratentorially. Since the first adult patient with a malignant CNS RT was reported in 1987, 54 adult cases (greater or equal to 18 years of age) of malignant RT or AT/RT have been documented in the literature thus far [4]. Occurrence of AT/RT in the sellar/suprasellar region is rare, with only nine cases reported so far.
At the first time of operation through the trans-sphenoid approach, most of the specimen we got is normal pituitary glands. Due to rapid growth of the tumor in one month, another operation of pterional approach for subtotal tumor resection is performed. Pre-operation differential diagnosis including pituitary carcinoma or carcinosarcoma, malignant meningioma, germ cell tumors, metastases, and astrocytoma were impressed according to clinical and radiology result. At the microscopic level, the tumor is predominantly composed of rhabdoid cells with prominent nucleoli. Further immunochemistry staining disclosed positive results of EMA, VIM and HHF-35 illustrated reactivity of the rhabdoid cells. Besides, INI-1 loss is noted. According to WHO classification of tumors of the central nervous system, revised 4th edition , the pathologic result is an atypical teratoid / rhabdoid tumor. For the above condition, we presume that the normal pituitary gland might be pushed downward by the above rapid growing tumor, so the specimen we gather through the trans-sphenoid approach is the normal tissue of the pituitary gland.
AT/RT is characterized by an aggressive clinical behavior in most pediatric patients, who usually die within approximately one year after the diagnosis despite aggressive therapy, while adult patients are reportedly better with some longer-term survivors. A recent report suggest that cerebral location of an AT/RT renders the tumor amenable to gross total resection as well as aggressive adjuvant chemoradiation therapy available in adults, which would not be tolerated by small children. In the clinical observation, rapid growing with adjacent extension and distant metastasis after subtotal resection without immediate treatment due to absence of definite diagnosis at the first time of operation is noted [3]. Early reports suggested that because of the young age of the patients and the large extent of the tumor at the time of diagnosis , total or near-total resection could be obtained in less than one third of patients. In the data available in the registry, the overall median survival was 8.5 months; for 13 patients who had a gross total resection, the median event free survival was 14 months; for those with a lesser resection, the median event-free survival was 7 months [2]. The above condition reflects the fact that AT/RT show a greater tendency to disseminate intracranially and metastasize extracranially. Partial resection might make it possible to extend and metastasize [3].
A similar situation as our case is noted in the literature. A case diagnosed of pituitary macroadenoma after a previous endonasal transsphenoidal resection has recurrent headache and left cavernous sinus syndrome. Brain MRI also showed a tumor regrowth in the original location. Further operation of a near complete transsphenoidal resection of the sellar mass was performed followed by 3 months of stereotactic radiotherapy. The further histopathological diagnosis is AT/RT. This combined approach, performed before the final pathological diagnosis, allowed us to observe a better prognosis in the patient with a survival of 30 months [1]. On the contrary, our patient should have better outcome if total resection of the tumor and early intervention of the radiotherapy were performed before the definite diagnosis which was confirmed three months later.
Although the case is rare, AT/RT should be considered in differential diagnosis of an unclear malignant sellar/suprasellar tumor in adults. There is no definite treatment protocol for AT/RT in adults. Optimal treatment including radical removal of the tumor combined with adjuvant radiotherapy and chemotherapy is an acceptable method considering better prognosis compared with AT/RT in young children.
REFERENCES
Contributed by Hui-Yuan Su, MD, Chun-Chieh Wu, MD, Aij-Lie Kwan, MD,PhD, Chih-Lung Lin, MD,PhD, Ann-Shung Lieu, MD,PhD, Yu-Feng Su, MD
International Society of Neuropathology