Paraganglioma of the sellar region
Paragangliomas are rare neuroendocrine tumors that might affect several different regions including head and neck, adrenal, filum terminale and even central nervous system. Paragangliomas affecting the sellar region are extremely rare with a few documented cases so far (1, 2, 3, 4, 5, 6).
The development of paragangliomas in unusual regions such as the sella turcica might be due to the presence of remnants of paraganglionic tissue or due to abnormal migration; it is important to notice that no paraganglionic cells are detected in pituitary or adjacent tissue in adults. However in fetal and neonatal period, neural crest tissue might be seen in avian embryo and these cells could be the origin of abnormal paraganglionic tissue. Furthermore, aggregates of paraganglionic cells were seen in glossopharyngeal nerve within petrous bone in previous reports.
The differential diagnosis of paraganglioma of the sellar region must include pituitary adenomas and meningiomas, both more frequently seen than this unusual lesion. Other clear cell tumors must be also considered in the differential diagnosis, including metastatic renal carcinoma and melanoma. There is no specific clinical or radiological presentation for this rare lesion and histological examination is required for diagnosis. In this case, the characteristic finding of clusters of neuroendocrine tumor cells (zellballen) and the presence of scattered S-100 sustentacular cells are classic for paraganglioma. The negativity for epithelial markers is important to rule out metastatic carcinoma while the negativity for vimentin, HMB45, melan-A and S100 helps to rule out melanoma.
In the present case the clinical and radiological findings suggested a pituitary adenoma, probably with prolactin production inducing amenorrhea and galactorrhea in the clinical evaluation. After surgical treatment the final diagnosis of paraganglioma was confirmed.
Contributed by Alexandre do Nascimento, MD; Luana A. Maranha, MD; Renata A. Corredato, MD; João Cândido Araújo, MD; Luiz F. Bleggi-Torres, MD, PhD