Pituicytoma Coexisting With Corticotroph Hyperplasia

Abstract

Pituicytoma is a rare, low-grade glial neoplasm that arises in the neurohypophysis or infundibulum and usually presents as pituitary gland enlargement. They are often misdiagnosed as pituitary adenomas. Causes have varied for high serum adrenocorticotropic hormone level reported in a few patients with pituicytoma.We report a rare case of pituicytoma accompanied by corticotroph hyperplasia—a challenging diagnosis guided by clinical presentations, radiological signs, and biopsy.We present a case of pituicytoma with corticotroph hyperplasia in a 46-year-old woman with typical Cushing syndrome. Magnetic resonance imaging revealed a lesion in the sellar area with equal T1 and T2 signals and marked homogeneous enhancement. We present detailed analysis of the patient's disease course and review pertinent literature. Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor of this journal. Because of this, there is no need to conduct special ethic review and the ethical approval is not necessary.The patient underwent a surgical exploration and tumor resection through a trans-sphenoidal approach. Pathologic results revealed pituicytoma and corticotroph hyperplasia. As adrenocorticotropic hormone and cortisol levels did not decrease to normal, the patient received radiotherapy and recovered uneventfully. No recurrence was found over 8 years of follow-up.Pituicytoma is a rare type of sellar tumor. Pituicytomas in patients with Cushing syndrome are rarer still. To our knowledge, this is the first report of Cushing syndrome caused by corticotroph hyperplasia in a pituicytoma patient.

A 53‐year‐old woman with Cushing's disease and a pituitary tumor

“…However, no pituitary adenoma was evidenced at histological examination of the surgical fragments. Elevated serum levels of ACTH were previously evidenced in four patients (two male and two female: three adults and one child) with pituicytoma . In one of those cases, pituicytoma co‐existed with histologically proven corticotroph hyperplasia of adenohypophysis and in another case it was associated with histologically confirmed ACTH‐secreting pituitary adenoma .…”

“…Elevated serum levels of ACTH were previously evidenced in four patients (two male and two female: three adults and one child) with pituicytoma. 1,[10][11][12] In one of those cases, pituicytoma co-existed with histologically proven corticotroph hyperplasia of adenohypophysis 1 and in another case it was associated with histologically confirmed ACTH-secreting pituitary adenoma. 12 Nonetheless, in the remaining two patients, neither ACTH-secreting pituitary adenoma, nor corticotroph hyperplasia were found at the microscopic evaluation of surgical specimens, 10,11 similar to that shown in the present case.…”

“…Pituicytoma is supposed to derive from the neoplastic transformation of pituicytes, which are specialized glial cells of neurohypophysis . It is histologically composed of elongated bipolar spindle cells arranged in fascicles or in a storiform pattern and it has peculiar a immunohistochemical profile, with positive staining for vimentin, S100 and TTF‐1, variable (patchy to diffuse) staining for GFAP and EMA and absence of staining for cytokeratins, synaptophysin, chromogranin and pituitary hormones …”

“…6 It is histologically composed of elongated bipolar spindle cells arranged in fascicles or in a storiform pattern 5 and it has peculiar a immunohistochemical profile, with positive staining for vimentin, S100 and TTF-1, variable (patchy to diffuse) staining for GFAP and EMA and absence of staining for cytokeratins, synaptophysin, chromogranin and pituitary hormones. 1,5,7 Due to its morphology, it enters the differential diagnosis with other spindle-shaped tumors, including pilocytic astrocytoma, fibrous meningioma and schwannoma. Absence of biphasic pattern as well as of Rosenthal fibers and eosinophilic granular bodies in pituicytoma are helpful diagnostic features to differentiate this entity from pilocytic astrocytoma.…”

Correlations between clinical hormone change and pathological features of pituicytoma

“…After a review of the English literature, only two case reports of pituicytoma with hormone elevation were found; in both, the patients presented with Cushing disease. 7,8 These reports also provided some indications of hormone elevation, but lacked sufficient pathological and immunohistochemical (IHC) examination to confirm this phenomenon. It is unclear whether pituicytoma influences endocrine secretory functions or whether it can raise a normal pituitary gland to hypersecretory status; there has also been no analysis of coexisting pituicytoma and functioning pituitary adenoma tumours.…”