Granular cell tumor of the neurohypophysis: report of a case with intraoperative cytologic diagnosis

Treatment modalities and outcomes of granular cell tumors and spindle cell oncocytomas of the pituitary gland: an analysis of two national cancer databases

BACKGROUND

Spindle cell oncocytomas (SCO) and granular cell tumors (GCT) are rare primary pituitary neoplasms; the optimal treatment paradigms for these lesions are unknown and largely unexplored. Thus, using national registries, we analyze the epidemiology, management patterns, and surgical outcomes of SCOs and GCTs.

METHODS

The National Cancer Database (NCDB; years 2003-2017) and the Surveillance, Epidemiology, and End Results Program (SEER; years 2004-2018) were queried for patients with pituitary SCOs or GCTs. Incidence, extent of surgical resection, and rate of postoperative radiation use for subtotally resected lesions comprised the primary outcomes of interest. All-cause mortality was also analyzed via time-to-event Kaplan-Meier curves.

RESULTS

SCOs and GCTs have an annual incidence of 0.017 and 0.023 per 1,000,000, respectively. They comprise 0.1% of the benign pituitary tumors registered in NCDB. A total of 112,241 benign pituitary tumors were identified in NCDB during the study period, of which 83 (0.07%) were SCOs and 59 (0.05%) were GCTs. Median age at diagnosis was 55 years, 44% were females, and median maximal tumor diameter at presentation was 2.1 cm. Gross total resection was achieved in 54% patients. Ten patients (7%) had postoperative radiation. Comparing patients with GCTs versus SCOs, the former were more likely to be younger at diagnosis (48.0 vs. 59.0, respectively; p < 0.01) and female (59% vs. 34%, p = 0.01). GCTs and SCOs did not differ in terms of size at diagnoses (median maximal diameter: 1.9 cm vs. 2.2 cm, respectively; p = 0.59) or gross total resection rates (62% vs. 49%, p = 0.32). After matching SCOs and GCTs with pituitary adenomas on age, sex, and tumor size, the former were less likely to undergo gross total resection (53% vs. 72%; p = 0.03). Patients with SCOs and GCTs had a shorter overall survival when compared to patients with pituitary adenomas (p < 0.01) and a higher rate of thirty-day mortality (3.1% vs 0.0%; p = 0.013).

CONCLUSION

SCOs and GCTs are rare pituitary tumors, and their management entails particular challenges. Gross total resection is often not possible, and adjuvant radiation might be employed following subtotal resection.

Granular Cell Tumor and Spindle Cell Oncocytoma of the Pituitary Gland: Imaging and Intraoperative Cytology Diagnostic Dilemmas and Management Challenges

BACKGROUND

 Tumors arising from the posterior pituitary gland are rare and closely resemble pituitary adenoma in presentation and imaging. Most of them come as a histopathologic surprise. We have analyzed the posterior pituitary tumors managed in our institute and have discussed the dilemmas in imaging, challenges in intraoperative squash cytology, and surgical management.

METHODS

 We retrospectively reviewed our operative database of pituitary tumors over the past 10 years, which included five posterior pituitary tumors (three granular cell tumors [GCTs] and two spindle cell oncocytomas [SCOs]). Clinical, imaging, and endocrine characteristics; intraoperative details; histopathologic features; and postoperative outcomes were collected and analyzed.

RESULTS

 The mean age of the patients was 47 years. All patients presented with varying degrees of vision loss. Radiology revealed a sellar / suprasellar lesion with the pituitary gland seen separately in two of three GCTs, whereas a separate pituitary gland could not be identified in both the SCOs. Pituitary adenoma was a radiologic diagnosis in only two of five cases. Three patients underwent a transsphenoidal surgery, whereas two underwent surgery by the transcranial approach. Intraoperative cytology was challenging, though a possibility of posterior pituitary tumor was considered in three of four cases, whereas one was considered meningioma. All the tumors were very vascular and influenced the extent of resection.

CONCLUSIONS

 GCTs and SCOs are relatively uncommon tumors that are difficult to diagnose on preoperative imaging. Intraoperative squash cytology too can pose challenges. A preoperative suspicion can prepare the surgeon for surgery of these hypervascular tumors. The transcranial approach may be necessary in cases of uncertainty in imaging.

Intraoperative cytology of pituicytomas

BACKGROUND

Pituicytoma is a rare tumor of the sella and suprasellar region. It is common for these tumors to be misdiagnosed radiographically as pituitary adenomas, meningiomas, and craniopharyngiomas. Histologically, pituicytomas are also known to show variable morphology. These factors often complicate intraoperative consultation, especially when tissue is limited.

METHODS

A database search (January 1990-June 2019) identified 13 surgically resected pituicytomas that were sent for intraoperative consultation. The intraoperative cytology was reviewed by two pathologists, and both squash preparations/smears and touch preparations were included.

RESULTS

The cytological features of pituicytomas were variable. The cytoplasm ranged from fibrillary to fine and wispy. The nuclei were round to ovoid with occasional tumors showing spindled morphology. Small nucleoli were seen in all tumors, and chromatin was fine to vesicular. While squash preparations were cellular and revealed cohesive groups of tumor cells, touch preparations were often paucicellular with the exception of one tumor. The cytological features of pituicytomas are compared to those of other tumors with similar radiographic appearances.

CONCLUSIONS

Our findings illustrate the range of cytological features of these rare tumors and highlight the difficulty in making a definitive intraoperative diagnosis. Pituicytomas should be considered in the differential of a sellar/suprasellar lesion with glial and meningioma-like cytological features.

Hypothalamic Endocrine Tumors: An Update

The hypothalamus is the site of synthesis and secretion of a number of endocrine peptides that are involved in the regulation of hormonal activity of the pituitary and other endocrine targets. Tumors of the hypothalamus have been recognized to have both structural and functional effects including hormone hypersecretion. The classification of these tumors has advanced over the last few years, and biomarkers are now available to classify these tumors and provide accurate structure-function correlations. This review provides an overview of tumors in this region that is critical to metabolic homeostasis with a focus on advances in the diagnosis of gangliocytomas, neurocytomas, and pituicytomas that are unique to this region.

Primary tumors of the posterior pituitary: A systematic review

In 2017, the World Health Organization established that pituicytoma, granular cell tumor (GCT), spindle cell oncocytoma (SCO) and sellar ependymomas (SE) are posterior pituitary tumors (PPT). They probably arise from the pituicytes and may constitute a unique histopathological entity. We carried out a systematic review using PubMed's database. A total of 266 patients with pathological diagnosis of PPT (135 pituicytomas, 69 GCT, 47 SCO, 8 SE and 7 mixed histology tumors) were analyzed. Gender distribution was identical and median age at diagnosis was 48 ± 21.8 years. Main presentation symptoms were visual disorders (n = 142; 58.1%), headache (n = 99; 40.5%), hypopituitarism (n = 84; 34.4%), hypercortisolism (n = 10; 4.1%), polyuriapolydipsia (n = 6; 2.4%) and acromegaly features (n = 5; 2.0%). On MRI, 122 (47.6%) patients showed sellar with suprasellar extension masses, 67 (23.1%) were suprasellar and 63 (24.6%) exclusively sellar. Median tumor size was 22.0 ± 14.2 mm. Two hundred sixty four patients underwent surgery, transphenoidal access was selected in 132 (64.4%) and craniotomy in 58 (28.3%). Complications were hypopituitarism (n = 70; 42.1%), diabetes insipidus (n = 55; 33.1%) and hemorrhage (n = 50; 30.1%). Tumor persisted in 93 patients (45.6%) and recurred in 13 (6.4%). Regarding comparison between main types of PPT, SCO patients were diagnosed later (60.0 vs 47.0 vs 47.0 years, p = 0.023), the tumor was larger 25.0 mm [10.8] vs 20.0 mm [14.2] vs 2.0 mm [15.0] and they were frequently sellar with suprasellar extension tumors (71.7% vs 46.2% vs 32.8%, p = 0.003) compared to pituicytoma and GCT. In conclusion, PPT are rare tumors and have been misdiagnosed mainly as non-functioning pituitary adenomas. Different types of PPT share similar epidemiology, clinical manifestations and surgical outcomes. Surgery is the only curative option but complications and subtotal resection are common.

Granular Cell Pituitary Tumor in a Patient with Multiple Endocrine Neoplasia-1

Multiple endocrine neoplasia type 1 (MEN-1) is an autosomal dominant disorder characterized by parathyroid, pancreatic islet, and pituitary tumors. Approximately 40% of MEN-1 patients harbor a pituitary adenoma. Separately, granular cell tumors (GCTs) of the sellar/parasellar region are an exceedingly rare clinical entity with less than 100 reported cases in the literature. These slow-growing, often asymptomatic lesions are difficult to diagnose and may mimic pituitary adenoma, Rathke cleft cyst, or other sellar/supra-sellar pathology. There is no known association with MEN-1 or any other familial syndrome. A 36-year-old neurologically normal woman with known MEN-1 underwent a screening magnetic resonance imaging (MRI) scan which revealed a 10 mm x 6 mm x 7 mm sellar/suprasellar lesion. She underwent endoscopic endonasal transsphenoidal resection. Subsequent neuropathological analysis was consistent with GCT of the pituitary gland. Here we describe the first report to our knowledge of a GCT of the pituitary gland occurring in a patient with MEN-1.

Sellar and suprasellar granular cell tumor of the neurohypophysis: A rare case report and review of the literature

Granular cell tumors of the neurohypophysis are rare tumors with a WHO grade of I. Symptomatic tumors are even more rare. In this case, we present a 50-year-old patient with a sellar and suprasellar granular cell tumor of the neurohypophysis, who reported headaches, blurred vision and unsteady gait. CT imaging showed a sellar and suprasellar mass approximately 2.9 cm in diameter with clear boundaries. Histologically, the tumor lacked any obvious atypia and contained densely arranged polygonal tumor cells with abundant granular eosinophilic cytoplasm. Staining for Alpha-1 AntiChymotrypsin (AACT), TTF-1 and PAS was diffusely positive, and S-100 staining was focally positive in the tumor cells. CD34, CK, EMA, GFAP and HMB45 staining were negative. The Ki-67 index was < 1%. According to these findings, the tumor was diagnosed as a symptomatic granular cell tumor of the neurohypophysis. We suggest that identifying the location of the tumor with imaging is helpful for understanding the granular cell tumor of the neurohypophysis. Prompt diagnosis and treatment are critical for patients.

Extent of surgical resection and tumor size predicts prognosis in granular cell tumor of the sellar region

BACKGROUND

Rarely, granular cell tumor (GCT) occurs in the sellar region. The natural history of this clinical entity is not well known. This study sought to determine the clinical features and long-term outcome of GCT of the sellar region.

METHODS

Institutional databases, the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database, and PubMed/EMBASE were searched for GCT of the sellar region. Patient-level data were extracted where available, including age, sex, symptoms, tumor size and location, presumed diagnosis, surgical approach and result, subtotal resection (STR) and gross-total resection (GTR), use of radiation, and outcome. The primary endpoints of recurrence and survival were determined.

RESULTS

A total of 141 cases were analyzed. The mean age at diagnosis was 48.9 (SD 15.3) with a female predominance (sex ratio 1.49:1). Almost all patients experienced either or both neurological and endocrine symptoms. The most common pre-operative diagnosis was pituitary adenoma. Approximately 60% of patients were treated with surgery, 57.7% with a craniotomy, and 39.7% with a transsphenoidal approach. The 5-year overall survival (OS) was 84.7% (standard error, SE 4.2). Patients with tumors less than 2.5 cm experienced a greater 5-year OS (100.0%) than patients with tumors 2.5 cm or larger (74.0%, SE: 11.7), (Mantel-Cox, p = 0.024). GTR resulted in a greater 5-year OS (95.7%, SE 4.3) than STR (88.8%, SE 5.5) and no surgery or biopsy alone (75.0%, SE 15.3) (Mantel-Cox, p = 0.016). The use of radiation therapy did not improve OS. The 5-year progression-free survival rate was 80.8% (SE 9.2).

CONCLUSIONS

Granular cell tumor of the sellar region is a relatively benign neoplasm with neurological and endocrine clinical manifestations. Surgical resection is appropriate for management. Tumor size and extent of resection influence overall survival.

Update on hypophysitis and TTF-1 expressing sellar region masses

This article reviews recent literature on sellar region masses that most closely mimic nonsecretory pituitary adenomas: hypophysitis, pituicytoma, spindle cell oncocytoma, and granular cell tumor of neurohypophysis. Even today, these four entities often cannot be confidently distinguished from each other clinically or by preoperative neuroimaging features. Thus, they often come to biopsy/surgical resection and require tissue confirmation of diagnosis. Causes of secondary and primary hypophysitis will be discussed, including two newly described types, IgG4 plasma cell hypophysitis and hypophysitis caused by anti-cytotoxic T-lymphocyte antigen 4 antibody therapy for cancer. For the neoplastic conditions, emphasis will be placed on literature that has emerged since these entities were first codified in the 2007 World Health Organization fascicle. The finding that immunohistochemical staining for thyroid transcription factor-1 is shared by pituicytoma, spindle cell oncocytoma, and granular cell tumor of neurohypophysis suggests common lineage and explains why histological overlap can be encountered. We incorporate our own experiences over the last 30 years from two referral institutions with specialty practices in pituitary region masses.

Pituicytoma, spindle cell oncocytoma, and granular cell tumor: clarification and meta-analysis of the world literature since 1893

BACKGROUND AND PURPOSE

Pituicytoma, SCO, and GCT are poorly understood entities with confusing nomenclature and undetermined imaging characteristics. Our purpose was to confirm published cases of pituicytoma, SCO, and GCT with the newest 2007 World Health Organization criteria and elucidate imaging findings that distinguish these tumors from common entities such as pituitary adenoma.

MATERIALS AND METHODS

A literature search identified 145 published cases (81 GCTs, 48 pituicytomas, and 16 SCOs). Case diagnoses were blindly reviewed by a neuropathologist according to the latest WHO criteria, resulting in 112 pathologically documented cases (64 GCTs, 35 pituicytomas, and 13 SCOs). Imaging illustrations from proved cases were reviewed to determine location, configuration, attenuation and signal intensity, and enhancement characteristics.

RESULTS

Only pituicytomas presented as purely intrasellar lesions (7/33). Most GCTs were purely suprasellar (28/45). All SCOs were both intra- and suprasellar (13/13). Twenty-five percent of pituicytomas (6/22) and GCTs (7/30) appeared separate from the pituitary gland. All SCOs were infiltrating. Seventy-nine percent of entities appeared isointense to brain on T1-weighted image (34/43). Seventy-four percent of pituicytomas enhanced homogeneously (14/19). Twelve of 23 GCTs and 5/7 SCOs enhanced heterogeneously. Most GCTs were hyperattenuated to brain on CT (18/20). Eleven of 13 cases enhanced homogeneously. Visual disturbances were common symptoms for all entities (67/112). Diabetes insipidus was rare (4/112).

CONCLUSIONS

Pituicytoma may be considered for purely intrasellar masses that are clearly separate from the pituitary gland. GCT should receive consideration for purely suprasellar lesions that are hyperattenuated to brain on CT. SCO should be considered for infiltrating pituitary masses with a mixed intra- and suprasellar location. A history of diabetes insipidus helps to exclude these tumors.

Cystic granular cell tumor mimicking Rathke cleft cyst

Symptomatic granular cell tumors of the neurohypophysis are a rarely reported entity. To the authors' knowledge, they report the first fully described case of a symptomatic granular cell tumor with a large cystic component. A 31-year-old woman presented with headaches and visual complaints with imaging findings confirming a cystic sellar and suprasellar mass. The lesion was resected, and histological examination confirmed the diagnosis. The literature has shown that granular cell tumors are rarely reported as being symptomatic but may actually be a fairly common finding in autopsy studies. The authors review the literature with a specific focus on radiographic findings in patients with symptomatic granular cell tumors.