Final Diagnosis -- Spindle Cell Oncocytoma of the Adenohypophysis (WHO Grade I)


Spindle cell oncocytoma of the adenohypophysis (WHO Grade I)


Spindle cell oncocytoma is a recently described entity and recognized by the actual WHO classification (9,12). The clinical presentation is not specific and depends on the tumor mass syndrome or pituitary insufficiency since this tumor has no hormonal secretion. In one case epistaxis was the revealing symptom (8). The distinction of spindle cell oncoytoma of the adenohypophysis from other pituitary solid tumors on clinical and imaging is difficult because the imaging features are not specific (12,11,7). Intratumoral hemorrhage of varying ages can be encountered and the imaging aspect be more difficult to interpret (1).The diagnosis is histological and often relies on transphenoidal resection samples (7). Neuropathological examination is shows spindle cells, with sometimes pleomorphic nuclei. Rare nuclear pseudo-inclusions, like in our case and similar to those encountered in meningiomas can be seen (15). Such as other rare lesions of the central nervous system, spindle cell oncocytoma can be misdiagnosed as schwannoma (7,6). Pituitary spindle cell oncocytoma is highly vascular, which like in our case can lead to incomplete resection (11,7,3,4). Since the quality of the resection seems to be an important parameter for recurrence-free survival, although an allowed grade I, the prognosis of these tumors could be worsened (11). Immunohistochemical study shows a labeling of tumor cells by anti-Vimentin, EMA, S-100 protein, galectin3 and TTF-1 (13). There is no GFAP, chromogranin A, cytokeratin or pituitary hormone expression (13). Proliferation index is usually low, but in one report it is reported up to 20% and associated with necrosis raising the possibility of a more aggressive feature (8). No recurring mutations or characteristic molecular hallmark has yet been described in these tumors (10). The main differential diagnoses are pituicytoma, granular cell tumor of the neurohypophysis, oncocytic meningioma, oncocytic adenoma, solitary fibrous tumor, schwannoma and paraganglioma. Spindle cell oncocytoma, pituicytoma and granular cell tumor of the neurohypophysis differential diagnoses remain difficult (2). Although defined as separate entities in the actual WHO classification of tumors, some authors raise the possibility that spindle cell oncoytoma, pituicytoma and granular cell tumors could represent the same spectrum of tumor (10).

The treatment relies on complete surgical excision. Radiotherapy efficiency is debated and requires further study to assess its role in spindle cell oncocytoma treatment (3,5). It was first though that spindle cell oncocytoma could derivate from folliculostellate cells based on immunohistochemical (Galectin 3 expression) and ultrastructural features (12,14). Recently, it has been suggested that spindle cell oncocytoma and granular cell tumor of pituitary may be variants of pituicytoma based on ultrastructural features and immunohistochemical staining (diffuse TTF1 staining) (10). Because TTF-1 is not expressed by folliculostellate cells but is expressed by pituicytes, Mete et al. suggest that these tumors could indicate a common pituicyte lineage (10). The authors propose the terminology "oncocytic pituicytomas" and "granular cell pituicytomas" for spindle cell oncocytoma of the adenohypophysis, granular cell tumors of the neurohypophysis and pituicytoma (10).

This presentation must be known from neurosurgeons and pathologists since massive intraoperative bleeding can occur. Extensive bleeding can lead to incomplete resection. Because complete resection seems to be a major prognosis factor although an allowed WHO grade I, this should be integrated in the managing of this rare tumor.


  1. Borges MT, Lillehei KO, Kleinschmidt-DeMasters BK (2010) Spindle cell oncocytoma with late recurrence and unique neuroimaging characteristics due to recurrent subclinical intratumoral bleeding. J Neurooncol 101:145 154.
  2. Covington MF, Chin SS, Osborn AG (2011) Pituicytoma, Spindle Cell Oncocytoma, and Granular Cell Tumor: Clarification and Meta-Analysis of the World Literature since 1893. Am J Neuroradiol 32:2067 2072.
  3. Dahiya S, Sarkar C, Hedley-Whyte ET, Sharma MC, Zervas NT, Sridhar E, et al (2005) Spindle cell oncocytoma of the adenohypophysis: report of two cases. Acta Neuropathol 110:97 99.
  4. Demssie YN, Joseph J, Dawson T, Roberts G, Carpentier J, Howell S (2009) Recurrent spindle cell oncocytoma of the pituitary, a case report and review of literature. Pituitary 14:367 370.
  5. Farooq MU, Bhatt A, Chang HT (2008) Teaching NeuroImage: Spindle cell oncocytoma of the pituitary gland. Neurology 71:e3 e3.
  6. Forest F, N'guyen AT, Fesselet J, Metellus P, Bouvier C, de Paula AM, et al (2014) Meningeal Rosai-Dorfman disease mimicking meningioma. Ann Hematol 93:937-40
  7. Fujisawa H, Tohma Y, Muramatsu N, Kida S, Kaizaki Y, Tamamura H (2012) Spindle cell oncocytoma of the adenohypophysis with marked hypervascularity. Case report. Neurol Med Chir 52:594 598.
  8. Kloub O, Perry A, Tu P-H, Lipper M, Lopes MBS (2005) Spindle cell oncocytoma of the adenohypophysis: report of two recurrent cases. Am J Surg Pathol 29:247 53.
  9. Louis DN, Ohgaki H, Wiestler OD, Cavenee WK, Burger PC, Jouvet A, et al (2007) The 2007 WHO Classification of Tumours of the Central Nervous System. Acta Neuropathol 114:97 109.
  10. Mete O, Lopes MB, Asa SL (2013) Spindle cell oncocytomas and granular cell tumors of the pituitary are variants of pituicytoma. Am J Surg Pathol 37:1694 9.
  11. Ogiwara H, Dubner S, Shafizadeh S, Raizer J, Chandler JP (2011) Spindle cell oncocytoma of the pituitary and pituicytoma: Two tumors mimicking pituitary adenoma. Surg Neurol Int. 2:116.
  12. Roncaroli F, Scheithauer BW, Cenacchi G, Horvath E, Kovacs K, Lloyd RV, et al (2002) Spindle Cell Oncocytoma'of the Adenohypophysis: A Tumor of Folliculostellate Cells? Am J Surg Pathol 26:1048 55.
  13. Singh G, Agarwal S, Sharma MC, Suri V, Sarkar C, Garg A, et al (2012) Spindle cell oncocytoma of the adenohypophysis: Report of a rare case and review of literature. Clin Neurol Neurosurg 114:267 271.
  14. Vajtai I, Beck J, Kappeler A, Hewer E (2011) Spindle cell oncocytoma of the pituitary gland with follicle-like component: organotypic differentiation to support its origin from folliculo-stellate cells. Acta Neuropathol 122:253 258.
  15. Vajtai I, Sahli R, Kappeler A (2006) Spindle cell oncocytoma of the adenohypophysis: Report of a case with a 16-year follow-up. Pathol - Res Pract 202:745 750.


The authors would like to thank Mrs Nathalie Chazalmartin, Mr Christophe Forest, Dr Lionel Chabanol, Dr Cyril Richard, Mrs Martine Laval and Centre de Microscopie Electronique Stéphanois for their help in the preparation of this manuscrip

Contributed by Fabien Forest, MD, François Casteillo, MD, Romain Manet, MD, Claire Boutet, MD, PhD, Cyril Habougit, MD, Violaine Yvorel, MD, Robert Duthel, MD, Michel Péoc’h, MD, PhD

Case IndexCME Case StudiesFeedbackHome