Brain Pathology Case of the Month - August 2001

DIAGNOSIS:

Atypical granular cell tumor of the neurohypophysis.

DISCUSSION:

"Granular cell tumor" (GCT) is a purely descriptive term for a histogenetically heterogeneous group of neoplasms. "Peripheral" GCTs are either congenital (congenital epulis) or, more frequently, develop during later life. Intracranial GCTs are usually found in the posterior hypophysis, and only rarely in the cerebral hemispheres or leptomeninges.

Symptomatic GCTs of the neurohypophysis are rare neoplasms. Only 42 reports were found by Schaller et al. (8). Additionally, we identified 5 further instances, including our own case (6, 9, 10). There is a wide range of age distribution. Most frequently the tumors are diagnosed between 30 and 60 years of age, with a 2:1 predominance of females.

GCTs of the neurohypophysis are usually regarded as slowly growing, well-circumscribed benign tumors. As a rule, uncharacteristic clinical symptoms of a hypophyseal neoplasm develop insidiously (1). To the best of our knowledge, only five cases with short duration of symptoms have been described previously (2, 3, 4, 8, 11). In our case, only four weeks elapsed between the onset of symptoms and surgery.

The tumor showed a number of peculiarities: First, it infiltrated the optic chiasm. Histologically, there was remarkable cellular and nuclear polymorphism, which to date has been mentioned in neurohypophyseal GCTs only by Shuangshoti et al. (10). As mitoses were very rare and necroses or vascular proliferations did not occur, there were no clear signs of malignancy. To obtain further insight into the biology of the tumor, we performed a number of immunohistochemical analyses. Positivity of tumor cells were for p53 and bcl-2 as well as negative results concerning bax may correlate with the relatively aggressive behavior of this GCT, and its rapid recurrence.

The biology of GCTs is poorly understood. At autopsy, small neoplasms of the posterior lobe of the pituitary gland are not uncommon as an incidental finding. In systematic postmortem histological studies, micronodules of granular cells (tumorettes) were registered in up to 17% of unselected adult autopsy cases (2). Evidently, these lesions grow very slowly for a long time, and the majority never produce clinical symptoms. In contrast to "peripheral" counterparts, overtly malignant GCTs of the posterior hypophysis have not been reported. Our observation, in the context of cases reported in the literature, shows that the natural course of GST of the neurohypophysis may not be as favorable as is generally believed today (8, 11). Whether histological atypia influences the outcome of the neoplastic disease needs further investigation.

References:

  1. Asa LS (1998) Tumors of the pituitary gland. In: Atlas of Tumor Pathology, pp 159-160, 3rd ed., fasc. 22, Armed Forces Institute of Pathology, Washington
  2. Boecher-Schwarz HG, Fries G, Bornemann A, Ludwig B, Perneczky A (1992) Suprasellar granular cell tumor. Neurosurgery 31: 751-754
  3. Cone L, Srinivasan M, Romanul FCA (1990) Granular cell tumor (choristoma) of the neurohypophysis: two cases and a review of the literature. Am J Neuroradiol 11: 403-406
  4. Graziani N, Dufour H, Figarella-Branger D, Bouillot P, Grisoli F (1995) Suprasellar granular-cell tumour, presenting with intraventricular haemorrhage. Br J Neurosurg 9: 97-102
  5. Liwnicz BH, Liwnicz RG, Huff JS, McBride BH, Tew JM Jr (1984) Giant granular cell tumor of the suprasellar area: immunocytochemical and electron microscopic studies. Neurosurgery 15: 246-251
  6. Moriyama E, Matsumoto Y, Meguro T, Mano S (1996) Suprasellar granular cell tumor. Neurol Med Chir (Tokyo) 36: 237-240
  7. Radhakrishnan VV, Misra BK, Rout D (1997) Granular cell tumour (choristoma) of the neurohypophysis - a report of two cases. Indian J Pathol Microbiol 40: 71-74
  8. Schaller B, Kirsch E, Tolnay M, Mindermann T (1998) Symptomatic granular cell tumor of the pituitary gland: case report and review of the literature. Neurosurgery 42: 166-171
  9. Shanklin WM (1953) The origin, histology and senescence of tumorettes in the human neurohypophysis. Acta anat (Basel) 18: 1-20
  10. Shuangshoti S, Chantra K, Navalitloha Y, Charoonwatanalaoha S, Shuangshoti S (1998) Atypical granular cell tumor of the neurohypophysis: a case report with review of the literature. J Med Assoc Thai 81: 641-646
  11. Wilson CB (1992) Comment to Boecher-Schwarz et al. (2)

Contributed by Silke Vogelgesang , Michael H. Junge, Jens Pahnke, Michael R. Gaab, Rolf W. Warzok

International Society of Neuropathology