Acromegaly associated with a granular cell tumor of the neurohypophysis: a clinical and histological study

Abstract

Acromegaly is usually caused by a growth hormone (GH)-secreting pituitary adenoma, and hypersecretion of GH-releasing hormone (GHRH) from a hypothalamic or neuroendocrine tumor accounts for other cases. The authors report on the unusual association of acromegaly with a granular cell tumor of the neurohypophysis. A 42-year-old woman with a 10-year history of acral enlargement, headache, and menstrual abnormalities was referred to our department for a suspected GH-secreting pituitary adenoma. The patient's basal GH levels were mildly elevated at 4.8 microg/L, were not suppressed in response to an oral glucose tolerance test, and increased paradoxically after administration of thyrotropin-releasing hormone. The patient's insulin-like growth factor-1 (IGF-1) level was elevated at 462 microg/L, whereas a magnetic resonance image of the sella turcica revealed an intra- and suprasellar lesion that was compatible with a diagnosis of pituitary adenoma. A transsphenoidal approach to remove the lesion, which was mainly suprasellar, was successful during a second operative attempt, resulting in the clinical and biochemical regression of the patient's acromegaly. Four months postoperatively, the patient's basal GH level was 0.9 microg/L and her IGF-1 level was 140 microg/L. Histological analysis of the operative specimen demonstrated a granular cell tumor of the neurohypophysis, which when stained proved negative for pituitary hormones and GHRH. This case represents the first reported association between a granular cell tumor of the neurohypophysis and acromegaly. Granular cell tumor of the neurohypophysis could be added to the restricted list of neoplastic causes of acromegaly secondary to hypersecretion of a GH-releasing substance.

Granular cell tumor of the neurohypophysis: report of a case with unusual age presentation

“…A similar picture was reported by Losa et al [10] regarding GH. These authors suggested that a GCT could secrete a GH precursor, thus explaining the acromegaly presentation of their patient.…”

A Large Sellar Granular Cell Tumor in a 21-year-old Woman

“…In one case, the 8-year-old boy showed signs of precocious puberty [4]. In the second case, the 42-yearold woman was diagnosed with acromegaly [11]. The authors suggested that the tumor produced a GH release stimulating hormone [10].…”

Granular cell tumour of the neurohypophysis: an unusual cause of hypopituitarism

“…Since then, many autopsy series have revealed a high prevalence of granular cell tumourlettes in the general population, particularly in the elderly (6.7–17%) (4, 6). Although these small tumours are generally benign, non-secreting, slow growing and arising in the sellar region, malignant variants have also been described (7). In the majority of cases, they are incidental findings at the time of autopsy, being symptomatic cases extremely rare.…”

“…Presenting symptoms include insidious onset of visual disturbances in up to 90% of the cases, headaches and endocrine changes in approximately 50%: amenorrhea, galactorrhea, infertility, impotence and weight fluctuations (4). Signs of hypopituitarism or hyperprolactinaemia are the most frequent findings; however, a case report of acromegaly has been described in the literature (7). Radiological findings are rather nonspecific and may share features of other CNS lesions such as meningioma, pituitary adenoma, chordoma or teratoma.…”