Acromegaly with GH-positive neuronal choristoma and pituitary adenoma: A case of PANCH tumour.
Leong Quah, Ute Pohl, Jonathan Pollock & James Ahlquist
Neurosurgery & Neuropathology, Queen’s Hospital Romford and Endocrinology, Southend Hospital, Essex.
Pituitary Adenoma with Neuronal Choristoma (PANCH tumour), is a very rare form of pituitary pathology composed of a mixed pituitary adenoma/gangliocytoma. We describe a patient with acromegaly who had evidence of growth hormone synthesis in the neuronal component of a PANCH tumour.
A 55 year old woman was found to have facial features of acromegaly, confirmed biochemically: basal GH 13.56 ng/mL, GTT nadir 8.87 ng/mL, IGF1 97.2 nmol/L (9-40). Pituitary function was otherwise normal. MRI revealed a 25 mm mass in the pituitary fossa, with cavernous sinus extension; there were no unusual radiological features. She underwent endoscopic trans-sphenoidal surgery, during which the tumour was noted to have an unusual, slightly fibrous consistency. Intra-operative histological examination suggested that the tumour may be a ganglioglioma. Following surgery pituitary function remained intact: formal endocrine reassessment is awaited.
Histological examination of the tumour revealed islands of pituitary adenoma embedded in a neuropil substrate made up of ganglion-like cells, some of which showed dysplastic features (cytomegaly, binucleation and dysmorphism). Ganglion cells were embedded within both the adenoma and the neuroglial tissue. Immunohistochemistry confirmed that the adenoma cells were positive for GH & prolactin, with scattered cells positive for TSH also. In addition, a subpopulation of the ganglion cells also showed strong staining for prolactin, and weak staining for GH, TSH and ACTH. Both pituitary adenoma and ganglion cells were strongly positive for synaptophysin; chromogranin only stained rare small cells. Glial fibrillary acid protein staining was generally negative throughout. The neural tissue features were described as typical of a neuronal choristoma.
The combination of a pituitary adenoma with neuronal choristoma (PANCH) is a very rare form of pituitary pathology. The finding of neuronal tissue expressing GH and prolactin in association with a somatotroph adenoma is intriguing. The pathogenesis of this phenomenon is not clear. The combination of two distinct GH & prolactin-positive cell types, pituitary adenoma and gangliocytoma, occurring within a single tumour, suggests that the neuronal cell population may have arisen as a result of neuronal differentiation within a pituitary adenoma.