Brain Pathology Case of the Month - September 2007

Contributed by Frauke Neff, MD1; Gregor Weirich, MD2; Peter Herzog, MD3; Heinz Schlöser, MD4; Claudia Kiebach, MD4 and Jügen Schlegel, MD1
1Abteilung für Neuropathologie, Institut für Allgemeine Pathologie und Pathologische Anatomie, Technische Universität München
2Institut für Allgemeine Pathologie und Pathologische Anatomie, Technische Universität München
3Neurochirurgische Klinik, Klinikum Augsburg
4Radiologische Praxis, Augsburg


A 35 year old woman was admitted to our hospital with symptoms and signs of acromegaly that started one year earlier. Physical examination detected clubbing of her fingers, enlargement of her jaws, a carpal tunnel syndrome along with joint and neck pain. Laboratory findings showed hypothyroidism, secondary hypogonadism, diabetes mellitus and anemia. Cranial MRI revealed an intra- and suprasellar mass lesion with radiological signs of a chiasma syndrome. She was treated with a somatostatin therapy. Although the clinical symptoms improved over the next three months, Insulin like Growth Factor-1 levels ( a marker for acromegaly) continued to be at pathological levels. The patient therefore underwent a transphenoidal resection of the intrasellar mass.


Cranial MRI revealed an intra- and suprasellar mass lesion 18mm in diameter with direct contact to the optic chiasma. The pituitary stalk was thickened and enhanced after the intravenous administration of gadolinium contrast agent (Figure 1).


The tumor presented two macroscopic aspects: One part was a crumbly, hard mass and the other part was a soft, spongy mass. Consistent with the macroscopic aspect, the histopathology revealed two components, a tumorous and an inflammatory lesion:

The major part represented residual acini of adenohypophysial cells surrounded by an intact reticulin fiber network. Within the pituitary tissue scattered masses of elongated, sometimes spindle shaped histiocytic cells with pale eosinophilic cytoplasm and kidney shaped, slightly basophilic nuclei appeared. The histiocytes were surrounded by various numbers of lymphocytes and plasma cells. Multinucleated giant cells could also be found, scattered among inflammatory cells. There was, however, no caseous necrosis (Figure 2).

The minor part of the lesion consisted of sheets of chromophobic cells with slightly granulated cytoplasm and few cytoplasmic juxtanuclear vacuoles (Figure 3). These cells showed large nuclei with notable polymorphism and prominent nucleoli. There were some capillary proliferations and few swollen reticulin fibers. The immunohistochemistry using AE1/AE3 anti cytokeratin antibodies revealed a focal cytokeratin expression with very sparse fibrous bodies (Figure 4). There was also a weak positive immunoreactivity human growth hormone alpha human chorionic gonadotropin in some cells.

Due to the granulomatous character of the major part of this lesion, Ziehl-Neelsen (Figure 5) and silver stains were performed, but neither of them showed acid-fast (Figure 5, inset) or spiral bacteria. A special procedure was then done to make the diagnosis.


International Society of Neuropathology