Brain Pathology Case of the Month - October 2015

Contributed by Fabien Forest, MD1, François Casteillo, MD1, Romain Manet, MD2, Claire Boutet, MD, PhD3, Cyril Habougit, MD1, Violaine Yvorel, MD1, Robert Duthel, MD2, Michel Péoc’h, MD, PhD1
Departments of 1Pathology, 2Neurosurgery, 3Radiology of CHU de Saint Etienne, Hôpital Nord, 42055 Saint Etienne CEDEX2. France


A 48 years-old patient without significant medical history or without bleeding disorder is addressed to our institution for acute headache and bitemporal hemianopsia. No hormonal secretion was detected, and the patient had a pituitary insufficiency with loss of libido, diffuse hair loss, asthenia and slowing. An MRI showed a 47mm pituitary lesion occupying the sella turcica with central necrosis. This lesion was hypointense in T1 sequence, enhanced with gadolinium injection and hyperintense in T2 sequence (Fig.1). Then, a transsphenoidal excision surgery was decided. A first surgery was performed, but the resection of the tumor lead to an extensive bleeding and the tumor could not be resected entirely. Three days later, because of incomplete resection a second excision procedure was decided leading to an extensive bleeding and a subtotal surgical resection. The visual symptoms of the patient improved quickly after the surgery.


Under light microscopy, histological examination showed a highly cellular tumor, with spindle cells and scattered highly pleomorphic cells (Figs. 2 & 3). The cytoplasm was oncocytic: eosinophilic and granulose. Despite the highly cellular pleomorphism, the mitosis count did not show any mitosis per 10 high power fields. Small areas of necrosis were found. Few nuclear pseudo-inclusions were seen (Fig. 4). The vascular network was highly developed, harboring either thin or branched capillaries, either large with fibrous vessel wall (Fig. 2). Scattered lymphoid infiltrates were seen within the solid part of the tumor, but without peri-vascular tropism (Fig. 5). Perl's iron stain showed iron deposit. No rosette or pseudorosette was found. An immunochemical staining showed a diffuse nuclear staining for TTF-1 (Fig. 6) and BAF47, an intense and diffuse cytoplasmic staining for S 100 protein and Galectin3 (Fig. 7), and a patchy but intense staining for EMA (Fig. 8). No labeling by anti-KL1, Chromogranin A, CD34, cMET, GFAP, p40 and pituitary hormones was seen. Proliferation index evaluated on Ki67 was about 4% in the most proliferative area.

Electron microscopy imaging showed cytoplasmic accumulation of swollen mitochondria (Fig. 9).


International Society of Neuropathology