Primary extragastrointestinal stromal tumor of the pleura: report of a unique case with genetic confirmation.

Gastrointestinal stromal tumors (GISTs), the most common mesenchymal neoplasms of the tubular gastrointestinal tract, usually originate in the wall of the stomach or small intestine. Most GISTs harbor oncogenic mutations in either the KIT or platelet-derived growth factor receptor alpha (PDGFRA) tyrosine kinase receptor genes and show differentiation along the lines of the interstitial cells of Cajal. Rarely, GISTs arise primarily in the omentum, mesentery, or retroperitoneum, at which sites they are referred to as "extragastrointestinal stromal tumors" (EGISTs). However, primary intrathoracic GIST arising in the pleura or lung has not been previously reported. We describe herein, a 62-year-old male who presented with a pleural-based mass unrelated to the esophagus that was morphologically typical of a spindle-cell GIST, showing strong immunoreactivity for KIT and DOG1, and harboring an exon 11 mutation in KIT. Ten years after resection, the tumor recurred as multiple masses in the pleura and mediastinum and was marginally reexcised. The patient was then treated with adjuvant imatinib mesylate with no evidence of further recurrences 13 months later. This seems to be the first EGIST arising above the diaphragm. This case shows a potential diagnostic pitfall with therapeutic consequences.

Perisaccadic parietal and occipital gamma power in light and in complete darkness.

Our objective was to determine perisaccadic gamma range oscillations in the EEG during voluntary saccades in humans. We evaluated occipital perisaccadic gamma activity both in the presence and absence of visual input, when the observer was blindfolded. We quantified gamma power in the time periods before, during, and after horizontal saccades. The corresponding EEG was evaluated for individual saccades and the wavelet transformed EEG averaged for each time window, without averaging the EEG first. We found that, in both dark and light, parietal and occipital gamma power increased during the saccade and peaked prior to reaching new fixation. We show that this is not the result of muscle activity and not the result of visual input during saccades. Saccade direction affects the laterality of gamma power over posterior electrodes. Gamma power recorded over the posterior scalp increases during a saccade. The phasic modulation of gamma by saccades in darkness--when occipital activity is decoupled from visual input--provides electrophysiological evidence that voluntary saccades affect ongoing EEG. We suggest that saccade-phasic gamma modulation may contribute to short-term plasticity required to realign the visual space to the intended fixation point of a saccade and provides a mechanism for neuronal assembly formation prior to achieving the intended saccadic goal. The wavelet-transformed perisaccadic EEG could provide an electrophysiological tool applicable in humans for the purpose of fine analysis and potential separation of stages of 'planning' and 'action'.