Psammomatous melanotic schwannoma - a rare neck lump.

This case report discusses a cervical psammomatous melanotic schwannoma - a rare form of peripheral nerve sheath tumour - which may be highly vascular and is often associated with the Carney complex. Significant intraneural bleeding, which was encountered intraoperatively, was controlled successfully with a gelatine-based thrombin haemostatic agent (Floseal®, Baxter International, Deerfield, IL, USA) without complication.

Choroidal melanoma in a dog.

A 7-year-old male Great Dane dog was presented with blindness and a hemorrhagic retinal detachment in the right eye. Ocular ultrasonography revealed a conical-shaped mass in the posterior segment that protruded into the vitreous cavity. Histologic examination of the enucleated eye revealed a heavily-pigmented melanocytoma arising from the choroid lateral to the optic disc.

Waveform analysis and reproducibility of visual-evoked potentials in dogs.

Visual-evoked potentials (VEP) and electroretinograms (ERG) were recorded from 10 normal light-adapted adult dogs, using a 3 x 5 matrix of light-emitting diodes as a stimulator. Visual-evoked potentials were recorded from 4 scalp electrodes overlying cortical areas, whereas electroretinographic activity was recorded by 2 scalp electrodes placed near the eye and by a conjunctivally placed electrode. The waveform of the VEP consisted of 3 major positive waves (P1 through P3), with peak latencies in the 20- to 70-ms range. Waveform reproducibility was assessed by comparing peak latencies from VEP recorded on 2 separate days approximately 1 week apart. The peak latencies for P1 through P3 did not differ (P greater than or equal to 0.05) between first and second recording sessions. To substantiate the postretinal origin of VEP, recordings were made before and after unilateral optic nerve transsections in 4 dogs. Electroretinograms were also measured before and after surgery to assess the integrity of the retina. Postsurgically, VEP were absent when the eye on the surgically treated side was stimulated. Stimulation of the contralateral eye induced VEP with the same waveform shape, but latencies were slightly prolonged (P less than or equal to 0.05) compared with presurgical recordings. The only effect of optic nerve transsection on the ipsilateral ERG was a prolongation (P less than or equal to 0.05) of the b-wave. However, when postsurgical ERG values were compared with those from the intact side after surgery, there were no differences.