Brain Pathology Case of the Month - March 2002


On permanent sections there were multiple enlarged coalescent lymphoid follicles with an onion skin appearance of tight concentric layering of small, uniform mature lymphocytes at the periphery, arranged in a targetoid fashion with broad mantle zones and relatively small germinal centers (Figure 3). The germinal centers of variable size included hyalinized blood vessels. Lollipop follicles were seen. The interfollicular stroma showed numerous hyperplastic collagenized capillaries within an inflammatory background. However, the perinodal soft tissue was replaced by numerous inflammatory cells, primarily lymphocytes. Within this lesion, at one edge, the epineurium of a nerve ganglion and portions of a nerve were ruptured and fragmented (Figure 4) and the vessel walls are highlighted by azocarmine stain (Figure 5). The specimen labeled "proximal root neurofibroma" consisted of a normal nerve with focal perivascular inflammatory infiltrate. Grocott stains for fungi and AFB stains for mycobacterium were negative.


International Society of Neuropathology