The international classification has stipulated that tumors having prominent Schwannian stromal development occupying more than 50% of the tumor tissue are upgraded to this category. Tumor histology is consistent with a transition to the full differentiation/maturation of ganglioneuroma (see below), but the process is not complete, as evidenced by scattered "residual" microscopic foci where neuroblastic cells in various stages of differentiation as well as varying numbers of maturing ganglion cells are found in the background of neuropil (Fig. 8.1e).
Ganglioneuroma, Maturing Subtype (Fig. 8.1 f): Tumor of this subtype was previously named "gan-glioneuroblastoma, well differentiated" in the original Shimada classification. Some of the neuroblastic components appear to be on their way to fully mature ganglion cells and have appearances of differentiating neuroblasts and/or maturing ganglion cells.
Ganglioneuroma, Mature Subtype (Fig. 8.1 g): Tumor in this subtype is composed of fully developed Schwannian stroma and mature ganglion cells. Those mature ganglion cells are surrounded by satellite cells. Mature non-myelinating Schwann cells, the dominating component of tumor, characteristically form multiple fascicles covered with perineurial cells.
Tumors categorized as either ganglioneuroblastoma, intermixed, or ganglioneuroma have an elastic consistency, and their cut surfaces are always tan-yellow and homogenous with or without fibrous bands.
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