Low power shows pink stromal background which is relatively low cellularity punctuated by larger cells indicative of ganglion cells.
The Schwannian stroma is composed of pink fibrillary material and very bland spindled nuclei.
There are many Schwann cells and mature ganglion cells in clusters. Nissl substance is easy to recognize. Care must be taken to look for neuroblastomatous elements and rule out intermixed ganglioneuroblastoma (read below).
Stromal calcifications are not uncommon.
Neuroblastic tumors are of neural crest origin and can arise in the adrenal gland or other locations where sympathetic ganglia exist such as the posterior mediastinum or retroperitoneum. From the least mature to the most mature, the neuroblastic tumors are ganglioneuromas, ganlgioneuroblastomas and neuroblastomas. The way to determine which category the tumor falls into depends on two factors: (1) amount of Schwannian stroma and (2) presence of mature ganglion cells.
Both ganglioneuroblastomas and ganglioneuromas have greater than 50% Schwannian stroma whereas neuroblastomas have less than 50% Schwannian stroma. The difference between ganglioneuroblastomas and ganglioneuromas is the amount of neuroblasts. Ganglioneuromas have very few neuroblasts and mostly mature or maturing ganglion cells.
This might be too much information, but ganglioneuromas are further divided into mature and maturing. Maturing ganglioneuromas have scattered neuroblasts and ganglion cells, whereas mature ganglioneuromas have only mature ganglion cells and no neuroblasts. Why do we care at all? Well, one most differentiate between maturing ganglioneuromas and "intermixed ganglioneuroblastomas", and the latter has malignant potential. In intermixed ganglioneuroblastomas, there are islands or clusters of neuroblasts, differentiating neuroblasts and ganglion cells (versus singly dispersed cells in maturing ganglioneuromas). Personally, this gives me a migraine and it might be best to send it for consult.
Neuroblastoma and nodular ganglioneuroblastomas are further subclassified into prognostic groups by a complex interplay of factors including age of patient (less than 1.5 years of age is favorable), mitosis-karyorrhexis index (calculated by the number of mitotic figures and karyorrhectic bodies per 5000 cells), favorable histology (abundant Schwannian stroma, maturing ganglion cells) and cytogenetics. Greater than 10 copies of n-MYC indicates a more aggressive tumor. Loss of chromosome 1p, 14q deletion, 11q deletion and gain of 17q are also unfavorable.
Tumors are usually asymptomatic, allowing them to grow to substantial size. They are rather slow-growing.
→Greater than 50% Schwannian stroma places you into the ganglioneuroblastoma or ganglioneuroma category.
→Rare or absent neuroblasts (and presence of mature or maturing ganglion cells) renders the diagnosis of ganlgioneuroma.