April 26, 2017

DIPG histopathology and more about

http://journal.frontiersin.org/article/10.3389/fonc.2015.00147/full

Recent studies...have provided a breadth of evidence highlighting the unique molecular genetics and epigenetics of this cancer, distinguishing it from both adult and pediatric cerebral high-grade astrocytomas. 

DIPG Histopathology

Diffuse intrinsic pontine glioma is a heterogeneous disease, and represents a varied histological spectrum. These tumors are very diffuse and often involve adjacent brain structures beyond the pons.

Several studies report it spreading beyond pons...in as many as one-third of DIPG, tumor cells found as far rostrally as the FRONTAL LOBE (!)

A review...on 108 biopsies from 13 studies, including 37 AA (WHO grade III), 27 GBM(WHO grade IV), 22 LGA (WHO grade II), 3 anaplastic oligoastrocytomas (WHO grade III), and 19 tumors with “not further specified” or undefined characterization.

Data suggest that WHO grade III AA- anaplastic astrocytoma - are the most common histological entity in brainstem glioma; however, autopsy based histopathological studies report WHO grade IV GBM to be the most common histology.

Of the 33 pediatric patients, 29 were reported to be GBM and 4 with anaplastic astrocytoma histology.

Abother source reported 42 GBM, 18 anaplastic astrocytoma, 8 low-grade astrocytoma, and 2 with features of primitive neuroectodermal tumor (PNET, WHO grade IV).

Importantly, reginal differencies WITHIN ONE DIPG specimen, can bias biopsy based diagnoses. Autopsy studies allow extensive tissue sampling and have highlighted intratumoral histopathologic heterogeneity. Areas within or around a grade IV astrocytoma may present with features of grade II or grade III histology that could be inadvertently targeted at biopsy.

Perhaps most importantly, DIPG histology is not a predictor of survival. Patients with low-grade histology do just as poorly as patients with high-grade histology (which is in striking contrast to the family of gliomas, where it's grade determines survival:
--- grade II - 5-7 years median survival
--- grade III - 3-4 years
--- grade IV - 15 months for glioblastomas)

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