Wednesday, May 10, 2023

What is this?











10 year old female (4/29/13) with intractable epilepsy and profound motor and cognitive handicap. Has had extensive and unrevealing laboratory investigations. Two brain biopsies performed.  In 01/2021, she had a Stealth-guided stereotactic brain biopsy through a left frontal bur hole.  The biopsy showed white matter tracts with scattered calcifications.  The Ki-67 proliferative index was slightly elevated.  "These findings are not conclusive and we cannot rule out the possibility of neoplastic process."  She then had a repeat brain biopsy on 04/21/2021.  There were dystrophic calcifications in the subcortical white matter and extensive reactive gliosis seen involving the basal ganglia.  This was a biopsy of the left caudate.  There was no evidence of a neoplastic process.  The report indicates, "However, the findings on clinical examination and imaging studies are highly suggestive of an unusual neurocutaneous syndrome, particularly hypomelanosis of Ito." The patient does have cutaneous findings akin to those of hypomelanosis of Ito.

Any thoughts can be conveyed to


  1. One reply suggested hypomelanosis of Ito might, indeed, be the explanation. Whole exome sequencing was negative. Another reply suggested performing genetic testing on residual brain biopsy tissue. It appears that comprehensive genetic testing would likely not be possible, but that focused genetic testing for MTOR, PIK3CA, AKT3, and some others might be possible. This is being explored.

  2. Genetic testing was performed on biopsy tissue, as one colleague suggested. As another colleague predicted, there is a pathogenic MTOR mutation: p.C1483F. The VAF is 12%.