Abstract #1

by | Sep 25, 2023 | 2023 Abstracts

Abstract 1- 1010-1025
Category: Clinical

At the end of the session, participants will be able to:

  1. Describe the morphologic spectrum of aqueductal stenosis
  2. Define mesencephalosynapsis and its association with aqueductal lesions and other CNS malformations.

COI Disclosure:

None to disclose.

Presenter

Yael Fisher, M.D., is a pathologist, trained in Rambam Medical Center in Haifa, Israel. She completed her residency in
anatomical pathology in 2019. Currently Yael is on a clinical fellowship in molecular pathology at the Pathology and Laboratory
Medicine department in Mount Sinai Hospital.

Authors

Yael Fisher1, Orli Greenberg1, Patrick Shannon1

1Pathology and Laboratory Medicine, Mount Sinai, Toronto, ON, Canada

    Target Audience:

    Pathologists, Residents, Medical Students

    CanMEDS:
    Medical Expert (the integrating role), Scholar

    Aqueductal stenosis and mesencephalosynapsis in fetal brains, part 1: classification, and morphology.

    Abstract

    Systematic studies of the histology of fetal aqueductal stenosis (AS) are uncommon. Mesecncphalosynapsis, (midline fusion of the midbrain colliculi with absence of the dorsal medial septum), is infrequently described in the literature in association with brain malformations. We conducted a 12 year review of our institutional experience with fetal obstructive hydrocephalus and AS using text word searches for aqueductal stenosis, aqueductal atresia, ventriculomegaly, hydrocephalus and rhombencephalosynapsis. We obtained 274 cases. We excluded Chiari malformations, skeletal dysplasias, ex-vacuo ventriculomegaly and cases with unsatisfactory representation of the midbrain. 118 cases of obstructive ventriculomegaly with aqueductal pathology remained. Clinical and histological features of each case were reviewed. The median gestational age was 23 weeks, interquartile range = 21 to 25 weeks. We identified 5 major morphological patterns of AS. 1) Aqueductal atresia (14 of 118, 11.9%); 2) Severe stenosis (22 of 118, 18.6%); 3) Mild stenosis (51 of 118, 43.2%); 4) Borderline stenosis (10 of 118, 8.5%); 5) Slit-like aqueduct (13 of 118, 11%). 8 cases had a seemingly patent aqueduct (6.8%), but 7 of these had a clear obstructive lesion (2 had isolated glial webbing of the aqueduct, 5 had other outflow obstructions). Mesencephalosynapsis was seen in 42 of 118 cases (35.6%), more commonly in cases of atresia and severe stenosis. Hemosiderin laden macrophages were present in the aqueduct 39 of 118 cases (33.1%). Atresia and severe AS showed a stronger association with multiple congenital anomalies and other central nervous system malformations when compared with the milder forms of AS.