Histopathology of the inner ear in patients with xeroderma pigmentosum and neurologic degeneration.
BACKGROUND
Xeroderma pigmentosum (XP) is a rare autosomal recessive disease caused by mutations resulting in defective repair of DNA damage. XP patients have a markedly increased risk of ultraviolet-induced neoplasms and premature aging of sun-exposed tissue. Approximately 25% of XP patients in the United States have neurologic abnormalities including progressive sensorineural hearing loss (SNHL).


OBJECTIVE
To describe the temporal bone histopathology in 2 individuals with XP (XPA and XPD) with neurologic degeneration and to discuss the possible causes of deafness in these patients.


METHODS
Temporal bones were removed at autopsy and studied using light microscopy.


RESULTS
In the case with XPD, the organ of Corti was missing throughout the cochlea, whereas the case with XPA demonstrated scattered presence of sensory cells in the middle and apical turns. In both cases, there was moderate-to-severe patchy atrophy of the stria vascularis in all turns, and cochlear neurons were severely atrophied compared with age-matched controls, with loss of both peripheral dendrites and central axons. There was severe degeneration of Scarpa's ganglion in the case with XPA.


CONCLUSIONS
Two cases of XP with neurologic degeneration are reported. The case with XPD demonstrated a more severe audiologic phenotype than XPA, although both had similar findings such as atrophy of the organ of Corti, stria vascularis, and spiral ganglia leading to severe or profound SNHL by the third decade of life. It is not clear if the neuronal degeneration in the inner ear was primary or secondary to loss of neuroepithelial cells.
Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts 02114, USA. lucasmvianaorl@gmail.com
Lucas M
LM
Viana
Mohammad
M
Seyyedi
Carmen C
CC
Brewer
Christopher
C
Zalewski
John J
JJ
DiGiovanna
Deborah
D
Tamura
Mariam
M
Totonchy
Kenneth H
KH
Kraemer
Joseph B
JB
Nadol
D000328:Adult; D001344:Autopsy; D003056:Cochlear Nerve / Q000473:pathology; D004247:DNA / Q000235:genetics; D018450:Disease Progression; D007758:Ear, Inner / Q000473:pathology*; D017809:Fatal Outcome; D005260:Female; D006801:Humans; D008875:Middle Aged; D009410:Nerve Degeneration / Q000150:complications / Q000235:genetics / Q000473:pathology*; D013063:Speech Discrimination Tests; D013701:Temporal Bone / Q000473:pathology; D014725:Vestibular Nerve / Q000473:pathology; D014983:Xeroderma Pigmentosum / Q000150:complications / Q000235:genetics / Q000473:pathology*
D004247:DNA