H. Kitoh et al., EXTRA PELVIC OSSIFICATION CENTERS IN THANATOPHORIC DYSPLASIA AND PLATYSPONDYLIC LETHAL SKELETAL DYSPLASIA-SAN DIEGO TYPE, Pediatric radiology, 28(10), 1998, pp. 759-763
Citations number
23
Categorie Soggetti
Radiology,Nuclear Medicine & Medical Imaging",Pediatrics
The platyspondylic lethal skeletal dysplasias (PLSD) are a group of he
terogeneous disorders including thanatophoric dysplasia (TD) and the T
D variants (San Diego, Torrance, and Luton types). TD is the most comm
on form and has been divided into two subtypes (TD1 and TD2) based on
clinical and radiologic criteria and analysis of mutations in the fibr
oblast growth factor receptor 3 (FGFR3) gene. The variants are disting
uished from TD by characteristic radiographic and chondro-osseous morp
hologic features. We, have recently identified FGFR3 mutations in PLSD
-San Diego type (PLSD-SD) which are identical to those found in TD1, b
ut the known TD FGFR3 mutations were not found in the other PLSD varia
nts. After reviewing radiographs from 32 cases of PLSD-SD and 47 cases
of TD with gestational ages under 24 weeks, we noted novel accessory
ossification centers in the ischia of 18 cases of PLSD-SD and 44 of TD
, and the ilia in 18 cases of PLSD-SD and 20 of TD. Only three cases o
f TD and five cases of PLSD-SD did not have extra pelvic ossification
centers. At a gestational age greater than 24 weeks, the extra centers
are fused with the main bone. The radiographic appearance and chondro
-osseous morphology of cases with and without accessory pelvic ossific
ation centers were otherwise indistinguishable. Morphologically, the a
ccessory pelvic ossification centers resulted from membranous ossifica
tion. Extra pelvic ossifications are a common radiographic finding in
TD and PLSD-SD.