Osteogenesis Imperfecta Type V - Osteogenesis Imperfecta - page 175

FIGURE 20.7 Abnormal ossification other than hyperplastic callus or radioulnar interosseous membrane ossification. Subperiosteal bone for-
mation (A) at the distal radius of a 15-year-old boy; (B) at the calcaneus of a 9-year-old boy and (C, D) at the posterior aspect of the distal humerus
of a 4.5-year-old girl. The sagittal two-dimensional reconstruction image shows layers of newly formed bone. (E, F, G) Heterotopic ossification
around both hips resulting in complete ankylosis of the hip joints in a 50-year-old man.

others just experience brief episodes of tenderness. In the
chronic phase, only radiographic signs remain without
any clinical symptoms in some patients or chronic pain
may persist in others. We observed more extensive ossi-
fication in middle-aged or older patients, which propa-
gated along the intermuscular septa of the limb segments
as well as the hip joint capsule and the fasciae of the pel-
vic girdle muscles, resulting in complete bony ankylosis
of the hip joint ( Figure 20.7E, F and G ).

FIGURE 20.8 Metaphyseal radiodense bands at the distal radius
(A), distal femur and proximal tibia (B).

Metaphyseal Radiodense Band (MRB)
MRB is a white band at the metaphysis immediately
adjacent to the physis visualized on a plain radiograph,
and is considered as one of the conspicuous radiographic
signs of OI type V in growing children ( Figure 20.8 ). 1 It
is well contrasted with osteopenia at the rest of the long
bone segment. It tends to attenuate with age. 29
No histologic data for this radiographic finding is
available, and its pathogenic mechanism is not elu-
cidated. This sign should be differentiated from the
metaphyseal sclerotic band(s) formed after bisphospho-
nate treatment, which reflects the persistent primary
spongiosa due to suppressed osteoclastic resorption. 40,41

sides as showing acute angulation medially close to the
costovertebral junction. 43 Kim et al. counted a pyra-
midal-shaped chest as one of the characteristic radio-
graphic signs of OI type V, and reported a distinctly
abnormal course of ribs in 14 of 16 mutation-confirmed
OI type V patients. 29

HISTOPATHOLOGIC AND LABORATORY
FINDINGS

Characteristic histopathologic finding is considered
as one of the diagnostic criteria of OI type V. 1 Polarized
light microscope shows well-organized, smooth lamel-
lae at the haversian system of the cortical bone and tra-
becular bone from normal subjects. In all the OI type V
patients undergoing bone biopsy, an irregular pattern of
the lamellar arrangement and a coarsened or mesh-like
appearance were observed ( Figure 20.10 ). 1,30,33 It is well

Chest Wall Deformity
Chest wall deformity has been mentioned by some
authors, but did not draw much attention compared
with forearm and elbow deformities ( Figure 20.9 ).
Arundel et al. described it as a bell-shaped chest wall, 42
and Fleming et al. described the upper five ribs on both