Fibrous
cortical defect
Non-Ossifying Fibroma
Nonosteogenic fibroma
Fibroxanthoma,
xanthogranuloma of bone
Campanacci's syndrome
Fibrous cortical defect, a benign fibroblastic
mass, also termed benign cortical defect and nonossifying fibroma.
The lesion typically arises in the metaphyses of long bones
particularly the distal femur and tibia. It is common, possibly
affecting more than 40% of boys and 30% of girls with an age range
215 years. The lesion is thought to originate at the insertion site
of a ligament or tendon and it has been suggested that it may
reflect a previous traction injury. Although the lesion arises in
the metaphyseal region it may migrate towards the diaphysis with
growth. The lesions are usually asymptomatic, although they are
occasionally associated with pathological fractures.
Radiography
show an eccentric lucent lesion with thinned cortex,
which may have a multilocular appearance and often a sclerotic
margin (Fig.1). The lesions spontaneously regress with time;
radiographs will show increasing marginal sclerosis followed by
progressive ossification of the lesion extending from its diaphyseal
aspect. The appearance on conventional radiographs should be
characteristic and no further imaging is indicated.
  
Aggressive malignancies tend to have less well defined borders, and
more periosteal reactions, resulting in a large, less sharply
defined transition zone between the lesion and normal bone
However, the lesions are commonly seen as incidental findings on
other imaging. Scintigraphy may show increased activity depending on
the stage of healing. Likewise MR imaging may show variable signal
intensity depending the lesion's stage of healing. There is often
central decreased T2-weighted signal due to collagen and
haeomosiderin deposition.
Lesions persisting in older children which are more than 2 cm in
size have been termed nonossifying fibromas but appear to represent
the same histological entity. They often extend into the medullary
cavity and are associated with an increased risk of pathological
fracture due to their size. Also, see Campanaccis syndrome.
CT scan
CT scan should not be performed unless a strong doubt
about diagnosis is present, except to confirm a pathological
fracture (see Image). This lesion is located eccentrically and CT
scan should depict a central lucency. CT scan may confirm a
minimally displaced fracture.
This scan could help in preoperative planning in FCDs in rare
locations like femoral neck.
Bone scan
This study is not indicated for diagnosis. Nevertheless,
in some cases, a methylene diphosphonate (MDP) technetium bone scan
could help to appreciate biological activity of lesion.
A minimal increased uptake can be seen as depicted in rni image. In
associated fractures, this study is not useful.
Treatment
is usually unnecessary because healing occurs
spontaneously over a period of several years. If a pathological
fracture occurs across an exceptionally large lesion then curettage
and bone grafting is required.
This kind of tumor is neither malignant, nor aggressive, so the
primary reason to treat it is to avoid a fracture, especially in
athletic children. In some cases, a non-ossifying fibroma may
require no treatment at all, because this condition resolves on its
own over time. However, your child's orthopaedic surgeon may decide
that an operation is warranted if a fracture has occurred or the
tumor is weakening the bone, putting it at significant risk of a
fracture. This may be a very difficult decision for the parents and
the surgeon. The risks of surgery and the healing and rehabilitation
time must be balanced against the desire to play sports and avoid
fracture. There is no right or wrong answer and the decision needs
to be individualized to the child.
If an operation is recommended, the procedure of choice
is usually curettage and bone grafting. Curettage is an operation
during which the tumor is scraped out of the bone with a special
instrument called a curette that has a scoop, loop or ring at its
tip. For this procedure, surgeons make an incision in the bone to
create a window. The tumor is completely curetted and the remaining
cavity is then packed with donor bone tissue (allograft), bone chips
taken from another bone (autograft), or other materials depending on
the preference of the surgeon. The patient is usually placed in a
cast or brace for six weeks and then can undergo protected weight
bearing for another six weeks. It usually takes 3-6 months before a
child can return to contact sports.
If a fracture is involved, the operation is put off until the
fracture heals with cast immobilization followed by a period
observation after it has healed. In major long bones, such as the
femur, internal fixation (surgically placed metal rods and pins to
fix a broken bone) may be necessary. At times, during the healing
process, the tumor may heal as well.
Prognosis
Although every patient is different, the long-term
outlook for a patient with a non-ossifying fibroma is generally
excellent. These tumors, as a rule, resolve on their own, usually at
skeletal maturity. The concern lies in whether they will cause a
fracture while active. Recurrence is rare.
Jaffe-Campanacci syndrome (Mario Campanacci, 20th
century, Italian physician) is a constellation of symptoms including
multiple non-ossifying fibromas, cafe-au-lait spots, mental
retardation, hypogonadism, ocular and cardiovascular abnormalities.
Campanacci's syndrome,
Radiologically there are multiple, non-ossifying fibroma found
dominantly in the long bones, pelvis and mandible. There may be
kyphoscoliosis.
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