dysplasia of Maxilla
Balasubramanian M.S. D.L.O.
Fibrous dysplasia is a developmental disorder of
maxilla in which immature woven bone is formed directly
from abnormal fibrous tissue. It is characterised by an
expansile lesion of fibro osseous tissue. Fibrous dysplasia is
of two types:
1. Mono ostotic fibrous dysplasia
ostotic fibrous dysplasia
Mono ostotic fibrous dysplasia
affects a single bone commonly affecting a rib or facial
bones. It is also more common than poly ostotic fibrous
dysplasia. This condition may be associated with systemic
conditions like precocious puberty, and skin pigmentation.
This condition if associated goes under the name McCune -
Albright Syndrome. This lesion is active while the bone
is growing. The lesion becomes inactive when the growth
stops. The activity of the disease may increase later during
Poly ostotic variety affects many bones nearly 75
% of skeletal tissue may be affected. This lesion may remain
active throughout life.
Disorganised immature bone surrounded by immature fibrous
tissue is seen in the dysplastic areas. This tissue doesnot
have the capacity to mature into a lamellar bone. Hence the
normal mechanical integrity of the bone is lost affecting the weight
bearing bones in polyostotic fibrous dysplasia. Pain may be
disabling. Fractures are common. Fractured bones heal
with more immature bone tissue thereby accentuating the
dysplasia may become more aggressive and dedifferentiate causing
(desmoplastic fibroma). Sometimes the tissue may
undergo sarcomatous transformation.
Risk factors for
malignant transformation include:
1. Polyostotic form
3. Facial bone involvement
Usually fibrous dysplasia affects affects people in
their childhood / teens. Males are commonly affected than
females. Albright syndrome is an exception wherein female
preponderance is more.
molecular level, fibrous dysplasia is caused by sporadic mutation of
the GNAS1 gene that encodes the alpha subunit of the
stimulatory G protein (G1). The exact biochemical pathway that leads
to the clinical phenotype is unknown.
Involved bones consists
of immature and relatively undifferentiated fibrous connective
tissue that fails to produce normal amounts of collagen. The
collagen produced are not oriented appropriately to withstand the
Nonskeletal manifestations include
abnormal cutaneous pigmentation (jagged "coast of Maine" border),
precocious puberty, hyperthyroidism, Cushing disease,
hyperparathyroidism, and hypophosphatemic rickets. Albright syndrome
is defined as the triad of precocious puberty, polyostotic fibrous
dysplasia, and cutaneous pigmentation. Typically, only females are
affected by precocious puberty, but the other endocrine
abnormalities occur equally in males and females. All of these
abnormalities are thought to be due to the same underlying
Fibrous dysplasia of
Fibrous dysplasia of
the facial skeleton commonly involves the maxilla. It commonly
involves one maxilla. The patient manifests with unilateral
swelling of cheek (firm in consistency). Patient may have
unilateral proptosis because dysplasia involves the boundaries of
the orbit reducing the space available for the orbital
contents. Some of these patients may suffer loss of vision due
to entrapment of optic nerve in the dysplastic process.
photograph of a patient with fibrous dysplasia of left
1. Serum alkaline phosphatase levels are often
elevated depending on the extent of bony disease.
Serum calcium phosphate may also be elevated
3. Pituitary gonadotropins and gonadosteroids are
assessed to assist in the workup of precocious
Xray shows an expansile bony lesion.
Bone walls are intact. Maxillary sinus is obliterated.
CT scan shows a lesion that is confined to the interior
of the bone with no soft tissue component. It is helpful in
distinguishing fibrous dysplasia from a malignancy. Features of
malignancy include osteolysis, destruction of sclerotic margins, and
cortical destruction with soft tissue extension. The bony
lesion shows a homogenous matrix with obliteration of maxillary
scan of a patient with fibrous dysplasia of
Technetium Tc 99m methylene diphosphonate (MDP) bone
scan can be done to distinguish mono ostotic from poly ostotic
lesions. Increased uptake is more common in poly ostotic
Medical: Underlying endocrine deficiency if any must first be treated.
Vitamin D and bisphosphonates (after
physeal closure) may be helpful in ameliorating pain and possibly in
reconstituting lesions with normal
Surgical: Curettage of the
affected bone with filling up of the defect using a bone graft is
the advised surgical procedure. In the case of maxilla the
affected bone bleeds extensively when an attempt is made to curette
it. Adequate amount of blood must be reserved before
surgery. The surgical procedure is known as Parring of the
This video clipping shows Parring of maxilla being performed.
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