ENT OSCE & DNB related all you ever wanted to read and download complete notes visit @www.drpulkitagarwal.com (updated everyday)

1. Fibrous Dysplasia
DEFINITION
EPIDEMIOLOGY
CLASSIFICATIONS
PRESENTATION
NATURAL HISTORY
MACROSCOPIC APPEARANCE / HISTOLOGY
DIFFERENTIAL DIAGNOSIS
TREATMENT
COMPLICATIONS
DEFINITION
Benign condition in which normal lamellar bone is replaced by fibrous connective tissue due to a
defect in osteoblast differentiation and maturation, resulting in formation of bone that is weak and
prone to expansion.
EPIDEMIOLOGY
Incidence not known
Females > Males
No race predilection
Initial symptoms manifest age 3-15yrs
Not heritable
Questionable genetic transformation
Malignant transformation in < 1%
GENETIC BASIS – GNAS1 mutation, early mutation leads to diffuse disease whereas late
mutation leads to isolated disease.
CLASSIFICATIONS
Fibrous Dysplasia can affect any bone and can be divided into four subtypes (although there is some
overlap):
1. Monostotic : single bone
2. Polyostotic : multiple bones
3. Craniofacial Fibrous Dysplasia : skull and facial bones alone
4. Cherubism : mandible and maxilla alone (not true fibrous dysplasia,
Cherubism is inherited as an Autosomal Dominant, with
Histological features indistinguishable from a giant Cell
Granuloma.
Another Classification states it into 3 types :
1. Monostotic (70 percent)

2. 2. Polyostotic (25-30 percent)
3. McCune-Albright Syndrome
MONOSTOTIC
Most common (70%)
No gender predilection
Often quiesces at puberty
25% involve head and neck
Most common sites: femur, tibia, ribs, skull
POLYOSTOTIC
25% of cases
2 or more bones
Female predilection
50% have head and neck involvement
Less likely to become inactive
McCUNE-ALBRIGHT SYNDROME
3%
Multiple bony lesions
Hyperpigmentation -- Café au lait spots
Endocrine dysfunction
– hyperthyroidism
– precocious puberty in females
It can also be classified Radiologically as –
1. Cystic (21%) – Radiolucency surrounded by solid rim
2. Sclerotic (23%) – Dense and homogenous
3. Pagetoid or Mixed (56%) – “Ground glass appearance”
PRESENTATION
Local pain (Pressure Symptom, initially no pain)
Swelling
Abnormal pigmentation
Cranial Nerve compression
Spontaneous scalp hemorrhage
Part of McCune-Albright’s syndrome
The most involved skull bones are Ethmoid (71 %) and Sphenoid (43 %). Frontal & maxillary
bones can be involved in 30 % of the cases, while temporal and occipital bones are less likely to be
affected, i.e. in 24 % and 5 %, respectively
In Head and Neck > 95 cases reported involving temporal bone leading to –
Conductive Hearing Loss (80%)
– Narrowing of the EAC.