A nine-year-old girl presented with a slowly growing swelling of approximately
two centimeters diameter, just above the left supra orbital ridge for about
two months.(fig.1) There was no history of trauma or pain or fever. On examination,
the swelling was firm and non-tender. The overlying skin was normal There was
another small swelling in the submandibular region on the left side.
Fig.1
Her hemoglobin was 10.4gm %, and there was lymphocytosis. The ESR was 20mm at
the end of the first hour. The frontal radiograph of the chest was normal. Plain
radiographs of the skull (fig 2) and ultrasonography (fig 3,4) of the lesions
were done.
Fig.2
Fig.3
Fig.4
The frontal radiograph of the skull shows irregularity of the superior border
of the left orbit. Ultrasonography of the swelling shows an approximately three
cms by two cms, hypoechoic, well defined mass situated in the supero-lateral
aspect of the orbit causing erosion of underlying bones. Sonography of the submandibular
region revealed a non-necrotic submandibular lymphnode.
Plain and contrast enhanced CT scans of the orbit were then done for better
evaluation of the lesion (Fig 5,6,7,8).
Fig.5
Fig.6
Fig.7
Fig.8
There is a 2.5 cms by 1.7 cms sized, well defined hypodense lesion in the pre-septal
space and in the lacrimal fossa with central hypodensity suggestive of necrotic
changes which on contrast injection show peripheral enhancement extending into
the temporal fossa. There is underlying destruction of the roof of the left
orbit with no sclerosis or periosteal reaction. Associated inflammatory changes
are noted in the lateral rectus muscle. The globe and retro-orbital structures
are normal.
In view of the destructive lesion and soft tissue swelling, a possibility of
neoplastic etiology was considered. Fine needle aspiration and cytology of the
submandibular gland and the swelling was performed to confirm a diagnosis. Cytology
showed typical caseating discrete and confluent tubercles with Langerhan's giant
cells.
DISCUSSION:
Tuberculosis (TB) is rampant and endemic in developing countries, it can manifest
as pulmonary and extra -pulmonary TB with incidence of skeletal manifestation
being only 1-2%. Bones involved are the spine (dorso-lumbar) followed by the
skull, shoulder girdle and hip bones - the orbit being only rarely involved.
In skeletal TB, multifocal involvement is well known with unifocal being rarer.
Atypical site and unusual manifestations are seen specifically in the pediatric
age group. The characteristics of lesions and amount of destruction depend upon
host immunity , prior sensitization and the infectivity of the organisms.
Skeletal TB commonly give rise to a lytic,destructive lesion, sometimes associated
with button sequestrum characteristicaly seen in skull. In the pediatric age
group, such as in our case, with such an osteolytic lesion and overlying soft
tissue swelling, the possibility of following differentials is to be considered
-
Osteomyelitis, dermoid and epidermoid, eosinophilic granuloma, neuroblstoma,
lymphangioma, Ewings sarcoma.
Osteomyelitis (pyogenic): It is common in the 2-12year age group with a
male: female ratio being 3:1 - often, associated with preexisting respiratory
or genitourinary infection. The lesions characteristically show moth-eaten or
permeative medullary and cortical destruction and new bone formation.
Dermoid and epidermoid: A teratoma occurs more commonly in the midline and
at the line of fusion of all three layers i.e endoderm , mesoderm and ectoderm.
It is common in children and causes scalloping of the underlying bone.
Eosinophilic granuloma: This is often seen under the age of five tears.
Multifocal, sharply defined osteolytic lesions - a majority involving the skull
and the mandible-shows a characteristic "hole within hole" appearance due to
the involvement of the inner and outer tables. A button sequestrum may also
be present.
Ewing's sarcoma : Common between the age of 5-15 years , average being 15
years with male:female ratio of 2:1, Majority affects long bones, is diaphyseal
in location and associated with marked soft tissue involvement. Ewing sarcoma
has a typical "onion peel" appearance with laminated periosteal changes. On
CT scan, it appears as an isodense mass surrounded by a hypodense area and hyperostosis.
It is also enhances with contrast.
Neuroblastoma: Common entity in children less than five years of age . Boys
are affected more often than girls. A majority of these lesions shows a permeative
appearance and characteristic osteolytic lesions with soft tissue involvement,
which on contrast enhancement, shows peripheral enhancement. Skull involvement
is generally associated with intracranial metastasis.
Specific characteristic findings noted on plain radiographs, ultrasound and
CT help us to reach a specific diagnosis in a given unusual case. With the aid
of different imaging modalities, a diagnosis can be made with greater accuracy.
Plain Radiography:
Shows bone destruction, erosion , sclerosis and soft tissue swelling.
Ultrasound:
Characteristic cystic and solid lesions and delineates bony erosions and calcifications.
Enlarged lymph nodes can also be seen easily. Doppler examination reveals a
significant increase in the vascularity caused by any inflammation. Abscesses
caused by TB infection are seen as hypoechoic areas on ultrasound and can be
differentiated from tumors. For biopsy or aspiration cytology, ultrasound can
be used to monitor the needle and then follow up the response.
CT and MRI:
CT can accurately diagnose bony destruction and the extent of the lesion in
tumorsas well as infection. MRI is more suited to looking at the soft-tissue
extension than bone erosions or calcifications.
In endemic areas, especially in the pediatric age group, bone tuberculosis is
an important differential for multifocal osteolytic areas with overlying soft
tissue swelling - irrespective of the location of the lesions.
