DISCUSSION
The diagnostic approach of a facial swelling in a child is always a
source of difficulties for the clinician. Especially for a disease with
such heterogenous clinical symptoms as BL.16 One must
be aware of pathology other than dental infection when cortical bone is
absent. BL has a predominance in males, mostly in young
patients.6,7,10,17
The panoramic radiograph (Figure 2) shows the dentition in transition
from deciduous to permanent. The second molar of each quadrant is in
development given the incomplete root formation.18 The
thin circumferential cortical layer around the second molar in the lower
jaw on the left side, which normally presents as the typical
radiological finding of the dental sac, is absent.12This aspect of this panoramic radiograph could be described as an
osteolytic zone in the lower left quadrant at the level of the angle and
ramus of the mandible. This radiolucency at dental level has already
been described in a case with leukemia by Curtis et al. presenting the
absence of the lamina dura.19 A similar dental
osteolytic presentation of oral BL has been reported by Hanazawa et al.
and Wood et al.20,21 The dental sac embryologically
relates to the periodontal ligament which closely interacts with the
lamina dura of the alveolar bone.18,22,23Radiographically BL may begin as multiple lesions, which later merge
into a larger radiolucency with an expansile behavior. The lesions are
radiolucent in almost all cases, particularly in the jaw of a
child.10
Other osteolytic pathology should be taken into account in the
differential diagnosis. Metastatic neuroblastoma, Ewing’s tumor,
rhabdomyosarcoma, osteolytic osteosarcoma and other NHL
lymphomas/leukemia must be considered.
The initial approach should involve dental imaging due to easy
accessibility and the value to exclude an odontogenic origin, one of the
most prevalent causes of facial swelling in
children.11 In case no odontogenic origin could be
found, ultrasonography should be performed, especially in case of
nodules in the neck.5 For NHL, extra nodal involvement
occurs at a frequency of 20-30% in the head and neck
region.13 In order to identify bone resorption and the
precise radiologic extent of the disease both CT and MRI are valuable
investigations. CTs have better image quality for bone imaging and a
lower cost. MRI doesn’t use ionizing radiation, has a better
characterization of bone marrow and is superior in soft tissue
contrast.5 PET-CT is useful for functional and
anatomic assessment during tumor staging and tumor response
evaluation.5
Several studies strongly suggest the involvement of the EBV in BL, since
EBV inhibits cell death and contributes to the development and
maintenance of BL.7 At the molecular level the
deregulation of the MYC proto-oncogene is a characteristic feature of
BL.24
The therapy of choice for all types of BL are short, intensive short
courses of a combination of different types of chemotherapy
(cyclophosphamide, vincristine, prednisone, doxorubicin, alkylators and
etoposide).2,6,14 The addition of immunotherapy
(rituximab) to chemotherapy is an effective therapeutic option in
high-risk, high-grade, mature BL which increases the overall survival
significantly.14 New studies are now being enrolled to
define the therapeutic-toxic margins of current therapy without further
increasing the risk of relapsing disease. Often the immune therapy is
started in the second cycle to minimize adverse
effects.2 There is no need for surgical resection nor
for radiotherapy because of the high sensitivity of BL cells to
chemotherapy and an increased rate of local complications correlated
with early surgical interventions.2,25 Surgical
excision has only a prognostic benefit when almost-complete resection
can be performed without delaying chemotherapy.26 In
this case total resection was not achieved but the hinder for the
patient’s occlusion was the incentive.
Prognostic factors are lactate dehydrogenase (LDH) concentrations, stage
of disease, leukemic bone marrow and central nervous system (CNS)
involvement together with treatment-related factors such as late or
incomplete response.14
The overall survival rate for standard risk, early/moderate stage BL
with chemotherapy alone is about 97 – 98%.14 Where
the prognosis for the more advanced, higher risk stages is
87,3%.14 A recent randomized, phase III trial found
that for these high-risk, high-stage BL the addition of six cycles of
rituximab to the standard chemotherapy resulted in an overall survival
of more than 95%.14
Follow-up is performed every two
to three months the first year following therapy through clinical
investigations, abdominal ultrasonography and blood investigations. The
frequency of follow-up decreases in the subsequent years. Most relapses
occur in the first year following therapy.14