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