DISCUSSION
Lymphoid neoplasm encompasses group of white cell neoplasm varying in clinical presentation and behavior; Leukemias arising in bone marrow and circulating peripheral blood, lymphomas appearing as tumour masses from lymph nodes or other organs and plasma cell dyscrasias composed predominantly of plasma cells. Sometimes, distinction between these clinical categories of lymphoid neoplasia is difficult.6
Lymphomas are divided into two major group; Hodgkin and Non-Hodgkin lymphoma. The non-Hodgkin lymphomas are further sub-divided into B-cell and T-cell lymphomas. Burkitt’s Lymphoma belongs to peripheral B cell neoplasm.7 There are 3 different types of BL: endemic (African) form, the sporadic (non-African) form and immunodeficiency-linked variety. The endemic form, which is the most prevalent worldwide; affects younger children (4 to 7 years) involving the head and neck (maxilla and mandible involvement in 58%). Concomitant (endemic) malaria (or other infections) impairs immune competence; allowing sustained B cell proliferation commonly seen in this variant.8 Symptoms include cervical lymphadenopathy, swelling of the jaw or facial mass, proptosis, teeth mobility, paresthesia, and pain.9 Sporadic Burkitt’s lymphoma (usually seen in European populations) shows gastrointestinal involvement (56% of the cases) and is found more often in older children(male> female). Both endemic and Sporadic Burkitt’s lymphoma rarely arises in the lymph nodes. Immunodeficiency associated Burkitt lymphoma is frequently seen in AIDS patients and patients on immunosuppressive drugs following organ transplantation and can be found in extra-nodal sites; abdomen being common site. Abdominal pain, vomiting, bowel obstruction and gastrointestinal bleeding constitutes the usual clinical presentation.10
Manifestations of BL are variable depending on the site of involvement and the extension toward the adjacent structures. Sometimes, systemic symptoms such as fever, weight loss, and headache might be seen.11 Rapid progression of symptoms can be seen that can even reach 24 to 48 hours. 9 Our patient mainly presented with sore throat and foreign body sensation in the throat that was attributed to the oropharyngeal extension. In fact, symptoms in oropharyngeal BL are not specific to this entity and can delay the diagnosis, since BL mainly manifests with cervical lymphadenopathy. Physical examination findings can also be misleading as oropharyngeal BL typically presents as a polypoid mass resembling other tumorous condition.9
Although the diagnosis of BL is confirmed pathologically, multimodality imaging approach imaging plays a critical role throughout the clinical course from diagnosis to follow up imaging.12According to the National Comprehensive Cancer Network (NCCN) guidelines, initial staging should be performed with cervical and abdominal ultrasound, CT of the chest, abdomen, and pelvis. Depending on the clinical presentation, contrast-enhanced neck and/or brain MRI may also be done.12 CT scan is a crucial to assess tumor localization, staging of the disease and post-treatment monitoring. Currently, Gadolinium enhanced MRI is also the best imaging modality for confirming oropharyngeal location, extension, its relationship to the adjacent structures, and follow-up of BL. Compared with CT, MR imaging can demonstrate homogenously enhancing mass with isointense signal on T1-weighted images and an iso or hyper-intense signal on T2-weighted images due to the cellularity and tends to infiltrate surrounding structures without their destruction, especially in sporadic forms. In contrast, endemic variants are characterized by osteolytic bone lesion with destruction of maxilla-facial bones with an enlargement and invasion of the adjacent structures.13 Our patient also presented as an infiltrating homogenous mass with a hypo-intense signal on T2-weighted images. However, CT and MRI findings are not specific to this entity, and their findings can mimic other aggressive diseases of the oropharynx.
Role of diffusion weighted imaging (DWI) and ADC value in BL is still under study. Positron emission tomography (PET), when combined with CT, offers the advantage of combining functional information with anatomic imaging.14An increasing amount of research is being done to assess the value of PET/CT in patients with BL and should be performed if possible, provided it will not delay treatment.12
Biopsy, immunohistochemistry and genetic analysis are other tests helpful to get correct diagnosis. All variants of Burkitt lymphoma share the same morphology and it is almost impossible to differentiate these three variants on microscopic features alone. They are strongly associated with translocations involving the MYC oncogene on chromosome 8. Histopathology, BL typically has characteristic starry-sky pattern. However, immunohistochemistry is a useful method for identifying particular tumor cells that includes expression of CD20, CD10, and bcl-6, Ki-67 proliferation rate.15
Bone marrow, Cerebrospinal fluid, Lactate Dehydrogenase Level, HIV and Epstein-Barr Virus serology may also be required.16EBV exhibits strong tropism for B cells and infects them, causing them to proliferate. In our case, the patient had positive antibodies for Epstein–Barr virus. Virtually all cases of endemic BL carry EBV genome whereas < 30% of sporadic and immunosuppression‑associated variant are associated with this EBV virus. 17
The definitive treatment of BL is often based on the patient’s age and the location of tumor. Different modalities such as surgery, radiotherapy, chemotherapy, and radioimmunotherapy have been used to treat Burkitt’s lymphoma, but systemic chemotherapy is mainstay of treatment. BL dramatically responds to chemotherapies that includes cyclophosphamide, vincristine, methotrexate, and prednisone causing regressions of tumor and often lead to long-term remission.18 Our patient was also placed under complex chemotherapy resulting in the regression of the mass confirmed on post-therapeutic imaging.
The role of surgery in BL is still controversial. Surgical treatment is generally not required unless disease complications require prompt surgical intervention such as in cases of bowel obstruction, optic nerve decompression and airway obstruction.19
Prognosis depends on the stage of the disease at presentation, age of patient, chemotherapy, lactate dehydrogenase levels and the association with HIV. Patients who receive an early treatment are associated with better outcomes in comparison to the delayed treatment which can cause BL to reach other distant organs.20 Patients with relapsed disease usually present symptomatically and within the first year after the completion of treatment. Relapsed disease may occur at the sites of original presentation or remotely. 12