Transcription
Burkitt's lymphoma, the most rapidly progressive human tumor ever, it really breaks my heart. I hope in the future we can treat these kids better, because Burkitt's lymphoma is a terrible cancer. [Music]
As you know from previous videos, lymphoma is Hodgkin's and non-Hodgkin's. Non-Hodgkin's is more common. Non-Hodgkin's is nodal and extranodal, such as any organ, which will lead to symptoms triggering a diagnosis. Non-Hodgkin's could be B-cell or T-cell. B-cell could be aggressive or indolent. Aggressive, such as Burkitt's. However, Burkitt's is not the most common aggressive type; diffuse large B-cell lymphoma is. The previous classification was not very accurate because it only takes into account that morphological structure, such as the Reed-Sternberg result. It's only an appearance. However, the World Health Organization takes into account morphological, clinical, genetic, and immunological information, and it breaks them down into B-cell lymphomas, T-cell lymphomas, and Hodgkin's lymphoma.
Since Burkitt's lymphoma is a non-Hodgkin's lymphoma, it will have nodal involvement. Extranodal involvement can be any organ, plus constitutional symptoms such as fever, weight loss, and night sweats, associated with Epstein-Barr virus as well as HIV. Abnormal labs in non-Hodgkin's lymphoma: pancytopenia, hyperuricemia, hypercalcemia, increased LDH, and M spikes on serum protein electrophoresis. Hyperuricemia is part of the tumor lysis syndrome, which has high potassium, high phosphate, high uric acid, but low calcium. Why is that? Because phosphate precipitates calcium by binding with it, leaving less free calcium in the plasma.
Non-Hodgkin's lymphoma again: aggressive or indolent. Aggressive, such as Burkitt's. Patients are younger, more B symptoms, sensitive to chemo. Median survival rate, unfortunately, is very short. And here is the aggressive versus indolent non-Hodgkin's lymphoma. Burkitt's lymphoma is here. Okay. Burkitt's lymphoma usually affects young males. In fact, 30% of children with non-Hodgkin's lymphoma have Burkitt's. So Burkitt's lymphoma is commoner in children than in adults, and it's one of the AIDS-defining malignancies. Also, AIDS-defining malignancies include Kaposi sarcoma, primary CNS lymphoma, and cervical carcinoma. And by the way, Kaposi sarcoma is the most common malignancy in AIDS patients. It's common in sub-Saharan Africa, associated with Epstein-Barr virus and HIV. Because it's a non-Hodgkin's, it will have extranodal involvement, such as the bone marrow, leading to a leukemic phase, or malignant cells in the blood, and we call this Burkitt's leukemia.
Burkitt's lymphoma has an American subtype and African subtype. American subtype usually involves the GI tract, para-aortic, and pre-aortic lymph nodes. African type usually involves the jaw and is commonly associated with Epstein-Barr virus. Burkitt's lymphoma again, the most rapidly progressing human tumor ever, which is so bad. We have three types of Burkitt's lymphoma: endemic, also known as African; sporadic, also known as American; plus immunodeficiency-associated. The endemic type is common in sub-Saharan Africa. As you know, Africa can be divided into North Africa and sub-Saharan Africa. The endemic type involves the jaw. Here is a beautiful mandible for you. Sporadic, or American type, usually has abdominal GI symptoms, such as abdominal distension, also pre-aortic and para-aortic lymph adenopathy. Immunodeficiency, in people with decreased immunity, such as patients with HIV.
Now the pathophysiology is just great. We have two chromosomes: chromosome 8 and chromosome 14. Here we have MYC, it's a proto-oncogene. What does that mean? Gene that will cause genesis to oncology; it will produce cancer. Proto means it's primary, it's primitive; it will lead to cancer. It's proto-oncogene. And on chromosome 14, we have IgH, which is the heavy chain of the immunoglobulin. We have two breaking points here, and now we will get a reciprocal translocation. MYC will go from 8 to 14, and the IG will go from 14 to 8. This is called reciprocal translocation. Burkitt's lymphoma is here, with MYC on 14 and the heavy chain of IG is on 8. Now MYC is very close to IG gene, which will act as a promoter, leading to MYC amplification. Amplification of MYC equals increased cell division. And here's a beautiful amplifier for you. MYC amplification is also known as enhancer activation or transcriptional activation; same stuff.
Clinically: rapid focal tooth loosening. Although the most common cause of rapid focal tooth loosening is infection, also Burkitt's lymphoma, especially the African subtype, can lead to this problem. Lymph adenopathy plus intra-abdominal mass, and pre-aortic lymph adenopathy is common in the American subtype. Sorry, I've switched them. Lymph adenopathy + jaw mass is the African subtype. It can metastasize, of course, to the CNS, because it's a non-Hodgkin's lymphoma with extranodal involvement. Staging by physical exam and the CT scan. When you do an excisional biopsy of the lymph node and put the slide under the microscope, you will find a starry sky appearance, because pathologists are romantic people. What is the star and what is the sky? The sky is the background of neoplastic B-cells; these are the malignant B lymphocytes. The stars are the reactive histiocytes or macrophages. Why are they here? Because they are trying to clear the dead cells. So the macrophage is the star; the malignant B-cells are the background. You have a starry sky appearance; what a name!
In the next videos, we'll discuss diagnosis and treatment options of Burkitt's lymphoma. Then we'll have a mnemonic; then we'll have a case. Thank you so much for watching. This is Medicals Perfection Alice. Be safe, stay happy, and study hard.