HY USMLE Q #1035 – Pathology

Summary

This educational video script discusses a pathology case of a 7-year-old boy with Burkitt lymphoma, characterized by a 'starry sky' appearance in histopathology due to tingible body macrophages engulfing apoptotic B cells. The script clarifies common misconceptions about the disease's presentation and emphasizes the importance of recognizing the 814 translocation associated with Burkitt lymphoma, contrasting it with other lymphomas and leukemias, such as follicular lymphoma and APL. It concludes with a call to action for viewers to support more content creation.

Takeaways

• 🔬 The pathology image described is indicative of Burkitt lymphoma, characterized by a 'starry sky' appearance due to the presence of basophilic background of B cells and pale, larger cells which are tingible body macrophages.
• 📚 Tingible body macrophages are known to engulf apoptotic B cells, which is an important histological feature to recognize in Burkitt lymphoma.
• 🧬 The t(8;14) translocation is associated with Burkitt lymphoma, involving the c-Myc gene, a transcription factor, and is a key genetic abnormality to know for exams.
• ❌ The script clarifies that t(14;18) translocation is incorrect for Burkitt lymphoma; instead, it is associated with follicular lymphoma and involves an anti-apoptotic molecule, BCL2.
• 📈 Follicular lymphoma often presents as a waxing and waning painless neck mass and is the most common indolent (slow-growing) non-Hodgkin lymphoma.
• 🧬 The t(15;17) translocation is associated with acute promyelocytic leukemia (APL), also known as AML type M3, and involves the PML-RARA gene fusion.
• 💊 All-trans retinoic acid is a treatment for APL, highlighting the importance of knowing therapeutic options for specific genetic abnormalities in leukemia.
• 🧬 The Philadelphia chromosome, or t(9;22) translocation, results in the BCR-ABL fusion protein and is associated with chronic myeloid leukemia (CML), a high-yield topic for medical exams.
• 📝 The script emphasizes the importance of understanding the genetic abnormalities and their clinical correlations for various types of lymphoma and leukemia, which are crucial for medical examinations.

Q & A

What is the most likely diagnosis for a 7-year-old boy with a one-month history of generalized Abdus, fatigue, and a 2 cm mass left of the umbilicus?

The most likely diagnosis, based on the description and biopsy findings, is Burkitt lymphoma, which is characterized by a starry sky appearance with basophilic background of Burkitt B cells and tingible body macrophages.

What does the term 'starry sky' appearance refer to in the context of Burkitt lymphoma?

The 'starry sky' appearance refers to the characteristic histological feature of Burkitt lymphoma where pale-staining macrophages are scattered among darker staining lymphoma cells, resembling stars in the sky.

What is the significance of tingible body macrophages in Burkitt lymphoma?

Tingible body macrophages are significant because they indicate the presence of apoptosis within the tumor. These macrophages engulf and digest apoptotic Burkitt B cells, contributing to the 'starry sky' appearance.

What is the role of apoptosis in Burkitt lymphoma despite it being a hyper-proliferating cancer?

Even though Burkitt lymphoma is a rapidly proliferating cancer, there is still cell turnover occurring, leading to apoptosis. This process is highlighted by the presence of tingible body macrophages that phagocytose apoptotic B cells.

What is the significance of the 814 translocation in Burkitt lymphoma?

The 814 translocation is significant as it is almost always associated with Burkitt lymphoma and involves the c-Myc gene, a transcription factor that plays a role in the pathogenesis of the disease.

How does the presentation of Burkitt lymphoma differ from that of follicular lymphoma?

Burkitt lymphoma often presents with abdominal masses, while follicular lymphoma typically presents as a waxing and waning painless neck mass over one to two years. Follicular lymphoma is also associated with a 14;18 translocation involving the BCL2 gene.

What is the treatment implication of the 15;17 translocation in acute promyelocytic leukemia (APL)?

The 15;17 translocation in APL results in the fusion of the PML and RARA genes, leading to the production of a PML-RARA fusion protein. All-trans retinoic acid can be used as a treatment to differentiate the leukemic cells.

What is the Philadelphia chromosome associated with, and what is its clinical significance?

The Philadelphia chromosome is associated with a 9;22 translocation, leading to the fusion of the BCR and ABL genes. This fusion protein, BCR-ABL, is a constitutively active tyrosine kinase, driving the pathogenesis of chronic myeloid leukemia (CML).

Why is it important to know the difference between the translocations associated with Burkitt lymphoma and follicular lymphoma?

Knowing the difference between the translocations for Burkitt lymphoma (8;14) and follicular lymphoma (14;18) is important for accurate diagnosis and treatment planning, as they involve different genes and have distinct clinical presentations and outcomes.

What is the significance of the term 'indolent' when describing non-Hodgkin lymphomas?

The term 'indolent' refers to a slow-growing, less aggressive form of non-Hodgkin lymphoma, such as follicular lymphoma. These types of lymphomas often have a more chronic course and may require different treatment approaches compared to more aggressive forms.