Welcome to USMLE practice question #150! Today’s topic is Oncology.
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A 64-year-old man presents with a 3-month history of unintentional weight loss, night sweats, and intermittent fever. He reports generalized fatigue and painless swelling in his neck. Physical examination reveals several enlarged, nontender lymph nodes in the cervical and supraclavicular regions. A lymph node biopsy is performed, and histopathological examination shows the following findings: Sheets of monotonous, medium-sized lymphoid cells and a high mitotic index with numerous apoptotic bodies. Immunohistochemical staining reveals CD10 positivity and BCL6 expression. Which of the following is the most likely diagnosis?
A) Burkitt lymphoma
B) Diffuse large B-cell lymphoma
C) Follicular lymphoma
D) Mantle cell lymphoma
E) Small lymphocytic lymphoma
Detailed Breakdown of Answers + Correct Answer Below ⏬
GENERAL ANALYSIS
A 64-year-old man presents with systemic "B symptoms" (weight loss, night sweats, fever), painless lymphadenopathy, and lymph node biopsy findings of sheets of monotonous, medium-sized lymphoid cells, a high mitotic index, and numerous apoptotic bodies.
ANSWER CHOICES:
CHOICE A: Burkitt lymphoma
Explanation: Burkitt lymphoma is a highly aggressive B-cell lymphoma characterized by:
• Sheets of monotonous, medium-sized lymphoid cells.
• A high mitotic index and numerous apoptotic bodies.
• A "starry sky" appearance on histology due to macrophages clearing apoptotic debris.
• Immunophenotype: CD10+, BCL6+, and MYC translocation (t(8;14)).
The histological findings (high mitotic index, apoptotic bodies) and immunohistochemical markers (CD10+, BCL6+) strongly suggest this diagnosis.
CHOICE B: Diffuse large B-cell lymphoma
Explanation: DLBCL is the most common type of non-Hodgkin lymphoma in adults. It is characterized by large lymphoid cells with diffuse growth patterns. Immunophenotype can include CD10+ or BCL6+, but the mitotic index is typically lower than in Burkitt lymphoma. While DLBCL can express CD10 and BCL6, the high mitotic index and numerous apoptotic bodies are more characteristic of Burkitt lymphoma.
CHOICE C: Follicular lymphoma
Explanation: Follicular lymphoma is an indolent B-cell lymphoma characterized by nodular or follicular growth patterns. It often involves t(14;18), leading to overexpression of BCL2. Immunophenotype includes CD10+ and BCL2+. Follicular lymphoma has a low mitotic index and lacks the aggressive features (e.g., high mitotic rate, apoptotic bodies) seen in this patient.
CHOICE D: Mantle cell lymphoma
Explanation: Mantle cell lymphoma is an aggressive B-cell lymphoma characterized by small to medium-sized lymphoid cells. It is associated with t(11;14), leading to overexpression of cyclin D1. Immunophenotype includes CD5+ and cyclin D1+. This patient’s biopsy does not show cyclin D1 expression or CD5 positivity, ruling out mantle cell lymphoma.
CHOICE E: Small lymphocytic lymphoma
Explanation: SLL is an indolent B-cell malignancy that is closely related to chronic lymphocytic leukemia (CLL). It typically shows small, mature lymphocytes with a low mitotic index. Immunophenotype includes CD5+ and CD23+. The high mitotic index and medium-sized lymphoid cells in this patient’s biopsy are inconsistent with SLL.
FINAL VERDICT…
CORRECT ANSWER: A) Burkitt lymphoma
This 64-year-old man presents with systemic "B symptoms" (weight loss, night sweats, fever), painless lymphadenopathy, and lymph node biopsy findings of sheets of monotonous, medium-sized lymphoid cells, a high mitotic index, and numerous apoptotic bodies. Immunohistochemical staining shows CD10 positivity and BCL6 expression, which are consistent with Burkitt lymphoma, a highly aggressive B-cell non-Hodgkin lymphoma.
KEY CONCEPTS:
Burkitt Lymphoma Features:
Aggressive B-cell non-Hodgkin lymphoma.
Histology:
Monotonous, medium-sized lymphoid cells.
High mitotic index.
Numerous apoptotic bodies ("starry sky" appearance due to macrophages).
Immunophenotype:
CD10+, BCL6+.
MYC translocation (t(8;14)) leading to MYC overexpression.
Differentiating Lymphomas by Key Features:
Clinical Presentation of Burkitt Lymphoma:
Rapidly enlarging lymphadenopathy.
Systemic "B symptoms" (fever, weight loss, night sweats).
Commonly involves extranodal sites (e.g., abdomen, CNS).
Management of Burkitt Lymphoma:
Requires urgent treatment due to rapid progression.
Intensive chemotherapy regimens.