A 62-year-old man has had fever and a 4-kg weight loss over the past 6 months. On physical examination, his temperature is 38.6deg C. He has generalized nontender lymphadenopathy, and the spleen tip is palpable. Laboratory studies show hemoglobin, 10.1 g/dL; hematocrit, 30.3%; platelet count, 140,000/mm3; and WBC count, 24,500/mm3 with 10% segmented neutrophils, 1% bands, 86% lymphocytes, and 3% monocytes. A cervical lymph node biopsy specimen microscopically shows a nodular pattern of small lymphoid cells. A bone marrow biopsy specimen shows infiltrates of similar small cells having surface immunoglobulins that are CD5+, but CD10-. Cytogenetic analysis indicates t (11;14) in these cells. What is the most likely diagnosis?
A 62-year-old man has had fever and a 4-kg weight loss over the past 6 months. On physical examination, his temperature is 38.6deg C. He has generalized nontender lymphadenopathy, and the spleen tip is palpable. Laboratory studies show hemoglobin, 10.1 g/dL; hematocrit, 30.3%; platelet count, 140,000/mm3; and WBC count, 24,500/mm3 with 10% segmented neutrophils, 1% bands, 86% lymphocytes, and 3% monocytes. A cervical lymph node biopsy specimen microscopically shows a nodular pattern of small lymphoid cells. A bone marrow biopsy specimen shows infiltrates of similar small cells having surface immunoglobulins that are CD5+, but CD10-. Cytogenetic analysis indicates t (11;14) in these cells. What is the most likely diagnosis?
💡 Explanation
Okay, let's tackle this question. The patient is a 62-year-old man with fever, weight loss, lymphadenopathy, and splenomegaly. His CBC shows lymphocytosis with a WBC of 24,500 and 86% lymphocytes. The lymph node biopsy shows a nodular pattern of small lymphoid cells, and the bone marrow has CD5+ CD10- cells with t(11;14).
First, I need to think about the differential diagnosis for chronic lymphocytic leukemia (CLL) and other B-cell lymphomas. The key here is the immunophenotype and the cytogenetic finding. CD5 is typically positive in CLL, which is a B-cell malignancy. The t(11;14) translocation is characteristic of mantle cell lymphoma. Mantle cell lymphoma usually presents with lymphadenopathy, splenomegaly, and has a CD5+ CD10- profile. The nodular pattern in the lymph node biopsy might also point towards mantle cell lymphoma.
CLL usually has CD5+ and CD23+, but CD10 is negative. However, CLL typically has a more indolent course and might not have the t(11;14). The translocation t(11;14) fuses the cyclin D1 gene, leading to overexpression of cyclin D1, which is a hallmark of mantle cell lymphoma.
Other possibilities like follicular lymphoma (t(14;18)) or diffuse large B-cell lymphoma (no specific translocation) don't fit here. The presence of t(11;14) is crucial here. So the correct answer is mantle cell lymphoma.
**Core Concept**
This case tests the diagnosis of B-cell lymphomas based on clinical presentation, immunophenotype, and cytogenetics. The key is recognizing the association between t(11;14)(q13;q32) and **cyclin D1 overexpression** in mantle cell lymphoma (MCL).
**Why the Correct Answer is Right**
The patient’s findings align with **mantle cell lymphoma**:
- **t(11;14)** translocation fuses the *CCND1* gene to the immunoglobulin heavy chain locus, causing cyclin D1 overexpression.
- **CD5+ CD10-** immunophenotype distinguishes MCL from other lymphomas (e.g., CLL is CD23+, follicular lymphoma is CD10+).
- Clinical features include aggressive lymphadenopathy, splenomegaly, and B symptoms (fever, weight loss).
**Why Each Wrong Option is Incorrect**
**Option A:** *Chronic lymphocytic leukemia (CLL)* presents with CD5+ CD23+ cells and t(12;21) or other chromosomal abnormalities, not t(11;14).
**Option B:** *Follicular lymphoma* is CD10+ and associated with t(14;18), not t(11;14).
**Option C:** *Diffuse large B-cell lymphoma* lacks a specific translocation and shows large cells, not small lymphoid nod
✓ Correct Answer: D. Mantle cell lymphoma
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