All are markers of Mantle cell lymphoma except
**Core Concept**
Mantle cell lymphoma (MCL) is a rare type of B-cell non-Hodgkin lymphoma characterized by the overexpression of cyclin D1 due to the translocation t(11;14)(q13;q32), leading to uncontrolled cell proliferation. The diagnosis of MCL relies on a combination of clinical, morphological, and immunophenotypic features.
**Why the Correct Answer is Right**
Mantle cell lymphoma is typically associated with the overexpression of cyclin D1, which can be detected using immunohistochemistry. The diagnosis of MCL also relies on the presence of SOX11 positivity, a transcription factor that is often expressed in MCL. In addition, MCL often exhibits a specific immunophenotypic profile, including the expression of CD5 and CD20, and the absence of CD23.
**Why Each Wrong Option is Incorrect**
**Option A:** While CD5 is often expressed in MCL, it is not a specific marker for this disease. CD5 is also expressed in other types of lymphoma, such as chronic lymphocytic leukemia (CLL).
**Option B:** SOX11 is a specific marker for MCL, and its expression is often used to distinguish MCL from other types of lymphoma.
**Option C:** CD20 is a pan-B-cell marker that is expressed in many types of B-cell lymphoma, including MCL.
**Option D:** CD23 is typically absent in MCL, and its presence can help to distinguish MCL from CLL.
**Clinical Pearl / High-Yield Fact**
Mantle cell lymphoma often presents with a distinctive morphological appearance, including a "clockface" or "sleeve" pattern of infiltration, which can be helpful in making the diagnosis.
**Correct Answer: A. CD5 is not a specific marker for MCL.**