Which is the most common lymphoma in adults?
**Core Concept**
Diffuse large B-cell lymphoma (DLBCL) is a type of non-Hodgkin lymphoma characterized by the rapid growth of large, abnormal B lymphocytes. It is the most common subtype of non-Hodgkin lymphoma in adults and can arise in any lymphoid tissue, including lymph nodes, spleen, and bone marrow.
**Why the Correct Answer is Right**
DLBCL arises from germinal center B cells, which have undergone malignant transformation. The pathogenesis involves the activation of various signaling pathways, including the nuclear factor kappa B (NF-ΞΊB) pathway, which promotes cell proliferation and survival. The malignant cells in DLBCL often express B-cell markers such as CD20 and CD79a. The aggressive nature of DLBCL is due to its rapid growth rate and high proliferation index, making it a common cause of lymphoma-related mortality in adults.
**Why Each Wrong Option is Incorrect**
**Option A:** Adult T-cell leukemia/lymphoma (ATLL) is a rare and aggressive T-cell lymphoma caused by the human T-cell leukemia virus type 1 (HTLV-1). It is more common in certain regions, such as Japan and the Caribbean, and is associated with a poor prognosis.
**Option B:** Hodgkin lymphoma is a type of lymphoma characterized by the presence of Reed-Sternberg cells, which are distinct from the malignant cells found in DLBCL. Hodgkin lymphoma is less common than DLBCL and often presents with a more indolent course.
**Option D:** Follicular lymphoma is a type of non-Hodgkin lymphoma characterized by the presence of small, cleaved lymphocytes. It is often indolent and can be associated with a favorable prognosis, particularly in patients with early-stage disease.
**Clinical Pearl / High-Yield Fact**
DLBCL is a heterogeneous disease, and its prognosis and treatment response can vary depending on the expression of specific molecular markers, such as MYC and BCL-2. The International Prognostic Index (IPI) is a widely used scoring system to predict the prognosis of patients with DLBCL.
**β Correct Answer: C. Diffuse large B-cell lymphoma (DLBCL)**