Untitled Quiz

Malignant Tumors of Lymphoid Tissue

• Characterized by abnormal proliferation of B and T cells in lymphoid tissues.
• Two main types: Leukemia (bone marrow and peripheral blood involvement) and Lymphoma (lymph nodes/other organs).
• Plasma cell myeloma is confined to bones, appears as discrete masses, does not involve lymph nodes or peripheral blood.
• Neoplastic proliferations are monoclonal; reactive conditions are polyclonal.
• Lymphoid neoplasms can disrupt normal immune function, causing immunodeficiency and autoimmunity.

Non-Hodgkin’s Lymphoma and B-Cell Neoplasms

• Precursor B-cell neoplasms include Acute Lymphoblastic Leukemia (ALL).
• Mature B-cell neoplasms include Small Lymphocytic Lymphoma (SLL) and Chronic Lymphocytic Leukemia (CLL).
• CLL: most common leukemia in adults with a median age of 70 years; presents as painless generalized lymphadenopathy.
• 80% of CLL cases involve bone marrow at diagnosis; 30-40% may progress to Diffuse Large B-cell Lymphoma (DBLCL).

Follicular Lymphoma

• Morphology: Vaguely nodular appearance with disrupted architecture and regions of neoplastic cells (centrocytes and centroblasts).
• Centrocytes are slightly larger, with angular cleaved nuclei; centroblasts are larger with fine chromatin and prominent nucleoli.
• Immunophenotyping commonly shows B-cell markers and germinal center markers (CD10, BCL6).
• Characterized by a specific translocation (t(14;18)) resulting in BCL2 gene overexpression.

MALT-Type Lymphoma (Extranodal Marginal Zone Lymphoma)

• Associated with chronic inflammation or autoimmune disorders, such as Helicobacter gastritis or Hashimoto thyroiditis.
• Persistent at the site of origin; withdrawal of inciting cause can lead to tumor regression.
• Morphological features: small round to irregular cells infiltrating involved tissues, often forming lymphoepithelial lesions.

Mantle Cell Lymphoma

• Composed of naive B cells resembling those in mantle zones of normal lymphoid follicles.
• Primarily affects men over 50 years, commonly presenting with fatigue and lymphadenopathy.
• Associated with a specific translocation (t(11;14)) leading to cyclin D1 overexpression, resulting in an aggressive disease with a median survival of 4 to 6 years.

Diffuse Large B-cell Lymphoma (DLBCL)

• Most common lymphoma type in adults; presents typically in the 60s age range.
• Rapidly enlarging symptomatic mass may occur; common extranodal sites include the gastrointestinal tract.
• Associated with mutations/rearrangements of the BCL6 gene, often arising from follicular lymphomas with t(14;18) translocation.
• Morphology: large neoplastic B cells (3-4 times size of resting lymphocytes) with rare mitoses, resembling centroblasts or immunoblasts. Immunophenotyping includes CD10 and CD20.

Subtypes of DLBCL

• EBV-associated lymphomas common in AIDS, iatrogenic immunosuppression, and elderly patients.
• Kaposi sarcoma herpes virus (HHV-8) linked to primary effusion lymphomas.
• Mediastinal large B-cell lymphoma is prevalent in young women, with a propensity for abdominal and CNS spread.

Prognosis

• DLBCL without treatment is aggressive and rapidly fatal; intensive therapy can lead to complete remission or potential cure.