<s>[INST] context: Lymphocytes positive for CD 19, CD20, CD23, CD5 suggest the diagnosis of chronic lymphocytic leukemia/small lymphocytic lymphoma.
In CLL/SLL larger lymphocytes show high mitotic activity and form proliferation centre.

Chronic lymphocytic leukemia (CLL), small lymphocytic lymphoma (SLL).

CLL and SLL are identical neoplasm/arise due to an abnormal neoplastic proliferation of B cells.
CLL involves primarily bone marrow and blood, while SLL involves lymph nodes

Morphology of CLL/SLL

The tumor cells of CLL are small B lymphocytes.
Leukemic cells have the morphological appearance of normal small to medium sized lymphocytes with clumped chromatin, inconspicuous nuclei and a small ring of cytoplasm.
The lymph node architecture is diffusely effaced by these tumor cells.
These cells are mixed with variable numbers of larger cells called prolymphocytes.
In many cases, prolymphyocytes gather together focally to form as proliferation centers, so called because they contain relatively large number of mitotic activity.
When present proliferation centers are pathognomonic for CLL/SLL.
In CLL, the peripheral blood contains increased numbers of small, round lymphocytes with scant frequently disrupted in the process of making smears, producing So called smudge cells..


Markers of CLL tumor cells

CLL is a tumor of mature -cells, therefore it expresses the B-cell markers such as CD19, CD20 and surface IgM and IgD.
In addition CD23 and CD5 are also present (In contrast to mantle cell lymphoma which is positive for CD5 but negative for CD23). [/INST] question: A 48 year old woman was admitted with a history of weakness for two months. On examination, cervical lymph nodes were found enlarged and spleen was palpable 2 cm below the costal margin. Her hemoglobin was 10.5 g/dl, platelet count 2.7 × 109/L and total leukocyte count 40 × 109/ L, which included 80% mature lymphoid cells with coarse clumped chromatin. Bone marrow revealed a nodular lymphoid infiltrate. The peripheral blood lymphoid cells were positive for CD 19, CD5, CD20 and CD23 and were negative for CD 79 B and FMC-7.The histopathological examination of the lymph node in this patient will most likely exhibit effacement of lymph node architecture by - | options: A: A pseudofollicular pattern with proliferation centers B: A monomorphic lymphoid proliferation with a nodular pattern C: A predominantly follicular pattern D: A diffuse proliferation of medium to large lymphoid cells with high mitotic rate | answer: A </s>