Which type of lymphoma is characterized by disease cells in solid masses in lymph nodes?

Small lymphocytic lymphoma is characterized by the presence of neoplastic cells that accumulate in solid masses within the lymph nodes, leading to the manifestation of lymphadenopathy. This lymphoma is considered an indolent form of B-cell non-Hodgkin lymphoma and primarily involves the proliferation of small, mature lymphocytes.

Histologically, small lymphocytic lymphoma displays a high degree of homogeneity, with small, round lymphocytes clustered in lymphoid tissue, typically in a diffuse pattern or forming nodular structures. Unlike chronic lymphocytic leukemia, which involves a similar type of cell but is primarily characterized by the presence of these cells in the blood and bone marrow, small lymphocytic lymphoma is defined by its solid lymph node involvement.

The other types mentioned, such as chronic lymphocytic leukemia and acute lymphoblastic leukemia, do not primarily present with solid masses in lymph nodes, and Hodgkin lymphoma is distinguished by the presence of Reed-Sternberg cells, which are not characteristic of small lymphocytic lymphoma. Thus, the defining feature of small lymphocytic lymphoma as involving solid masses of disease cells in lymph nodes makes it the correct answer.