Lymphoblastic Lymphoma

L y m p h o b l a s t i c l y m p h o m a

General

• This type of lymphoma occurs mainly in children and young adults.

• It is considered to be the same disease as acute lymphoblastic leukemia

(ALL) both clinically and morphologically (and both are treated in the

same way).

Morphology

• Pattern: Diffuse.

• Cytology: Medium-sized cells with fine chromatin, scant cytoplasm, high

mitotic rate.

Immunophenotype

• Most cases (70%) T-cell, rest B-cell.

• TdT positive (because tumor cells are blasts)!

Clinical features

• Most patients <20. M>F.

• Often present with mediastinal mass (representing enlarged lymph nodes in

the mediastinal region)

Q. Wait a minute, didn't you say lymphoblastic lymphoma is the same thing as ALL? Then how come here it says that most cases of lymphoblastic lymphoma are T-cell, and on the ALL page, it says that only 15% of cases are T-cell?!

A. How very astute of you! Here's the deal. Although officially (see the REAL classification) ALL and lymphoblastic lymphoma are considered to be the same disease, unofficially (and for the sake of ease when describing a patient's disease) the two are often separated. When a patient has just bone marrow and blood involvement, he/she is often said to have ALL, and when a patient has just lymph node involvement, he/she (usually he) is said to have lymphoblastic lymphoma. Eventually, as the diseases in these two hypothetical patients progress to involve more organs, they will resemble each other more and more.

It just so happens that if you look at tumor cells from patients who present with just lymph node involvement (in unofficial terms, a patient with lymphoblastic lymphoma), those tumor cells are usually T-cell in immunophenotype. And conversely, if you look at tumor cells from patients who present only with blood and/or bone marrow involvement (in unofficial terms, a patient with ALL), those tumor cells are usually B-lineage cells.

So you could say, then, that cases of lymphoblastic lymphoma tend to be T-cell in nature, and cases of ALL tend to be B-lineage in nature. Make sense?