A second peak is seen again in patients over 40 years of age. The distinction from acute lymphoblastic leukemia is in part arbitrary, based on the degree of marrow involvement. Lymphoblastic lymphoma usually presents supradiaphragmatically in the cervical, supraclavicular, and axillary regions. Over half the patients have an anterior mediastinal mass, which may cause acute chest symptoms. The marrow is focally involved in about half the cases, and other extranodal sites are common.
Untreated patients do dismally.
Lymphoblastic lymphoma cells are larger than benign lymphocytes but smaller than histiocytes. The nuclei are convoluted or regular in contour and contain finely granular, dark chromatin and at most inconspicuous nucleoli. The lymphoma often extends into perinodal soft tissue. This is appropriate for an early lymphoid cell, which requires that enzyme to rearrange its immune genes. These display the earliest T-cell markers CD7 and CD2 in addition to later markers depending on the lymphoma's maturity.