Abstract
Flow cytometry is the preferred method of
diagnosing and immunophenotyping acute lymphoblastic
leukemia (ALL). However, there are situations in
which immunohistochemical staining (IH) of bone
marrow trephine biopsy specimens can be used to
provide immunophenotypic information. To evaluate the
use of IH and to confirm its value in diagnosing and
typing of ALL, we studied 50 cases of denovo ALL that
were previously classified into pre B, T and B by
morphologic, cytochemical and FC methods. Paraffin
embedded bone marrow trephine biopsies sections were
stained using a panel of antibodies,namely,
myeloperoxidase (MPO), terminal deoxynucleotidyl
transferase (TdT), CD10, CD20, CD79a, CD3. The cases
included 37 pre BALL, 10 T ALL and 3 mature BALL.
TdT was the most commonly expressed antibody and
was positive in 41 of 50 cases of ALL (82%) and in 95%
of pre B ALL cases. CD79a and CD10 were positive in
68% and 65% of pre B ALL cases, respectively. CD79a
showed similar positivity in B ALL cases (66%). CD 20
was positive in 66% of mature B ALL cases but less
positive in pre B ALL (22%). CD3 was positive in 70%
of T ALL cases and negative in other ALL subtypes. All
of the cases were negative for MPO. Diagnosis and immunophenotyping of acute lymphoblastic leukemia is
possible using immunohistochemical staining of bone
marrow trephine biopsies.