- Hum Pathol. 1990
Jun;21(6):624-9.
- Variable expression of leucocyte-common
(CD45) antigen in CD30 (Ki1)-positive anaplastic large-cell
lymphoma: implications for the differential diagnosis between
lymphoid and nonlymphoid malignancies.
Falini B, Pileri S, Stein H, Dieneman D, Dallenbach F, Delsol G,
Minelli O, Poggi S, Martelli MF, Pallesen G, et al.
Department of Internal Medicine, University of Perugia, Italy.
Monoclonal antibodies (mAbs) directed against the leucocyte
common (CD45) antigen have been proposed as a useful tool for
the differential diagnosis between malignant lymphomas (CD45+)
and poorly differentiated nonhemopoietic tumors (CD45-). Thanks
to the availability of mAbs directed against fixative-resistant
epitopes of the CD45 molecule, this distinction can now easily
be made even in routinely processed tissues. However, a small
percentage of morphologically poorly defined neoplasms are
difficult to diagnose even with the help of immunohistochemistry.
The investigators report that 63 out of 165 anaplastic
large-cell (ALC) lymphomas did not show any reactivity for the
CD45 antigen in paraffin sections. In routine biopsies, the
lymphomatous nature of these cases, most of which had been sent
for consultation, could be always unequivocally established by
demonstrating negativity for cytokeratins (mAb KL1) and clear
dot-like and/or surface reactivity with the Ber-H2 mAb, which is
directed against a fixative-resistant epitope of the lymphoid
cell activation antigen CD30. Strikingly, 54% of the CD45-cases
reacted with mAbs directed against fixative-resistant epitopes
of the T cell-restricted CD45RO antigen (mAb UCHL1) or the
B-restricted molecules CD45RA (mAb 4KB5) and L26 (unclustered).
In order to avoid confusion of ALC lymphomas with anaplastic
nonlymphoid tumors, pathologists must be aware of the existence
of CD30+/CD45- ALC lymphomas, as they can mimic the
above-mentioned malignancies both morphologically (due to the
sinusoidal growth pattern) and phenotypically (due to the
expression of EMA). The investigators conclude that the combined
use of mAbs directed against fixative-resistant epitopes of the
CD30, CD45RO, CD45RA, and L26 antigens and cytokeratins is
essential for the correct diagnosis and treatment of these
equivocal cases.
PMID: 1693592 [PubMed - indexed for MEDLINE]
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