BACKGROUND, Extramedullary involvement is only occasionally observed i
n patients with acute promyelocytic leukemia (APL) but has been said t
o occur more frequently after treatment with all-trans retinoic acid (
ATRA) than after treatment with cytotoxic drugs. In the literature, 37
well-documented cases have been reported. METHODS. The authors report
7 patients with extramedullary APL documented by cytologic, phenotypi
c, and molecular analyses among 120 adult APL patients referred to two
different institutions during a period of 9 years. RESULTS. In this A
PL series, extramedullary disease (EMD) occurred in 7 of 120 cases (5.
8%). The extramedullary sites were the skin in five patients, the cent
ral nervous system in one, and the lymph nodes in one. Molecular analy
sis of the PML/RAR alpha rearrangement was performed on four samples o
f skin and one of CSF; all patients exhibited the same molecular patte
rn in the bone marrow (BM) and EMD sites. Of 120 patients, 61 were tre
ated with ATRA plus chemotherapy and 59 with chemotherapy alone. Relap
ses were observed in 38 patients, 6 of whom had EMD; 1 patient had dev
eloped EMD at the onset of APL. Of the relapsed EMD cases, 2 of 61 pat
ients had received ATRA plus chemotherapy and 4 of 59 had received che
motherapy alone. CONCLUSIONS. There is some controversy as to whether
treatment of APL with ATRA may predispose patients to the development
of extramedullary relapse. The data from this study do not contain evi
dence that EMD may occur more frequently in APL patients treated with
ATRA. Cancer 1998;83:1522-8. (C) 1998 American Cancer Society.