A 21-year-old male patient had localized papules on the chest and arms
. Biopsy of a lesion showed it to be a malignant lymphoid neoplasm, an
d immunohistochemical studies confirmed a lymphoblastoma origin. Aberr
ant lymphoid cells were noted in the cutaneous blood vessels, but simu
ltaneous examination of the peripheral blood showed no evidence of leu
kemia. One month elapsed before observable leukemic cells were found i
n the blood and sternal marrow, confirming the diagnosis of acute lymp
hocytic leukemia. Examination of a cutaneous biopsy specimen led to ea
rly diagnosis of the disease.