Solitary fibrous tumors are rare neoplasms, most commonly involving th
e pleura, recently described in various other locations. We report a s
olitary fibrous tumor of the right adrenal gland in a 42-year-old woma
n, discovered incidentally during abdominopelvic ultrasonographic exam
ination. Pathologic and immunohistologic features of the tumor were id
entical to those of other solitary fibrous tumors. Three-quarters of t
his unencapsulated infiltrating tumoral mass presented foci of hemorrh
age and were made of small, round, epithelioid-like cells that express
ed the CD34 antigen more weakly than do the typical spindle cells usua
lly observed in solitary fibrous tumors. Despite hemorrhage and poor l
imitation, the tumor behaved in a innocuous manner; the mass remaining
unchanged for more than 5 years before the patient agreed to surgical
intervention, which was recommended because of a sudden enlargement o
f the mass.