Background/Aims: The authors report on an extremely rare case of a rec
urrent myogenic tumor of renal origin presented exclusively with gastr
ointestinal signs and symptoms resulting from duodenal invasion. Patie
nts and Materials: A 49-yr-old woman was admitted for epigastric pain
and recent history of melenae. She had been submitted to right nefrect
omy due to a smooth muscle tumor five years ago. Results: Pathology de
scribed it as a bizarre leiomyoma. Diagnostic procedures showed lobula
ted and ulcerated lesions in the duodenum, a nodule within the anterio
r abdominal wall, a large neoplasm fulfilling the right renal loca and
invading the duodenum, and another nodule at the left kidney. Histolo
gical features of all tumors were similar to those seen in the primary
renal tumor. The abdominal wall nodule was the only resectable lesion
. Although biopsies taken initially from the duodenal lesions failed t
o reveal smooth muscle tissue, they were repeated one year later and d
isclosed duodenal invasion from a leiomyosarcoma. Conclusion: This ext
remely rare case illustrates the striking disagreement between patholo
gical diagnosis and clinical course of smooth muscle tumors that somet
imes occur.