Renal Neoplasia: Diagnostic Problems and Recently Recognized Entities
Case 7 -
Primary Renal Synovial Sarcomas
John N Eble, M.D.
Holger Moch, M.D.
47 year old woman with abdominal pain. CT showed a 12 cm
measuring tumor with cysts. Macroscopic findings: The tumor was solid
with multiple areas of hemorrhage, necrosis and cyst-formation.
Primary renal synovial sarcomas
Synovial sarcoma of the kidney is a recently recognized entity which is characterized by a specific
morphology and specific cytogenetic characteristics. They consist of spindle cells and frequently have
large cysts. Many cases show local recurrence after nephrectomy. Most cases are diagnosed between the
ages of 20 and 50 years. Microscopically, tumors are characterized by monomorphic plump spindle cells.
The cysts are lined by mitotically inactive epithelial cells without striking cellular atypia. The
tumors have been previously described as embryonal sarcoma of the kidney. There is a slight male
predilection (1.6 : 1). No bilateral tumors were identified yet.
The spindle cells are immunoreactive for EMA, CD56 and sometimes for CD99. They are non-reactive for
desmin, actin, S100 and cytokeratins. The cyst epithelium is cytokeratin positive. Synovial sarcoma is
cytogenetically characterized by the translocation t(X;18)(p11.2/q11.2), generating a fusion between the
SYT gene on chromosome 18 and one member of the SSX gene family (SSX1;SSX2; SSX4) on chromosome X.
Molecularly confirmed primary synovial sarcomas of the kidney have demonstrated the characteristic SYT-SSX gene fusion. In contrast to soft tissue synovial sarcoma where the SYT-SSX gene fusion is more common than the alternative SYT-SSX2 form, the majority of renal synovial sarcomas have so far demonstrated
the SYT-SSX2 gene fusion. There is a tendency for a predominance of
monophasic spindle morphology of these tumors in the kidney and there are more rarely biphasic tumors.
Although prognostic data are limited, there are case reports describing tumors which have responded to
chemotherapy. However, recurrence is common.
Taken together, primary renal synovial sarcoma is a distinctive tumor entity, which should be
considered especially in young adults.
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- Argani P, et al. Primary renal synovial sarcoma: molecular and morphologic delineation of an entity
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- Moch H, et al. Primary renal synovial sarcoma. A new entity in the morphological spectrum of spindle
cell renal tumors]. Pathologe 24: 466-72, 2003.