Year : 2009 | Volume
: 52 | Issue : 4 | Page : 549--551
Leiomyosarcoma of the renal pelvis
Sagar A Dhamne, Nitin M Gadgil, Anita Padmanabhan
Department of Pathology, Lokmanya Tilak Municipal Medical College and General Hospital, Sion, Mumbai 400022, India
Nitin M Gadgil
6, Malhar, Anushaktinagar, Mumbai-400 094
Leiomyosarcomas are rare malignant tumors of the kidney. They may arise from the renal capsule, renal vein, renal pelvic musculature or renal parenchyma. Renal pelvis is an uncommon site of occurrence, with around 10 cases reported in the literature so far. Here we present a 60-year-old male who presented with increased urinary frequency, lower limb weakness, anorexia and weight loss. Imaging showed a right renal mass. A renal cell carcinoma was suspected clinically. A right nephrectomy was performed, which showed a large circumscribed mass in the hilar region. Histology revealed a tumor mass arising from the renal pelvis. The tumor was composed of spindle cells arranged in fascicles. Immunohistochemistry showed tumor cells to be positive for smooth muscle actin (SMA) and desmin (Des) and negative for cytokeratin (CK), HMB 45, CD117 (C-kit), and CD34. That confirmed the diagnosis of leiomyosarcoma.
|How to cite this article:|
Dhamne SA, Gadgil NM, Padmanabhan A. Leiomyosarcoma of the renal pelvis.Indian J Pathol Microbiol 2009;52:549-551
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Dhamne SA, Gadgil NM, Padmanabhan A. Leiomyosarcoma of the renal pelvis. Indian J Pathol Microbiol [serial online] 2009 [cited 2020 May 28 ];52:549-551
Available from: http://www.ijpmonline.org/text.asp?2009/52/4/549/56161
Renal leiomyosarcomas are rare but aggressive tumors arising from the renal capsule, renal vein, pelvic musculature or the renal parenchyma.  They are the commonest type of sarcomas, accounting for 50-60% of all the sarcomas arising in the kidney.  However, leiomyosarcomas constitute only 0.5-1.5% of all renal malignancies.  Renal pelvis is the least common site of occurrence of renal leiomyosarcomas. Around 10 cases have been reported in the literature till date.  Complete surgical extirpation is the treatment of choice.  Diagnosis is usually postoperative and requires a thorough sampling of the tumor to rule out an epithelial component.
A 60-year-old male presented with increased urinary frequency, lower limb weakness, anorexia and weight loss. A computed tomography (CT) scan of the abdomen and pelvis revealed a large solid mass arising from the right kidney measuring 9 x 8.3 x 6.2 cm. The mass showed isodense as well as hyperdense areas and heterogeneous contrast enhancement. The mass was seen to be compressing the renal pelvis and the ureter. The renal vein and the inferior vena cava were visualized as being uninvolved. A clinical diagnosis of renal cell carcinoma was made and a right nephrectomy was performed.
Grossly the specimen weighed 520 g, and consisted of kidney and the mass, arising at the hilum. Externally the mass was bosselated, and measured 10 x 8 x 5.6 cm. The renal vein was seen stretched over the mass. The cut surface showed the mass to be circumscribed, solid, white, firm in consistency with a whorled appearance and focal areas of necrosis. The mass was separate but in close proximity to the kidney parenchyma and seen to be arising from the renal pelvis. It was compressing the ureter [Figure 1]. Histology of the mass revealed tumor arising from the pelvic musculature, composed of spindle cells arranged in interlacing fascicles, with elongated, plump, hyperchromatic nuclei and eosinophilic cytoplasm. One to two mitotic figures were noted per 10 high-power fields. Focal areas of abrupt coagulative necrosis and few bizarre cells were also seen [Figure 2]A and B. Immunostaining showed tumor cells with diffuse cytoplasmic positivity for smooth muscle actin (SMA, [Figure 2]C) and desmin (Des). They were negative for immunostaining for cytokeratin (CK, [Figure 2]D), HMB 45, CD 117 (C-kit) and CD 34. The section from kidney revealed only an infarct. Considering the low mitotic rate (one to two mitotic figures per 10 Hpf), focal necrosis (  A female predominance has been reported. There have been approximately twice as many women as men with most patients presenting in the fourth through sixth decades of life.  Leiomyosarcomas usually present with flank pain, hematuria (microscopic or macroscopic) and an abdominal mass, thus mimicking renal cell carcinoma.  Other associated symptoms may include frequency of micturition, loss of appetite and weight loss. A few cases have presented with spontaneous rupture.  Radiographic findings are nonspecific and the diagnosis is usually made postoperatively.  Leiomyosarcoma may arise from the renal capsule, renal parenchyma, pelvic musculature, or the main renal vein. 
Grossly leiomyosarcomas are large, solid, grey-white, soft to firm, focally necrotic tumors. Typical morphologic pattern shows alternating fascicles of spindle cells with blunt-ended non-tapering nuclei and eosinophilic cytoplasm. Nuclear pleomorphism, atypia, mitotic figures and necrosis are variably seen. Leiomyosarcomas of the kidney should be differentiated from the sarcomatoid variant of renal cell carcinomas, atypical angiomyolipomas, and genitourinary pacemaker cell tumors. The latter tumors are thought to arise from the Cells of Cajal-like cells which have been identified in the upper as well as the lower urinary tract stroma. , The tumors resemble their counterparts in the gastrointestinal tract (GIST / GIPACT).  Immunohistochemically the tumor cells of leiomyosarcoma are positive for SMA, Des, calponin, and h-caldesmon and negative for antibodies to CK, S-100 protein, HMB-45 and CD117 (C-kit).  The angiomyolipomas will show HMB-45 positivity while the sarcomatoid variant of renal cell carcinoma will be CK positive. CD 117 and CD 34 positivity will be seen in the genitourinary pacemaker cell tumors. A thorough sampling of the tumor is necessary to rule out any epithelial component as the sarcomatoid variant of renal cell carcinoma may show a predominant spindle cell population and forms the closest differential. Grignon et al.  in their study suggested that to make a diagnosis of a primary renal sarcoma the following criteria should be met: 1) the patient must not have or have had a sarcoma elsewhere to rule out metastasis, 2) gross must be compatible with origin in the kidney rather than involvement due to retroperitoneal sarcoma 3) sarcomatoid renal cell carcinoma must be excluded.
Small size (  Histologic grade of the tumor is assigned based on the mitotic count, necrosis and nuclear pleomorphism. , Grignon et al.  demonstrated correlation between DNA ploidy and tumor grade. However, no correlation with the outcome of the tumor was found in their study. Renal leiomyosarcomas are aggressive tumors with a five-year survival rate of 29-36%; most patients dying within one year of diagnosis.  High-grade sarcomas often metastasize, the lungs being the primary site of spread, and prognosis is poor.
In the study by Deyrup et al.  the majority of the renal leiomyosarcomas were intermediate or high-grade with correspondingly poor prognosis. Kendal WS  has suggested that when leiomyosarcomas were analyzed separately, the major determinants to overall survival were stage and age at diagnosis.
Complete surgical extirpation is the treatment of choice.  Irradiation and chemotherapy do not appear to alter the course of the disease.  However, a few authors have suggested use of adjuvant therapy for these aggressive tumors.
Leiomyosarcomas of the kidney are rare, aggressive tumors. Preoperative diagnosis is difficult. The sarcomatoid variant of renal cell carcinoma is a close differential and hence epithelial component should be ruled out by thorough sampling. Immunohistochemistry is a useful ancillary tool for diagnosis. Size of the tumor, age of the patient, histologic grade, and presence or absence of metastases are important prognostic factors. However, the overall prognosis still remains poor.
We thank Dr. Anita Borges, Consultant Pathologist, Raheja Hospital, Mumbai for helping us with the immunohistochemistry.
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