Metachronous Retroperitoneal Leiomyosarcoma and Liposarcoma:
A Case Report
Ping-Hsuan Yu1, Shing-Hwa Lu1,2,3,4, William J.S. Huang1,2,3
1 Department of Urology, Taipei Veterans General Hospital;
2 Department of Urology, School of Medicine, National Yang-Ming University;
3 Shu-Tien Urological Science Research Center;
4 Taoyuan Branch, Taipei Veterans General Hospital
Introduction: Leiomyosarcoma and liposarcoma, which are originated from smooth muscle and adipose respectively, are two possible neoplasms diagnosed at the retroperitoneum. Surgical resection remains the mainstay for curation of the two diseases. Metachronous presence of the two pathological entities on one patient is quite rare. Here we would like to report a case with kidney leiomyosarcoma diagnosed at first and followed with ipsilateral retroperitoneal liposarcoma after one-and-a-half-year follow-up.
Case report: A 66-year-old woman has a medical history of gastric adenocarcinoma, pT1bN0, stage IA. She underwent radical subtotal gastrectomy and Roux-en-Y gastrojejunostomy in 2011. She was under regular follow-up after the surgery without disease recurrence. However, in the annual follow-up at local institute in late 2018, abdominal computed tomogram revealed a 3.9cm exophytic heterogenous mass over left kidney upper pole without lymphadenopathy or distant metastasis. Renal cell carcinoma was first impressed. The patient was then referred to our hospital for surgery. At clinic, the patient mentioned about left flank intermittent discomfort within recent three months.
Robot-assisted partial nephrectomy was performed in February 2019. The excised tumor was whitish, 3.9 x 2.7cm in size. It was confined by capsule and without sinus invasion or collecting system invasion. The pathology of the tumor showed leiomyosarcoma, low grade. Immunohistochemically, the tumor was positive for SMA while negative for CD34 and STAT6. The tumor involved the excisional margin.
She was doing well after the surgery. Because of the positive surgical margin microscopically, we applied intensive follow-up protocol. Computed tomogram in June 2020 revealed a newly identified enhancing soft tissue lesion at left perirenal space, sizing 1.2cm. Initially, tumor recurrence was impressed. The patient was admitted again, and laparoscopic tumor excision was performed in August 2020. A fat-containing tumor over posteriolateral to left peri-renal region was found. However, the pathology showed well-differentiated liposarcoma. Tumor cells were immunoreactive for MDM2 and CDK4. Immunostains for CDK4 and MDM2 were also applied on the patient's previous renal leiomyosarcoma, which showed negative results. Therefore, the two tumors were of different histology.
Conclusion: Soft tissue sarcomas only account for less than 1% of all neoplasms in humans. Metachronous sarcomas with distinct histology in one patient are uncommon. Since most of the related case reports are about tumors in extremities, metachronous sarcomas over retroperitoneum are extremely rare. To our knowledge, this might be the first to report metachronous leiomyosarcoma and liposarcoma over retroperitoneum. Repeated aggressive surgical intervention is still pivotal for disease control. Multiple primary tumors may result from several hypotheses, including environmental exposure, tumor with polyclones or pluripotential stem cells.