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2012, Volume 28, Number 1, Page(s) 076-079
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DOI: 10.5146/tjpath.2012.01102
Myxoma of the Renal Sinus: Case Report and Literature Review
Ümran YILDIRIM1, Havva ERDEM1, Ali KAYIKÇI2, Ali Kemal UZUNLAR1, Ali TEKİN2, Mehmet Akif KUZEY1
1Department of Pathology, Düzce University, Faculty of Medicine, DÜZCE, TURKEY
2Department of Urology, Düzce University, Faculty of Medicine, DÜZCE, TURKEY
Keywords: Myxoma, Kidney, Renal neoplasms
Abstract
Myxoma is a rare mesenchymal tumor and it is mainly seen in heart and skin. Renal myxoma is extremely rare. To date, eleven cases of kidney myxomas have been reported in the literature. One of them is myxoma of the renal sinus. Our case was an 82-year-old man admitted to our hospital symptoms related to the urinary tract obstruction. Abdominal computerized tomography revealed a solid, hypodense mass 9 cm in diameter infiltrating the renal parenchyma in the renal pelvis. The patient underwent nephrectomy. The resected kidney contained gelatinous tumor with indistinct borders. The tumor was composed of slender, bland, spindle-shaped cells with large amounts of mucoid material. Tumor cells were positively stained with vimentin, focally stained positive for smooth muscle actin and had negative reactivity for S-100 protein, epithelial membrane antigen and pancytokeratin. Herein we report the second case of renal myxoma arising from the renal sinus.
Introduction
Renal pelvic tumors represent 5-10% of all the renal tumors. Almost 90% of these are transitional cell carcinomas1. Mesenchymal neoplasms arising in renal pelvis are fairly uncommon. Most of these neoplasms originate from vascular or smooth muscle tissue and eighty-one cases of benign neoplasms and 40 sarcomas were identified in the literature.

A classification of reported mesencymal neoplasm is presented in Table I. Although benign mesencymal tumors are more frequently located in renal pelvis, malignant tumors are located in ureter2.


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Table I: Classification of mesenchymal neoplasms of renal pelvıs and ureter

Myxomas are relatively uncommon soft tissue neoplasms. This tumor can be found in various sites in the body including the skin, heart, soft tissue, head and neck. Myxoma of the kidney is extremely rare. To date, eleven cases of pure myxoma reported in the literature (Table II). Only one of them originated in renal pelvis and others were situated in renal parenchyma and capsule. Our case is the second renal myxoma arising in the renal sinus.


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Table II: Clinicopathologic features of reported cases

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  • Abstract
  • Introduction
  • Case Presentation
  • Disscussion
  • References
  • Case Presentation
    An 82-year-old male patient was admitted with the complaints of dysuria, flank pain and urinary obstruction for two years. He had been treated with the diagnosis of tuberculosis and had no urinary system complaints before. His physical examination was unremarkable. Laboratory values were within the normal limits. Abdominal USG revealed a mass, 9 cm in diameter, solid with heterogeneous echo in the left renal pelvis. CT scan showed a low density mass (Figure 1). Fine needle aspiration was performed and resulting suspicious cytology for malignancy. Patient underwent a left radical nephrectomy.


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    Figure 1: Computed Tomograhy image without contrast media in prone position showing hyperdense biopsy needle entering hypodense mass in the left kidney.

    Nephrectomy specimen weighed 330 g together with perirenal fat tissue. On sagittal section, the pelvis of the left kidney contained a 9x6x5 cm semitranslucent, gelatinous tumor mass. Tumor involved the renal parenchyma. Other pathologic findings such as calculi, hidronephrosis were not detected on gross examination of the renal tissue (Figure 2). Microscopically, the tumor was composed of hypocellular and hypovascular myxoid stroma. Tumor cells were spindle, fibroblast like, oval and stellate shaped. Nuclear atypia and mitosis were not demonstrated (Figure 3). Tumor was invading renal parenchyma. The tumor and renal parenchyma were indistinct. Ureter was intact. There was no pathological finding in non-tumoral areas. The myxoid stroma was stained with alcian blue and tumor cells were positively stained with vimentin (Figure 4), focally stained positive with smooth muscle actin (SMA), and negatively stained for S100 protein, epithelial membrane antigen (EMA), and pancytokeratin. Final diagnosis was myxoma of the renal sinus according to gross, microscopic and immunohistochemical findings.


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    Figure 2: Tumor tissue 9 cm in diameter demonstrated in the left kidney. The surface of the greenish mass had a semitranslucent appearance and the mass was composed of a gelatinous, stringy mucoid material.


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    Figure 3: Photomicrograph shows tumor tissue including scattered stellate cells in the myxoid material (H&E, x200).


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    Figure 4: Tumor cells positively stained with vimentin (x400).

  • Top
  • Abstract
  • Introduction
  • Case Presentation
  • Disscussion
  • References
  • Discussion
    Various benign mesenchymal tumors of the renal pelvis have been reported in the literature1-3. Some of these are hemangioma (40 cases), leiomyoma (10 cases), schwannoma-neurofibroma (2 cases), solitary fibrous tumor (2 cases), glomus tumor (1 case). Malignant mesenchymal tumors composed approximately 30% of mesenchymal neoplasms arising in renal pelvis1-3. A total of 38 malignant mesencymal tumor cases have been reported in the literature up to date. Ninety percent of these are smooth muscle origin. These include leiomyosarcoma (12 cases), malignant schwannoma (1 case), angiosarcoma, osteosarcoma, chondrosarcoma and rhabdomyosarcoma1-3. Myxoma has not been situated in classification of mesenchymal tumors of the kidney in textbooks yet.

    Myxoma has been described first by Virchow in 18634-6. Although myxomas show similar microscopic appearance, they exhibit different behavioral and clinicopathological course4-6. It is suggested that this difference is based on molecular abnormalities4-6.

    Myxomas located in different sites of the body have different molecular mutations and other abnormalities4-6.

    Cells of myxoma considered to be originated from fibroblast like primitive mesencymal cells. These cells are similar to fibroblast but they lost the capacity to polymerize collagen. Some authors believe that myxoma is a myxoid change of some mesenchymal tumors such as leiomyoma and degenerative changes seen in adipose tissue in brown atrophy of the heart7-9. The others believe that the uniform cellular component throughout the lesion supports a neoplastic nature rather than a regressive change within the pre-existing tumor7-9.

    Clinicopathological data of the reported twelve cases are shown in Table 2. Data were available in ten of the twelve cases including our case3,4,7-13. Six of the patients were male and the age at the diagnosis ranged from 27 to 82 years (mean 51,3). Our case is the most elderly one among these cases. Tumor size varied from 4 to 28 cm (mean 12,2 cm). Tumors were located in lower pole of the kidney in four cases, upper pole in one case, entire kidney in one case and middle pole in three cases except the case reported by Nisimoto K in 1996. Our case is the second one located in renal sinus.

    Histopathologic appearance of renal myxomas resembles others located at different sites of the body. The present case showed similar cellular structure with myxoma with the lack of pleomorphism, mitosis and nucleoli.

    Renal myxoma should be differentiated from other benign and malignant mesenchymal tumors such as myxoid neurofibroma, myxoid leiomyoma, perineuroma, myxolipoma, myxoid variant malignant fibrous histiocytoma, liposarcoma, leiomyosarcoma and rhabdomyosarcoma. Renal myxoma can be easily distinguished from sarcoma with the lack of anaplastic features in nephrectomy material. Each benign tumor display characteristic histopathological and immunohistochemistry features8,11,12. Our case did not have different histological areas such as neural, fibrous, leiomyomatous changes.

    The present case was focally stained positive with SMA which reminded leiomyoma possibility in the differential diagnosis. However, specimens which were taken from the tumor did not show any fasciculated spindle cells or bundles that were specific for leiomyoma. Homogeneous structure throughout the sections, focal positive staining with SMA, desmin negativity and loss of parallel alignment of the cells also withdrew us from the diagnosis of leiomyoma16. Our case also differed from myxoid liposarcoma with the lack of lipoblastic differentiation and differed from myxoid lipoblastoma with the lack of atypia, characteristic multilobular pattern and existence in the elderly17,18.

    Cytopathological examination can be performed to distinguish benign tumors from malignancies. We have performed fine needle aspiration accompanied with CT before the surgical procedure and the result showed malignancy potential.

    In conclusion, we described here a very rare type of mesenchymal tumor of the renal sinus. It is important to distinguish this benign entity from malignant tumors that may exhibit secondary myxoid changes due to overtreatment. The treatment of choice is radical nephrectomy. A case cured with enucleation was also reported in the literature but this was not possible in our case due to infiltration of the surrounding renal parenchyma.

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  • Abstract
  • Introduction
  • Case Presentation
  • Discussion
  • References
  • References

    1) Brady JD, Korman HJ, Civantos F, Soloway MS: Fibroepithelial polyp of the renal pelvis: nephron sparing surgery after false positive biopsy for transitional cell carcinoma. Urology 1997, 49: 460-464. [ PubMed ]

    2) Petersen RO, Sesterhenn IA, Davis CJ: Urologic Pathology. 3rd ed., Philadelphia, Lippincott Williams&Wilkins, 2009

    3) Bolat F, Turunc T, Kayaselcuk F, Ulusan S, Bal N: Primary renal myxoma. Turkish Journal of Pathology 2007, 23:160-163

    4) Allen PW: Myxoms is a not single entity: a review of the concept of myxoma. Ann Diag Pathol 2000, 4:99-123. [ PubMed ]

    5) Casey M, Vaughan CJ, He J, Hatcher CJ, Winter JM, Weremowicz S, Montgomery K, Kucherlapati R, Morton CC, Basson CT: Mutation in the protein kinase A RI alpha regulatory subunit cause familial cardiac myxoma and Carney complex. J Clin Invest 2000, 106:R31-R38. [ PubMed ]

    6) Fogt F, Zimmerman RL, Hartmann CJ, Brown CA, Narula N: Genetic alteration of Carney complex are not present in sporadic cardiac myxoma. Int J Mol Med 2002, 9:59-60. [ PubMed ]

    7) Melamed J, Reuter VE, Erlandson RA, Rosai J: Renal Myxoma. a report of two cases and review of the literature. Am J Surg Pathol 1994, 18:187-194. [ PubMed ]

    8) Kundu AK, Chakraborty AK, Chakraborty S: Myxoma of the kidney. J Indian Med Assoc 1995, 93:462-464. [ PubMed ]

    9) Val-Bernal F, Aguilera C, Villagra N, Correas MA: Myxoma of the renal capsule. Pathol Res Pract 2005, 200:835-840. [ PubMed ]

    10) Owari Y, Kondo R, Omori S, Seo T, Suzuki K, Fujioka T: Myxoma of the kidney. Int J Urol 2006, 13:987-989. [ PubMed ]

    11) Nishimoto K, Fukushima M, Hatachi K, Yonehara S, Horiguchi J: Case of the renal myxoma. Jpn J Urol Surg 1996, 9: 1075-1078

    12) Koike H, Hayasi Y, Imanishi M: Case of the renal myxoma. Acta Urol Jpn 2004, 50:128-129

    13) Nishimoto K, Sumitomo M, Kakoi N, Asano T, Hayakawa M: Case of renal myxoma. Jpn. J Urol Surg 2005, 17: 1294

    14) Appel SD, Schoenberg HW: Myxoma of the renal sinus. J Urol 1968, 100:254-255. [ PubMed ]

    15) Shenansky JH, Gillenwater JY: Myxoma of the kidney. Urology 1973, 1:240-242. [ PubMed ]

    16) Goldblum Jr, Weiss SW: Benign Tumors of the Smooth Muscle. In Goldblum JR, Weiss SW. (Eds): Enzinger and Weiss's Soft Tissue Tumors. 4th ed., Philadelphia, Mosby, 2001, 695-726

    17) Goldblum Jr, Weiss SW: Liposarcoma. In Goldblum JR, Weiss SW. (Eds): Enzinger and Weiss's Soft Tissue Tumors. 4th ed., Philadelphia, Mosby, 2001, 571-640

    18) Goldblum Jr, Weiss SW: Benign Lipomatous Tumors. In Goldblum JR, Weiss SW. (Eds): Enzinger and Weiss's Soft Tissue Tumors. 4th ed., Philadelphia, Mosby, 2001, 641-692

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  • Abstract
  • Introduction
  • Case Presentation
  • Discussion
  • References
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