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Keywords:

  • kidney;
  • neoplasms;
  • magnetic resonance imaging;
  • renal myxoma

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Case report
  5. Discussion
  6. References

Abstract:  Renal myxomas are rare neoplasms. Only three cases have been convincingly diagnosed as renal myxoma. Here we report an additional case. The case was a 36-year-old man and he was discovered incidentally at the regular health-check for chronic hepatitis B. Computed tomography showed 8 cm low-density tumor in the lower pole of the left kidney. The tumor was slightly enhanced by contrast agents. Magnetic resonance imaging revealed the tumor as low intensity on T1-weighted imaging and high intensity on T2-weighted images. The tumor was enhanced by gadrinium enhancement homogeneously. The resected kidney contained semitranslucent, gelatinous, tan mass within the lower pole of the kidney. The microscopic examination showed the typical appearance of a myxoma, which consisted of large amounts of myxoid material containing a few uniformly scattered spindle cells The tumor cells showed immunoreactivity for vimentin but not for S-100 protein, epithelial membrane antigen, cytokeratin, alpha smooth muscle actin.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Case report
  5. Discussion
  6. References

Renal myxomas are rare neoplasms that have been reported three times as case reports.1,2 We report an additional case carried out by radical nephrectomy because of suspected presence of a malignant renal tumor. We show the preoperative imagings of computed tomography (CT), magnetic resonance imaging (MRI) and angiography of the case with pathological findings.

Case report

  1. Top of page
  2. Abstract
  3. Introduction
  4. Case report
  5. Discussion
  6. References

A 36-year-old man was referred to the National Defense Medical College Hospital for assessment of a left renal tumor that was found at the regular health check for chronic hepatitis B. The CT scan showed an 8 cm low-density tumor in the lower pole of the left kidney. The tumor was slightly enhanced by contrast agents (Fig. 1a). Magnetic resonance imaging (MRI) revealed the tumor as low-intensity on T1-weighted imaging and high-intensity on T2-weighted images. The tumor was enhanced by gadrinium homogeneously. There were no evident findings of calcification, necrosis and hemorrhage on MRI (Fig. 2). The urine culture and the cytologic test were normal. The routine chemistry and the hematologic assessments produced normal results. Selective angiography revealed the tumor to be hypovascular (Fig. 1b). The left radical nephrectomy was carried out because of suspected presence of a malignant renal tumor. On sagittal section, a 9 cm × 7 cm × 6 cm, semitranslucent, gelatinous, tan mass was noted within the lower pole of the kidney (Fig. 3a). The microscopic examination revealed the typical appearance of a myxoma, which consisted of large amounts of myxoid material containing a few uniformly scattered spindle cells (Fig. 3b). The tumor cells showed immunoreactivity for vimentin, but not for S-100 protain, epithelial membrane antigen, cytokeratin, alpha smooth muscle actin. The patient recovered without incident.

image

Figure 1. (a) The angiography shows a hypovascular tumor in the lower part of the left kidney. (b) The sagittal view of the left kidney showes an encapsulated mass of glistening tan tissue that occupies the lower pole. (c) The microscopic appearance shows characteristic features of myxoma, loose connective tissues, scattered stellate cells, and stromas with remnants of mucoid material.

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image

Figure 2. (a) T1-weighted image shows a low intense renal mass. (b) T2-weighted image shows a hyper intense renal mass. (c) Fat suppressed T1-weighted image enhanced by gadrinium shows a heterogenously enhanced tumor.

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image

Figure 3. (a) On sagittal section, a 9 cm × 7 cm × 6 cm, semitranslucent, gelatinous, tan mass was noted within the lower pole of the kidney. (b) The microscopic examination showed the typical appearance of a myxoma that consisted of large amounts of myxoid material containing a few uniformly scattered spindle cells.

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Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Case report
  5. Discussion
  6. References

Myxomas are neoplasms that grossly and microscopically resemble primitive mesechyme. The heart, skin, soft tissues and bones are the few sites in which myxomas are currently believed to occur. Renal myxomas are rare neoplasms. Between 1887 and 1995, nine case reports of renal myxoma were published. Melamed et al.2 reviewed the nine cases and assumed only three of the nine are pure renal myxoma, including their two cases (Table 1).1,2 The remaining cases exhibit features of sarcoma, fibroepithelial polyp, or myxolipoma. Our case might be the fourth case of pure renal myxoma. The renal myxoma is considered a benign fibroblastic tumor because the cellular components are devoid of pleomorphism and nucleoli and mitotic figures are not evident. It differs from related fibroblastic tumors such as the small capsular fibroma and renomedullary interstitial tumor in that it attains a larger size. Myxoid change has also been found in sarcomatoid renal cell carcinoma but these changes are usually focal. It is very important to recognize the existence of a renal myxoma, to avoid confusing this benign tumor with the malignant neoplasms with secondary myxoid features.

Table 1.  Clinical and pathological data of four cases of renal myxoma
AuthorsAge/sexPresenting symptomGross descriptionMicroscopic features
Shenansky and Gillenwater162/malePainless hematuria × 6 monthGelatinous lower pole mass; 4 cm × 4 cm × 2 cmScattered stellate cells in a delicate mucoid connective tissue
Melamed et al.252/femaleRenal colic on right because of a calculusGelatinous lower pole mass; 7 cmSpindle and stellate cells in a myxoid matrix
Melamed et al.68/femaleAsymptomaticGlistening upper pole mass: 10 cmPaucicellular myxoid stroma with occasional slender spindle cells
Present case36/maleAsymptomaticGelatinous lower pole mass; 9 cm × 7 cm × 6 cmSpindle and stellate cells in a myxoid matrix

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Case report
  5. Discussion
  6. References