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Keywords:

  • metastasis;
  • parotid gland;
  • renal cell carcinoma.

Abstract

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

Abstract  Renal cell carcinoma metastasis to the parotid gland after tumor nephrectomy is extremely rare. We report a case of solitary parotid metastasis from clear cell renal cell carcinoma in a 59-year-old woman, who presented 10 years after primary treatment. To our knowledge this is the first case in the published literature presenting with solitary parotid metastasis after such a long time. Superficial parotidectomy with preservation of the facial nerve was performed. One year after, the patient developed contralateral multiple kidney tumors and underwent left radical nephrectomy. She is currently on a dialysis program and no additional metastasis has been observed for 18 months.


Introduction

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

Renal cell carcinoma (RCC) has a high metastatic potential and the most common sites for RCC metastasis are the lung, bone, liver, brain and skin.1 Metastasis to the head and neck region are less common, comprising 8–14% of all cases.2 The thyroid gland is the most common site in this region for RCC metastasis and parotid gland metastasis is extremely rare.2 In most cases, parotid metastasis is the initial presenting symptom of the malignancy in the kidney, but can also be observed after tumor nephrectomy.3 The time interval from the removal of the kidney tumor to the appearance of parotid metastasis ranges from several months to years.3 Herein, we present a case of solitary parotid metastasis 10 years after the primary treatment for RCC. To our knowledge, this is the first case in the published literature presenting with parotid metastasis after such a long time.

Case report

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

A 59-year-old woman was referred to the Ear, Nose and Throat Surgery (ENT) Department at Ankara University, Turkey with a slowly growing right preauricular mass present for two months. In physical examination, the mass was mobile, non-tender and painless. There was no facial weakness. The patient's history showed that she had undergone a right radical nephrectomy with a diagnosis of renal cell carcinoma in May 1991. The kidney tumor was 7 cm in diameter. The tumor had invaded the perinephric tissues and had been extended to the Gerota's fascia but not beyond it (Fig. 1). At that moment there was no lymph node or distant metastasis (pT3aN0M0). Parotid ultrasonography revealed a 3 × 3 cm heterogeneous nodular lesion in the right salivary gland (Fig. 2). Fine needle aspiration biopsy of the mass showed a RCC metastasis to the parotid gland. Abdominal ultrasonography, chest radiograph and bone scan demonstrated no local recurrences or distant metastasis other than the parotid gland. In July 2001, the patient underwent an superficial parotidectomy with preservation of the facial nerve.

image

Figure 1. Computerized tomography revealing a kidney tumor 7 cm in diameter on the right side. The tumor invaded the perinephric tissue and has extended to the Gerota's fascia, but was not beyond it.

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image

Figure 2. Parotis ultrasonography revealing a 3 × 3 cm heterogeneous nodular lesion in right salivary gland.

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Pathological examination of the parotid gland and re-evaluation of the RCC material was performed by an experienced pathologist who specialized in uropathology. The light microscopy of the RCC showed cells with clear cytoplasm surrounded by a distinct cell membrane interspersed with abundant, thin walled blood vessels. The tumor had a uniform pattern and showed well-differentiated, sheet-like and compact epithelial cells. No mitotic figures or necrosis were seen. The renal vessels at the hilum, renal capsule and perinephritic fat were free of tumor. The histological diagnosis was clear cell RCC, grade 2, with moderate differentiation (Fig. 3).

image

Figure 3. Sheet of cells with clear cytoplasm interspersed with abundant, thin-walled blood vessels in the right kidney tumor. HE × 25.

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Pathological examination of the parotid gland revealed a tumor partly separated from the parotid gland by an irregular fibrous tissue. The cells of the tumor with glycogen-rich cytoplasm stained positive for periodic acid-schiff (PAS). The glycogen was completely removed by diastase. Immunohistochemical studies showed tumor positivity for cytokeratin, vimentin and epitelial membrane antigen (EMA) antibodies. Immunoreactivity for EMA was partial. Carcinoembryonic antigen (CEA), smooth muscle actin and S-100 protein were not revealed by immunohistochemistry of the tumor tissue. The diagnosis was metastatic clear RCC (Fig. 4).

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Figure 4. Metastatic clear renal cell carcinoma of the parotid tumor showing clear cells and small vessels separated by irregular fibrous tissue from parotid gland. HE × 10.

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In the follow-up of the patient, one year after parotidectomy, the patient developed multiple RCC on the contralateral kidney and she underwent left radical nephrectomy during June 2002. She is currently on a dialysis program and has developed no additional metastasis for 18 months.

Discussion

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

Metastasis to the parotid gland is very uncommon and mostly originates from head and neck squamous cell carcinomas or melanomas of the skin;4 parotid metastasis from RCC is extremely rare. In a postmortem series of 1451 RCC, Saitoh et al. found ENT metastasis in 5% of cases but none had parotid metastasis.5 Kidneys receive approximately 25% of the circulating blood volume. There was no tumor invasion in the arteries, veins and lymphatic vessels in the parotid gland in the present case. However, RCC are hypervascular tumors associated with multiple arteriovenous shunts and metastasize to the parotid gland via the hematogeneous route.6

Parotid metastasis is usually the initial presenting symptom of the malignant kidney tumor, but may also be seen after the primary treatment for RCC.3 There are 11 such cases of parotid metastasis in the published literature.3 In this situation, most patients present with multiple metastasis and solitary parotid metastasis after tumor nephrectomy is extremely rare.3 The time for parotid metastasis ranges from several months to years after primary treatment.3 To our knowledge, the longest time interval is 9 years with only 1 case reported in the literature.7

The common presenting symptom in these cases is usually a painless parotid mass as in the present case, but in some patients, pain and tenderness may also be found. Fine needle aspiration biopsy and immunohistochemical studies are helpful for evaluating parotid mass.8,9

One of the most important issues is to differentiate other parotid neoplasms from metastatic renal cell carcinoma. The use of PAS and enzymes, such as diastase, are helpful in distinguishing primary parotid tumors, such as acinic cell and mucoepidermoid carcinoma (Ca), from RCC.9 Renal cell carcinoma contains glycogen, making it PAS-positive and diastase-negative.9 On the other hand, acinic cell Ca and mucoepidermoid Ca are revealed as PAS-positive and contain diastase resistant material.9 Additionally, RCC shows immunohistochemically positive staining with keratin and vimentin and CEA negativity, supporting the diagnosis of metastatic RCC.10 In the present case, the tumor cells were PAS-positive and a diastase-negative reaction occured. Immunohistochemically, tumor cells showed keratin and vimentin positivity and CEA negativity. All of these findings helped to confirm the diagnosis of metastatic RCC.

Solitary parotid metastasis from RCC therapy is superficial parotidectomy with the preservation of the facial nerve.3 It is well known that solitary metastasis and a greater interval between the primary treatment to the appearance of the metastasis are favorable prognostic factors in RCC.1 Interestingly, the patient developed contralateral multiple RCC one year after parotidectomy and had undergone a left radical nephrectomy. She had no additional metastasis after 18 months of follow-up. It is not easy to estimate the prognosis in these patients as there are few cases in the published literature.

References

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