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Metastatic renal cell carcinoma presenting as a parotid tumor
Metastatic renal cell carcinoma presenting as a parotid tumor Beatriz Patin~o Seijas, MD,a Fernanda Lorenzo Franco, MD,b Roberto Martı´n Sastre, MD,b ´ lvarez Garcı´a, MD,c and Jose´ Luis Lo´pez-Cedru´n Cembranos, MD,d La Corun~a, Spain Augusto A JUAN CANALEJO HOSPITAL
Metastases of malignancies to the parotid region are relatively infrequent (21%-42% of all malignant tumors1), but metastases of infraclavicular origin are infrequent (0.16%-4%1,2). From 1986 to 1998, only 17 cases of parotid metastases of renal clear cell carcinoma were documented in the literature reviewed. In this paper we report a case of a patient with a parotid tumor which was the first manifestation of distant disease. It was only once the tumor was surgically removed that the histopathology allowed the diagnosis of the primary tumor; namely a renal clear cell adenocarcinoma. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005;99:554-7)
CASE REPORT A 67-year-old man referred by his general practitioner for diagnosis of a mass in the left parotid region first noted 4 months previously. On palpation a painless mass of about 2 cm was found. It was not adherent to the skin and was mobile in respect to the superficial and deep tissues. The facial nerve was not involved. A fine-needle aspiration was performed. Cytology revealed no evidence of malignancy, with ductal and acinic cells in discreet amount without significant morphologic deviations. CT scan showed a 3 3 2.5 cm solid poorly defined mass in the superficial lobe of the left parotid gland, intensely and homogeneously enhanced with contrast (Fig 1). Superficial parotidectomy was performed, preserving the facial nerve. Histology disclosed a nonencapsulated well defined tumor, though it had some infiltrating areas. The mass was totally composed of cells with round central nucleus and abundant clear cytoplasm (Fig 2). Pleomorphism was limited. Areas without clear cells were not observed. Tumoral cells were negative for glycogen and mucin. No mitoses were found. Immunohistochemical stains revealed that the tumor cells were positive for low-molecular-weight cytokeratins (CAM 5.2 and AE3) and for vimentin, and were negative for S-100 protein, CK7, CK20, and epithelial membrane antigen (EMA). Initially, the case was oriented as a clear cell acinic cell carcinoma. A posterior inmunohistochemical study revealed that the tumoral cells were positive for CD10 (Figs 3 and 4), which suggested the possibility of metastasis of a renal
a
Resident, Department of Maxillofacial Surgery. Consultant maxillofacial surgeon, Department of Maxillofacial Surgery. c Consultant pathologist, Department of Pathology. d Chief of Department, Department of Maxillofacial Surgery. Received for publication Mar 29, 2004; returned for revision Jun 24, 2004; accepted for publication Aug 10, 2004. Available online 8 December 2004. 1079-2104/$ - see front matter Ó 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.tripleo.2004.08.007 b
554
clear cell adenocarcinoma. Abdominal CT (Fig 5) disclosed a right renal tumor and left adrenal mass; surgery was performed (left adrenalectomy and right radical nephrectomy). The histologic report revealed a renal clear cell adenocarcinoma and confirmed the renal tumor as the primary neoplasm (Fig 6). Unfortunately, even though there was not local recurrence in the parotid region 2 years after surgery, an abdominal CT disclosed metastatic disease in both lungs, right adrenal gland and para-aortic retroperitoneal adenopathies. The patient died a few months after that finding.
DISCUSSION Malignant neoplasms account for 15%-35% of all parotid gland tumors; 21%-42% of those correspond to metastatic processes.1 Most metastatic tumors of the salivary glands proceed from lesions of the head and neck and consist of melanomas in 45% of cases and squamous cell carcinomas of the skin in 37%. Only a small percentage arise from distant sites such as the lung, breast, kidney, gastrointestinal tract, and prostate. In 1998, seventeen cases of renal clear cell adenocarcinoma metastasis to the parotid have been documented; of these, only 7 cases presented with solitary gland involvement.1 Tumors composed exclusively of or predominantly of clear cells are also rare in that location, representing only 1% to 2% of all tumors in the salivary glands, jaws, and oral mucosa.3 Clear cells in these lesions most often result from artifacts of fixation, but in some instances they may be a reflection of peculiar functional states of the tumor cells. A scarcity of organelles, glycogen storage, and accumulation of mucins, lipids, tonofilaments, and immature zymogen granules also may account for this appearance.3 When clear cells predominate, a definitive diagnosis may be problematic because many of these tumors will share histologic features. Indeed, the segregation of benign from malignant neoplasia may be obfuscatory.4 The histopathologic finding of a malignant
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Patin~o Seijas et al 555
Fig 1. CT of the parotid left gland, showing a 3 3 2.5 cm solid poorly defined mass in the superficial lobe.
Fig 3. (3100) After immunohistochemical study, the tumor cells stain with CD10 marker.
Fig 2. (HE) The mass was totally composed of cells with round central nucleus and abundant clear cytoplasm.
Fig 4. (3300) CD10 immunoreactivity.
clear cell tumor in a parotidectomy surgical specimen involves the necessity of differential diagnosis between clear cell primary parotid tumors and the uncommon metastases. Carcinomas from the kidney, liver, large bowel, prostate, and thyroid are known to have the potential for clear cell differentiation and all of them are able to metastasize to the maxillofacial area with renal cell carcinoma doing so most frequently.3 Renal cell carcinoma usually occurs in the sixth or seventh decade of life and is 3 times more common in men than in women.8 The clear cell is the most common tumor cell type. The typical histologic features of the renal cell carcinoma of clear cell type consist of highly vascularized sheets, cords, and tubular aggregates of tumor cells with abundant clear cytoplasm. Most patients have gross hematuria, while other common symptoms include costovertebral pain and a palpable mass in the flank, but some tumors may remain asymptomatic until they become quite large. Constitutional symptoms including fever, malaise, weakness, and weight loss can also be present. Metastases can involve almost any
extrarenal site. The long bones and lungs are most commonly involved. The thyroid gland is the most frequently described site of head and neck metastases from this tumor. According to different series, renal clear cell adenocarcinoma rarely metastasizes in the maxillofacial area: between 5%5 and 15%.6-8 Metastases to the parotid area even more uncommon (0.5%2). Some tumors may remain asymptomatic until they become quite large,8 so that symptoms derived from these metastases can be the first ones to appear. Classically, the differential diagnosis of clear cell tumors in the parotid area includes mainly clear cell variants of primary tumors such as clear cell myoepithelial carcinoma, clear cell epithelial-myoepithelial carcinoma, clear cell acinic cell carcinoma, clear cell adenocarcinoma of salivary glands and hyalinizing clear cell carcinoma. Also clear cell mucoepidermoid carcinoma, clear cell oncocytoma and clear cell odontogenic tumors need to be ruled out.3 Immunohistochemical evaluation may be useful in distinguish these tumors, but
556 Patin~o Seijas et al
OOOOE May 2005
Fig 5. A contrast CT of the abdomen showing a large mass replacing the majority of the right kidney.
Fig 6. Histological report of the renal tumor: a renal clear cell adenocarcinoma that confirmed the renal tumor as the primary neoplasm.
its sensibility and specificity is occasionally not enough to confirm the diagnosis. Clear cell myoepithelial carcinoma and clear cell epithelial-myoepithelial carcinoma are positive for myoepithelial stains,9 such as S-100 protein and actin. Myoepithelial carcinoma expresses also cytokeratins and vimentin. Epithelial-myoepithelial carcinoma presents a biphasic appearance3: Duct-like structures are lined by cuboidal eosinophilic epithelial cells that abut lumina; these are surrounded by rounded or fusiform clear cells which mantle a prominent basal lamina. Immunohistochemical studies have shown an epithelial origin for the inner cell layer, which displays cytokeratins and EMA immunoreactivity. The clear cell component, on the other hand, shows a typical myoepithelial phenotype: S-100 protein, a-isoform actin, and vimentin. Immunohistochemically, acinic cell carcinomas show varied staining reactions depending on the cell type and differentiation of the tumor. Positivity for S-100 protein but also for amylase, cytokeratins, and vimentin has been reported.3 Acinic cell carcinomas are generally low-grade tumors with a good prognosis. Five year survival rates of 80%-85% are generally reported. Mucoepidermoid carcinoma is the most common malignancy of salivary glands. Selected tumors that are almost exclusively composed of clear elements have been reported.3 These cells may contain PAS-positive, diastase-sensitive droplets of glycogen together with mucopolysaccharides. They also stain for Alcian blue. Accurate differential diagnosis with other clear salivary gland tumors needs an exhaustive search for Alcian bluee and PAS-positive mucin-producing cells. Several ultrastructural studies about oncocytomas have shown that their characteristic cytoplasmic granularity is due to large numbers of mitochondria. The tumor cells also contain glycogen, but lack acid
mucopolysaccharides. Immunohistochemical stains for S-100 protein and muscle-specific actin are negative, and those for cytokeratin are positive. Clear cell carcinoma of salivary glands is a relatively rare tumor (approximately 1% of all salivary gland tumors). This low-grade malignant tumor of putative duct cell origin is composed exclusively of a monomorphic population of undifferentiated cells that have optically clear cytoplasm but lack features that would allocate them in any of the specific categories. Some authors consider that definite differentiation between this tumor and metastatic renal clear cell adenocarcinoma in the salivary gland is often impossible by pathologic studies alone, and requires clinical evaluation to rule out a primary renal tumor.9 Clear cell carcinoma of salivary glands usually express epithelial markers (cytokeratins, EMA, and carcinoembryonic antigen (CEA)) but lack expression of myoepithelial markers (S-100 protein, actin, vimentin, and glial fibrillary acid protein). Hyalinizing clear cell carcinoma most frequently arises in females in minor salivary glands3 and it is composed of uniformly clear cells and others with weakly eosinophilic cytoplasm. The cytoplasm of the clear cells shows PAS-positive, diastase-sensitive glycogen granules but is devoid of mucin. Immunohistochemistry shows the expression of epithelial markers (cytokeratin, EMA, and, occasionally, CEA) but an absence of myoepithelial determinants (S-100, actin, and vimentin). This tumor also presents an hyaline fibrous stroma that may undergo myxoid or hyaline degeneration. The stroma may hence resemble amyloid, but it is Congo red negative. Immunohistochemical staining in renal clear cell carcinoma shows complete negativity for high-molecular-weight cytokeratin and weak and moderate patchy staining for low-molecular-weight cytokeratin (CAM 5.2) in more than 80% of the cases. It also stains strongly
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for EMA and vimentin and it is negative for actin, S-100, glial fibrillary acid protein, and CEA.9 Recently, CD10 immunoreactivity was observed in 90%10 to 94%11 of the cases of renal clear cell carcinoma, which permits more specificity in the histopathologic diagnosis. CD10 is a cell membraneeassociated neutral endopeptidase, also known as enkephalinase, CALLA, and EC3.3.24.11, that plays a physiological role in degrading biologically active peptides, including those implicated in autocrine growth stimulation of certain cancers.10 The average prognosis for surgically resected renal clear cell carcinoma is a 50% 5-year survival rate. However, patients with stage IV disease with distant metastases generally have less than 5% 5-year survival, irrespective of the treatment employed. On the other hand, the prognosis for primary parotid tumors is considerably better. Renal primary neoplasm needs to be resected as well, which makes the histologic diagnosis of this entity indispensable.
CONCLUSION It is generally considered that definite differentiation between clear cell primary tumors of parotid gland and metastatic clear cell renal adenocarcinoma in the same location is quite difficult. The importance of the correct diagnosis lies in the possibility of localizing the primary tumor and treating it adequately. Although metastases of renal tumors to the parotid region are rare, when histopathologic study demonstrates a clear cell epithelial tumor in this area, renal clear cell adenocarcinoma should come to mind as one of the main possibilities of origin.
Patin~o Seijas et al 557 REFERENCES 1. Vara A, Madrigal B, Pe´rez del Rı´o MJ, Dı´az A, Mateos A, Sales C. Parotid metastasis from renal clear cell adenocarcinoma. Urol Int 1998;61:196-8. 2. Pisani P, Angeli G, Krangli M, Pia F. Renal carcinoma metastasis to the parotid gland. J Laryngol Otol 1990;104:352-4. 3. Maoirano E, Altini M, Fabia G. Clear cell tumors of the salivary glands, jaws and oral mucosa. Semin Diagn Pathol 1997;14: 203-12. 4. Eversole LR. On the differential diagnosis of clear cell tumours of the head and neck. Oral Oncol Eur J Cancer 1993; 29B:173-9. 5. Saitoh H. Distant metastasis of renal adenocarcinoma. Cancer 1981;48:1487-91. 6. Som PM, Norton KI, Shugar JM, Reede DL, Norton L, Biller HF, et al. Metastatic hypernephroma to the head and neck. AJNR Am J Neuroradiol 1987;8:1103-6. 7. Madison JF, Frierson HF Jr. Pathologic quiz case 2. Clear cell carcinoma, consistent with metastatic renal cell carcinom. Arch Otolaryngol Head Neck Surg 1988;114:570-3. 8. Boggess MA, Hester TO, Archer SM. Renal clear cell carcinoma appearing as a left neck mass. Ear Nose Throat J 1996; 75:620-2. 9. Rezende RB, Drachenberg CB, Kumar D, Blanchaert R, Ord RA, Ioffe OB, et al. Differential diagnosis between monomorphic clear cell adenocarcinoma of salivary glands and renal (clear) cell carcinoma. Am J Surg Pathol 1999;23:1532-8. 10. Yang B, Ali SZ, Rosenthal DL. CD10 facilitates the diagnosis of metastatic renal cell carcinoma from primary adrenal cortical neoplasma in adrenal fine-needle aspiration. Diagn Cytopathol 2002;27:149-52. 11. Avery AK, Beckstead J, Renshaw AA, Corless CL. Use of antibodies to RCC and CD10 in the differential diagnosis of renal neoplasms. Am J Surg Pathol 2000;24:203-10. Reprint requests: Beatriz Patin~o Seijas Juan Canalejo Hospital As Xubias de Arriba 84. Postal Code 15006 La Corun ~a, Spain [email protected]
Metastases of malignancies to the parotid region are relatively infrequent (21%-42% of all malignant tumors1), but metastases of infraclavicular origin are infrequent (0.16%-4%1,2). From 1986 to 1998, only 17 cases of parotid metastases of renal clear cell carcinoma were documented in the literature reviewed. In this paper we report a case of a patient with a parotid tumor which was the first manifestation of distant disease. It was only once the tumor was surgically removed that the histopathology allowed the diagnosis of the primary tumor; namely a renal clear cell adenocarcinoma. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005;99:554-7)
CASE REPORT A 67-year-old man referred by his general practitioner for diagnosis of a mass in the left parotid region first noted 4 months previously. On palpation a painless mass of about 2 cm was found. It was not adherent to the skin and was mobile in respect to the superficial and deep tissues. The facial nerve was not involved. A fine-needle aspiration was performed. Cytology revealed no evidence of malignancy, with ductal and acinic cells in discreet amount without significant morphologic deviations. CT scan showed a 3 3 2.5 cm solid poorly defined mass in the superficial lobe of the left parotid gland, intensely and homogeneously enhanced with contrast (Fig 1). Superficial parotidectomy was performed, preserving the facial nerve. Histology disclosed a nonencapsulated well defined tumor, though it had some infiltrating areas. The mass was totally composed of cells with round central nucleus and abundant clear cytoplasm (Fig 2). Pleomorphism was limited. Areas without clear cells were not observed. Tumoral cells were negative for glycogen and mucin. No mitoses were found. Immunohistochemical stains revealed that the tumor cells were positive for low-molecular-weight cytokeratins (CAM 5.2 and AE3) and for vimentin, and were negative for S-100 protein, CK7, CK20, and epithelial membrane antigen (EMA). Initially, the case was oriented as a clear cell acinic cell carcinoma. A posterior inmunohistochemical study revealed that the tumoral cells were positive for CD10 (Figs 3 and 4), which suggested the possibility of metastasis of a renal
a
Resident, Department of Maxillofacial Surgery. Consultant maxillofacial surgeon, Department of Maxillofacial Surgery. c Consultant pathologist, Department of Pathology. d Chief of Department, Department of Maxillofacial Surgery. Received for publication Mar 29, 2004; returned for revision Jun 24, 2004; accepted for publication Aug 10, 2004. Available online 8 December 2004. 1079-2104/$ - see front matter Ó 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.tripleo.2004.08.007 b
554
clear cell adenocarcinoma. Abdominal CT (Fig 5) disclosed a right renal tumor and left adrenal mass; surgery was performed (left adrenalectomy and right radical nephrectomy). The histologic report revealed a renal clear cell adenocarcinoma and confirmed the renal tumor as the primary neoplasm (Fig 6). Unfortunately, even though there was not local recurrence in the parotid region 2 years after surgery, an abdominal CT disclosed metastatic disease in both lungs, right adrenal gland and para-aortic retroperitoneal adenopathies. The patient died a few months after that finding.
DISCUSSION Malignant neoplasms account for 15%-35% of all parotid gland tumors; 21%-42% of those correspond to metastatic processes.1 Most metastatic tumors of the salivary glands proceed from lesions of the head and neck and consist of melanomas in 45% of cases and squamous cell carcinomas of the skin in 37%. Only a small percentage arise from distant sites such as the lung, breast, kidney, gastrointestinal tract, and prostate. In 1998, seventeen cases of renal clear cell adenocarcinoma metastasis to the parotid have been documented; of these, only 7 cases presented with solitary gland involvement.1 Tumors composed exclusively of or predominantly of clear cells are also rare in that location, representing only 1% to 2% of all tumors in the salivary glands, jaws, and oral mucosa.3 Clear cells in these lesions most often result from artifacts of fixation, but in some instances they may be a reflection of peculiar functional states of the tumor cells. A scarcity of organelles, glycogen storage, and accumulation of mucins, lipids, tonofilaments, and immature zymogen granules also may account for this appearance.3 When clear cells predominate, a definitive diagnosis may be problematic because many of these tumors will share histologic features. Indeed, the segregation of benign from malignant neoplasia may be obfuscatory.4 The histopathologic finding of a malignant
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Patin~o Seijas et al 555
Fig 1. CT of the parotid left gland, showing a 3 3 2.5 cm solid poorly defined mass in the superficial lobe.
Fig 3. (3100) After immunohistochemical study, the tumor cells stain with CD10 marker.
Fig 2. (HE) The mass was totally composed of cells with round central nucleus and abundant clear cytoplasm.
Fig 4. (3300) CD10 immunoreactivity.
clear cell tumor in a parotidectomy surgical specimen involves the necessity of differential diagnosis between clear cell primary parotid tumors and the uncommon metastases. Carcinomas from the kidney, liver, large bowel, prostate, and thyroid are known to have the potential for clear cell differentiation and all of them are able to metastasize to the maxillofacial area with renal cell carcinoma doing so most frequently.3 Renal cell carcinoma usually occurs in the sixth or seventh decade of life and is 3 times more common in men than in women.8 The clear cell is the most common tumor cell type. The typical histologic features of the renal cell carcinoma of clear cell type consist of highly vascularized sheets, cords, and tubular aggregates of tumor cells with abundant clear cytoplasm. Most patients have gross hematuria, while other common symptoms include costovertebral pain and a palpable mass in the flank, but some tumors may remain asymptomatic until they become quite large. Constitutional symptoms including fever, malaise, weakness, and weight loss can also be present. Metastases can involve almost any
extrarenal site. The long bones and lungs are most commonly involved. The thyroid gland is the most frequently described site of head and neck metastases from this tumor. According to different series, renal clear cell adenocarcinoma rarely metastasizes in the maxillofacial area: between 5%5 and 15%.6-8 Metastases to the parotid area even more uncommon (0.5%2). Some tumors may remain asymptomatic until they become quite large,8 so that symptoms derived from these metastases can be the first ones to appear. Classically, the differential diagnosis of clear cell tumors in the parotid area includes mainly clear cell variants of primary tumors such as clear cell myoepithelial carcinoma, clear cell epithelial-myoepithelial carcinoma, clear cell acinic cell carcinoma, clear cell adenocarcinoma of salivary glands and hyalinizing clear cell carcinoma. Also clear cell mucoepidermoid carcinoma, clear cell oncocytoma and clear cell odontogenic tumors need to be ruled out.3 Immunohistochemical evaluation may be useful in distinguish these tumors, but
556 Patin~o Seijas et al
OOOOE May 2005
Fig 5. A contrast CT of the abdomen showing a large mass replacing the majority of the right kidney.
Fig 6. Histological report of the renal tumor: a renal clear cell adenocarcinoma that confirmed the renal tumor as the primary neoplasm.
its sensibility and specificity is occasionally not enough to confirm the diagnosis. Clear cell myoepithelial carcinoma and clear cell epithelial-myoepithelial carcinoma are positive for myoepithelial stains,9 such as S-100 protein and actin. Myoepithelial carcinoma expresses also cytokeratins and vimentin. Epithelial-myoepithelial carcinoma presents a biphasic appearance3: Duct-like structures are lined by cuboidal eosinophilic epithelial cells that abut lumina; these are surrounded by rounded or fusiform clear cells which mantle a prominent basal lamina. Immunohistochemical studies have shown an epithelial origin for the inner cell layer, which displays cytokeratins and EMA immunoreactivity. The clear cell component, on the other hand, shows a typical myoepithelial phenotype: S-100 protein, a-isoform actin, and vimentin. Immunohistochemically, acinic cell carcinomas show varied staining reactions depending on the cell type and differentiation of the tumor. Positivity for S-100 protein but also for amylase, cytokeratins, and vimentin has been reported.3 Acinic cell carcinomas are generally low-grade tumors with a good prognosis. Five year survival rates of 80%-85% are generally reported. Mucoepidermoid carcinoma is the most common malignancy of salivary glands. Selected tumors that are almost exclusively composed of clear elements have been reported.3 These cells may contain PAS-positive, diastase-sensitive droplets of glycogen together with mucopolysaccharides. They also stain for Alcian blue. Accurate differential diagnosis with other clear salivary gland tumors needs an exhaustive search for Alcian bluee and PAS-positive mucin-producing cells. Several ultrastructural studies about oncocytomas have shown that their characteristic cytoplasmic granularity is due to large numbers of mitochondria. The tumor cells also contain glycogen, but lack acid
mucopolysaccharides. Immunohistochemical stains for S-100 protein and muscle-specific actin are negative, and those for cytokeratin are positive. Clear cell carcinoma of salivary glands is a relatively rare tumor (approximately 1% of all salivary gland tumors). This low-grade malignant tumor of putative duct cell origin is composed exclusively of a monomorphic population of undifferentiated cells that have optically clear cytoplasm but lack features that would allocate them in any of the specific categories. Some authors consider that definite differentiation between this tumor and metastatic renal clear cell adenocarcinoma in the salivary gland is often impossible by pathologic studies alone, and requires clinical evaluation to rule out a primary renal tumor.9 Clear cell carcinoma of salivary glands usually express epithelial markers (cytokeratins, EMA, and carcinoembryonic antigen (CEA)) but lack expression of myoepithelial markers (S-100 protein, actin, vimentin, and glial fibrillary acid protein). Hyalinizing clear cell carcinoma most frequently arises in females in minor salivary glands3 and it is composed of uniformly clear cells and others with weakly eosinophilic cytoplasm. The cytoplasm of the clear cells shows PAS-positive, diastase-sensitive glycogen granules but is devoid of mucin. Immunohistochemistry shows the expression of epithelial markers (cytokeratin, EMA, and, occasionally, CEA) but an absence of myoepithelial determinants (S-100, actin, and vimentin). This tumor also presents an hyaline fibrous stroma that may undergo myxoid or hyaline degeneration. The stroma may hence resemble amyloid, but it is Congo red negative. Immunohistochemical staining in renal clear cell carcinoma shows complete negativity for high-molecular-weight cytokeratin and weak and moderate patchy staining for low-molecular-weight cytokeratin (CAM 5.2) in more than 80% of the cases. It also stains strongly
OOOOE Volume 99, Number 5
for EMA and vimentin and it is negative for actin, S-100, glial fibrillary acid protein, and CEA.9 Recently, CD10 immunoreactivity was observed in 90%10 to 94%11 of the cases of renal clear cell carcinoma, which permits more specificity in the histopathologic diagnosis. CD10 is a cell membraneeassociated neutral endopeptidase, also known as enkephalinase, CALLA, and EC3.3.24.11, that plays a physiological role in degrading biologically active peptides, including those implicated in autocrine growth stimulation of certain cancers.10 The average prognosis for surgically resected renal clear cell carcinoma is a 50% 5-year survival rate. However, patients with stage IV disease with distant metastases generally have less than 5% 5-year survival, irrespective of the treatment employed. On the other hand, the prognosis for primary parotid tumors is considerably better. Renal primary neoplasm needs to be resected as well, which makes the histologic diagnosis of this entity indispensable.
CONCLUSION It is generally considered that definite differentiation between clear cell primary tumors of parotid gland and metastatic clear cell renal adenocarcinoma in the same location is quite difficult. The importance of the correct diagnosis lies in the possibility of localizing the primary tumor and treating it adequately. Although metastases of renal tumors to the parotid region are rare, when histopathologic study demonstrates a clear cell epithelial tumor in this area, renal clear cell adenocarcinoma should come to mind as one of the main possibilities of origin.
Patin~o Seijas et al 557 REFERENCES 1. Vara A, Madrigal B, Pe´rez del Rı´o MJ, Dı´az A, Mateos A, Sales C. Parotid metastasis from renal clear cell adenocarcinoma. Urol Int 1998;61:196-8. 2. Pisani P, Angeli G, Krangli M, Pia F. Renal carcinoma metastasis to the parotid gland. J Laryngol Otol 1990;104:352-4. 3. Maoirano E, Altini M, Fabia G. Clear cell tumors of the salivary glands, jaws and oral mucosa. Semin Diagn Pathol 1997;14: 203-12. 4. Eversole LR. On the differential diagnosis of clear cell tumours of the head and neck. Oral Oncol Eur J Cancer 1993; 29B:173-9. 5. Saitoh H. Distant metastasis of renal adenocarcinoma. Cancer 1981;48:1487-91. 6. Som PM, Norton KI, Shugar JM, Reede DL, Norton L, Biller HF, et al. Metastatic hypernephroma to the head and neck. AJNR Am J Neuroradiol 1987;8:1103-6. 7. Madison JF, Frierson HF Jr. Pathologic quiz case 2. Clear cell carcinoma, consistent with metastatic renal cell carcinom. Arch Otolaryngol Head Neck Surg 1988;114:570-3. 8. Boggess MA, Hester TO, Archer SM. Renal clear cell carcinoma appearing as a left neck mass. Ear Nose Throat J 1996; 75:620-2. 9. Rezende RB, Drachenberg CB, Kumar D, Blanchaert R, Ord RA, Ioffe OB, et al. Differential diagnosis between monomorphic clear cell adenocarcinoma of salivary glands and renal (clear) cell carcinoma. Am J Surg Pathol 1999;23:1532-8. 10. Yang B, Ali SZ, Rosenthal DL. CD10 facilitates the diagnosis of metastatic renal cell carcinoma from primary adrenal cortical neoplasma in adrenal fine-needle aspiration. Diagn Cytopathol 2002;27:149-52. 11. Avery AK, Beckstead J, Renshaw AA, Corless CL. Use of antibodies to RCC and CD10 in the differential diagnosis of renal neoplasms. Am J Surg Pathol 2000;24:203-10. Reprint requests: Beatriz Patin~o Seijas Juan Canalejo Hospital As Xubias de Arriba 84. Postal Code 15006 La Corun ~a, Spain [email protected]