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Year : 2018  |  Volume : 61  |  Issue : 3  |  Page : 456-457
Metastasizing pleomorphic adenoma of parotid presenting as a huge renal mass

1 Department of Pathology, Government Medical College, Kottayam, Kerala, India
2 Department of Genitourinary Surgery, Government Medical College, Kottayam, Kerala, India

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Date of Web Publication13-Jul-2018

How to cite this article:
Mohan BP, Letha V, Pothen L, Bhat S. Metastasizing pleomorphic adenoma of parotid presenting as a huge renal mass. Indian J Pathol Microbiol 2018;61:456-7

How to cite this URL:
Mohan BP, Letha V, Pothen L, Bhat S. Metastasizing pleomorphic adenoma of parotid presenting as a huge renal mass. Indian J Pathol Microbiol [serial online] 2018 [cited 2021 Jul 23];61:456-7. Available from: https://www.ijpmonline.org/text.asp?2018/61/3/456/236592


Malignancy can arise in pleomorphic adenoma (PA) in the form of carcinoma ex PA (CEPA), carcinosarcoma, or metastasizing PA (MPA), with MPA accounting for 1% of malignant PA.[1] MPA is histologically benign and yet exhibits malignant behavior in the form of metastasis.

A 38-year-old male presented with a history of persistent loin pain and hematuria of 3-month duration. Ultrasonogram was suspicious of left renal hematoma. Contrast-enhanced computed tomography scan revealed a large enhancing lesion involving the left kidney, suggestive of malignancy [Figure 1]a. A left radical nephrectomy was done with a presumptive diagnosis of renal cell carcinoma.
Figure 1: (a) Contrast-enhanced computed tomography scan of abdomen showing a large enhancing lesion in the left kidney. (b) Radical nephrectomy specimen showing large, whitish, circumscribed, solid mass. (c) Renal tumor showing epithelial elements admixed with chondromyxoid stroma (H and E, ×100). (d) Pleomorphic adenoma in parotidectomy (H and E, ×40). (e) Immunostain CK-7 in epithelial component of renal tumor. (f) p63 in myoepithelial cells. (g) S-100 in myoepithelial cells and cells of chondromyxoid matrix. (h) Very low Ki-67 index

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Gross specimen showed a large whitish, circumscribed, solid mass in the kidney [Figure 1]b. Microscopic examination showed features of a benign biphasic neoplasm mimicking PA [Figure 1]c. Atypical mitosis, anaplasia, or lymphovascular emboli were not seen. Suspecting a nonrenal tumor, the patient's history was sought for which was significant for a parotidectomy 21 years before the current presentation. He had two recurrences at 8 years (2003) and 18 years (2013) following the initial surgery. On reviewing the slides of the parotidectomy specimen in 2013, histology was consistent with benign PA [Figure 1]d, and the excision was incomplete. Immunohistochemically, tumor cells expressed CK-7 (epithelial cells), p63 (myoepithelial cells), S-100 (myoepithelial cells and cells of chondromyxoid matrix) and very low MIB-1 (Ki-67)-labeling index (<1%) [Figure 1]e, [Figure 1]f, [Figure 1]g, [Figure 1]h. A final diagnosis of benign MPA was offered. The patient is on follow-up and asymptomatic.

MPA is a very rare tumor with only 84 cases described in English literature from 1942 to 2016, of which 8 are in the kidney.[2] There is a slight female predilection for MPA and the age at diagnosis ranges from 11 to 83 years (mean age at diagnosis 49.5 years) with the mean time interval between PA and MPA being 14.9 years (range 0–51 years).[2] Most common sites of metastasis are bone, lung, and lymph nodes.[2] The other less common sites of MPA are liver, thyroid, retroperitoneum, brain, and kidney.[3],[4] The sites of primary PA include parotid gland, submandibular gland, minor salivary glands (palate, nasal septum, and tongue), and lung.[5]

Histologically, the primary salivary gland tumor and metastases are composed of the typical mixture of benign-appearing epithelial and mesenchymal components of PA. Predictable morphological features of metastasizing tumors such as cellular atypia and mitosis are not known to occur in MPA. Immunohistochemically, our case showed p63 and S100 positivity suggestive of retained myoepithelial differentiation in the tumor cells, excluding CEPA.[3] Furthermore, CK-7 was strongly positive in epithelial elements and Ki-67 proliferation index was very low supporting benign histology.

The mortality rate of MPA is approximately 20%.[5] Development of metastasis within the first 10 years after the initial surgery and the presence of metastases in multiple sites are independent predictors of poor survival. In patients with recurrent PA, a careful screening of extraparotid symptoms is advisable due to the risk of malignant transformation.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Auclair PL, Langloss JM, Weiss SW, Corio RL. Sarcomas and sarcomatoid neoplasms of the major salivary gland regions. A clinicopathologic and immunohistochemical study of 67 cases and review of the literature. Cancer 1986;58:1305-15.  Back to cited text no. 1
Knight J, Ratnasingham K. Metastasising pleomorphic adenoma: Systematic review. Int J Surg 2015;19:137-45.  Back to cited text no. 2
Moonim M, Wiles K, Nasir A, Simo R. A unique case of benign pleomorphic adenoma metastasizing to the thyroid gland and liver. Case Report Clin Pathol 2015;2:74-9.  Back to cited text no. 3
Wenig BM, Hitchcock CL, Ellis GL, Gnepp DR. Metastasizing mixed tumor of salivary glands. A clinicopathologic and flow cytometric analysis. Am J Surg Pathol 1992;16:845-58.  Back to cited text no. 4
Manucha V, Ioffe OB. Metastasizing pleomorphic adenoma of the salivary gland. Arch Pathol Lab Med 2008;132:1445-7.  Back to cited text no. 5

Correspondence Address:
Bhavya P Mohan
Department of Pathology, Government Medical College, Kottayam, Kerala
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/IJPM.IJPM_111_17

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