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Year : 2011  |  Volume : 54  |  Issue : 3  |  Page : 612-613
Solitary fibrous tumor presenting as a mass in the parotid gland

Department of Histopathology, Anand Diagnostic Laboratory, Bangalore, India

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Date of Web Publication20-Sep-2011

How to cite this article:
Iyengar JN, Atmaram M, Neeli D, Prasad S. Solitary fibrous tumor presenting as a mass in the parotid gland. Indian J Pathol Microbiol 2011;54:612-3

How to cite this URL:
Iyengar JN, Atmaram M, Neeli D, Prasad S. Solitary fibrous tumor presenting as a mass in the parotid gland. Indian J Pathol Microbiol [serial online] 2011 [cited 2022 Jan 18];54:612-3. Available from: https://www.ijpmonline.org/text.asp?2011/54/3/612/85114

A male aged 43 years presented with a slow-growing, painless swelling below and in front of the right ear lobe of 4 years duration. It measured 5 cm Χ 3 cm in size and the overlying skin was free and unremarkable. Fine needle aspiration cytology (FNAC) was reported elsewhere as pleomorphic adenoma, following which the parotid gland was excised.

The tissue was received in fragments, the largest measuring 5 cm Χ 3 cm Χ 2 cm. There was a fairly well-circumscribed, firm, whitish nodule measuring 4 cm Χ 3 cm ΧΧ 2 cm [Figure 1]. Sections stained with hematoxylin and eosin (H and E) showed a well-encapsulated neoplasm comprising of plump spindle cells haphazardly arranged in pattern-less sheets and admixed with bands of collagen. These cells had scant cytoplasm and regular nuclei. Mitotic activity was not increased. A mild infiltrate of lymphocytes and plasma cells was present. Intervening stroma showed branching blood vessels. Salivary ducts and acini were trapped within the tumor mass [Figure 2] and [Figure 3]. Immunohistochemical staining was performed with a provisional diagnosis of benign spindle cell neoplasm-probably solitary fibrous tumor. The results of immunohistochemistry (IHC) staining are given in [Table 1] and in [Figure 3].
Table 1: Immunohistochemical staining pattern of SFT of the parotid gland

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Figure 1: Fairly well-circumscribed mass on gross examination

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Figure 2: Tumor tissue with pushing margins, entrapping normal salivary epithelium (hematoxylin and eosin, x100)

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Figure 3: (a) Patternless arrangement of plump spindle cells with admixture of hyalinized collagen (hematoxylin and eosin [H and E], x200), (b) Plump spindle cells surrounding vascular spaces. Mild pleomorphism is seen but mitoses are not increased (H and E, x400), (c) Blood vessels and tumor cells staining positive with CD34 (IHC, x400), (d) Positive staining with CD99 within the tumor cells (IHC, x400)

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Solitary fibrous tumor was first reported by Klemperer and Rabin in 1931 [1] as a primary neoplasm of the pleura. Subsequent reports have recognized these tumors in a wide variety of locations, including the head and neck region. [2],[3] Major salivary glands are uncommon sites of occurrence of this neoplasm. The parotid is involved most often, and the sublingual salivary gland the least. [4] Involvement of the minor salivary glands in the oral cavity is also reported. The varied locations of origin reflect the mesenchymal histogenesis of this tumor.

The histological findings of a spindle cell proliferation with pushing margins, bland cytomorphology and admixture of variable amounts of collagen, proliferation of vascular spaces and presence of variable inflammatory cell infiltrate are quite characteristic. The immunestaining profile of solitary fibrous tumor (SFT) is quite characteristic, and all reported tumors are positive for vimentin and CD34 and negative for S-100 protein and CD 117. Positive staining with CD 34 is considered to be a marker for SFT, although it is also found in numerous other tumors. Strong expression of CD 99 and BCL2 in tumor cells supports the diagnosis of SFT. Lee et al. [5] have reported a tumor of the parotid as dermatofibrosarcoma protuberans with almost identical histological and immunostaining pattern. The presence of prominent storiform pattern and absence of prominent vascular proliferation helped differentiate this from SFT. The other tumor to be differentiated from SFT is hemangiopericytoma, which may demonstrate similar histological features, but the CD34 stain is less-frequently positive. Extrapulmonary SFT usually behaves in a benign fashion even in the histologically high-grade group, and complete surgical excision and long-term follow-up is advisable. An occasional case of SFT may have a malignant potential with local infiltration. [6]

To conclude, solitary fibrous tumor should be considered in the differential diagnosis of benign spindle cell tumors in various serosal and extraserosal locations. A combination of light microscopy and immunostaining helps to differentiate SFT from other tumors.

   References Top

1.Klemperer P, Rabin CB. Primary neoplasms of the pleura. Report of five cases. Arch Pathol 1931;11:385-412.  Back to cited text no. 1
2.Mukherjee B, Biswas J. Solitary fibrous tumor of the orbit. Indian J Pathol Microbiol 2008;51:453-5.  Back to cited text no. 2
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3.Alawi F, Stratton D, Freedman P. Solitary fibrous tumor of the oral soft tissue. Am J Surg Pathol 2001;25:900-10.  Back to cited text no. 3
4.Ferreiro JA, Nascimento JA. Solitary fibrous tumor of the major salivary glands. Histopathol 1996;28:261-4.  Back to cited text no. 4
5.Lee JO, Pi YD, Jo HD, Cho JK, Kim YS, Ro YJ. Dermatofibrosarcoma protuberans of the parotid gland-A Case Report. Korean J Pathol 2004;38:276-9.  Back to cited text no. 5
6.Ogawa I, Sato S, Kudo Y, Miyauchi M, Sugiyama M, Suei Y, et al. Solitary fibrous tumor with malignant potential arising in the sublingual gland. Pathol Int 2003;53:40-5.  Back to cited text no. 6

Correspondence Address:
Jayaram N Iyengar
Department of Histopathology, Anand Diagnostic Laboratory, No. 11, Blue Cross Chambers, Infantry Road Cross, Bangalore - 560 001, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0377-4929.85114

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  [Figure 1], [Figure 2], [Figure 3]

  [Table 1]

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1 Solitary fibrous tumor occurring in the parotid gland: a case report
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BMC Clinical Pathology. 2017; 17(1)
[Pubmed] | [DOI]


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