Journal of Cytology
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Year : 2012  |  Volume : 29  |  Issue : 4  |  Page : 258-260
Solitary intramammary schwannoma mimicking phylloides tumor: Cytological clues in the diagnosis

Department of Pathology, ESIC Medical College and PGIMSR, Rajajinagar, Bangalore, Karnataka, India

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Date of Web Publication28-Nov-2012


A 30-year-old woman presented with a huge exophytic lobulated mass in the right breast, clinically and radiologically resembling phylloides tumor. Fine needle aspiration cytology smears showed clusters and singly scattered spindle cells along with structures reminiscent of verocay bodies. However, the epithelial elements were absent. A cytological diagnosis of benign mesenchymal spindle cell lesion, suggestive of schwannoma was rendered. Subsequent histopathological examination and strong S-100 positivity of tumor cells on immunohistochemistry confirmed the diagnosis.Breast is an uncommon location for benign schwannoma. The present case describes the unusual clinical picture, highlights cytological features and discusses the differential diagnoses of schwannoma from other benign spindle cells lesions of the breast on cytology smears.

Keywords: Breast; cytology; phylloides; schwannoma

How to cite this article:
Thejaswini M U, Padmaja K P, Srinivasamurthy V, Rao M S. Solitary intramammary schwannoma mimicking phylloides tumor: Cytological clues in the diagnosis. J Cytol 2012;29:258-60

How to cite this URL:
Thejaswini M U, Padmaja K P, Srinivasamurthy V, Rao M S. Solitary intramammary schwannoma mimicking phylloides tumor: Cytological clues in the diagnosis. J Cytol [serial online] 2012 [cited 2020 Oct 21];29:258-60. Available from:

   Introduction Top

Schwannoma (neurilemmoma) is a slow growing benign tumor arising from the nerve sheath of peripheral, cranial, and autonomous nerves. The tumor commonly occurs in head, neck, and flexor aspect of upper and lower extremities. Breast is an extremely rare location of this tumor, with only twenty three proven cases reported in the English literature. [1] We are herewith reporting an unusual case of schwannoma presenting as a massive exophytic breast lump, clinically mimicking phylloides tumor.

   Case Report Top

A 30-year-old lady presented to the surgical outpatient department with complaints of a slow growing painless lump in right breast of ten years duration. On examination, a huge exophytic, firm, non-tender mass, measuring about 15 cm × 12 cm was seen occupying the upper inner quadrant of right breast [Figure 1]a. However, there were no skin changes or axillary lymphadenopathy. A clinical diagnosis of phylloides tumor was made and the patient was subjected to fine needle aspiration cytology study. A 21 gauge needle was used and aspiration was performed from multiple sites. The smears were stained with hematoxylin and eosin and examined. The smears were cellular, composed of spindle shaped cells in clusters and singles, with scant cytoplasm, elongated vesicular, mildly pleomorphic nuclei; the background showed myxoid material [Figure 1]b. Ductal epithelial elements were characteristically absent. Occasional presence of structures resembling verocay bodies with nuclear palisades, separated by fibrillar material was observed [Figure 1]c. A cytological diagnosis of benign spindle cell tumor, favoring schwannoma was made. A differential diagnosis of phylloides tumor was also given because of the site, clinical features and the possibility of unsampled epithelial elements in a stroma predominant phylloides. The patient underwent lumpectomy.

The excised specimen was a skin covered lobulated mass measuring 15 cm × 11 cm × 6 cm with a solid, grey-white, and fleshy cut surface. Microscopic examination showed an encapsulated, predominantly cellular tumor composed of spindle shaped cells arranged in interlacing fascicles and whorls. Focal areas showed palisading of nuclei with intervening fibrillary cytoplasm resulting in verocay body formation [Figure 1]d. Hypocellular myxoid areas with dilated blood vessels were seen merging with the cellular areas imperceptibly. Epithelial elements were not seen within the lesion, even after extensive sampling. Immunohistochemical staining with S-100 protein yielded strong and diffuse positivity of the tumor cells and the epithelial markers such as cytokeratin and EMA were negative. A final diagnosis of intramammary schwannoma was made.
Figure 1: (a) Huge exophytic mass occupying the upper inner quadrant of right breast; (b) Clusters of spindle cells in a myxoid background (H and E, ×100); (c) Cytology smears with structures resembling verocay body (H and E, × 400); (d) Histopathology section showing a verocay body (H and E, × 400)

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   Discussion Top

Schwannoma is a benign tumor of peripheral nerve sheath origin which occurs most often as a solitary lesion. [2] It can rarely be multiple or observed in the context of Von-Recklinghausen's disease. Head, neck, flexor aspects of extremities, trunk, deeper soft tissues of mediastinum, and retroperitoneum are the common sites for schwannoma. Its occurrence in the breast is very rare, with very few reported cases in the English literature. [3]

The patients are usually between 18 years to 50 years of age. About 90% of schwannomas are sporadic, 3% occur in patients with neurofibromatosis-2, 2% in those with schwannomatosis and 5% in patients with multiple meningiomas with or without neurofibromatosis-2. [1]

Pain and neurological symptoms are uncommon unless the tumor becomes large. The usual size of the tumor ranges from 7 mm to 7 cm. Only one case with clinical presentation as an exophytic mass with skin invasion, mimicking breast carcinoma has been reported. [4] Ours is the second case of exophytic presentation with even larger measurements, but lacking skin invasion.

Schwannoma arising in the breast parenchyma appears as a well circumscribed equal dense nodule on mammography and as a well demarcated hypoechoic mass with or without cystic change on ultrasound, thereby mimicking a fibroadenoma or phylloides tumor. [2],[5] Often the lesion may simulate a malignant neoplasm on mammography. [6] Fine needle aspiration of schwannoma may trigger a sharp pain radiating along the nerves. Amount of material obtained may vary from case to case. If Antoni A areas are sampled, tissue fragments of cohesive spindle cells with indistinct cytoplasmic margins are seen. Verocay bodies are rarely encountered on cytology and if present, appear as compact rows of aligned nuclei separated by fibrillar material. [7] Samples from Antoni B areas yield paucicellular smears composed of dispersed cells in a myxoid background.

Cytologically, intramammary schwannoma is differentiated from phylloides tumor by the presence of sheets of ductal epithelial cells in the latter. Other mesenchymal neoplasms such as smooth muscle and fibromatous tumors also show spindle cells in palisading pattern. Hence, cytological diagnosis of schwannoma is specific only in the presence of verocay bodies. [8] Histopathological examination, supplemented by positive staining of tumor cells for S-100 protein on immunohistochemistry confirms the diagnosis of intramammary schwannoma.

In the breast, pre-operative differential diagnosis of schwannoma with myoepithelioma poses a challenge as both contain spindle cells in palisades and stain positive for S100 protein on immunocytochemistry. [9],[10] Presence of structures reminiscent of verocay bodies helps in the diagnosis of schwannoma.

Marked nuclear atypia, cyst macrophages, calcific deposits, and hyalinized fibrous fragments may be seen in cytology smears of an ancient schwannoma as a result of degenerative changes and hence should not be mistaken for malignancy. Schwannoma behaves in a benign fashion and recurrence after simple excision is rare.

   References Top

1.Weiss SW, Goldblum JR. Benign tumors of peripheral nerves. In: soft tissue tumors. 5th ed. China: Mosby Elsivier; 2008. p. 825-902.  Back to cited text no. 1
2.Bernardello F, Caneva A, Bresaola E, Mombello A, Zamboni G, Bonetti F, et al. Breast solitary schwannoma: fine needle aspiration biopsy and immunocytochemical analysis. Diagn Cytopathol 1994;10:221-3.  Back to cited text no. 2
3.Bellezza G, Lombardi T, Panzarola P, Sidoni A, Cavaliere A, Giansanti M. Schwannoma of the breast: a case report and review of the literature. Tumori 2007;93:308-11.  Back to cited text no. 3
4.Lee EK, Kook SH, Kwag HJ, Park YL, Bae WG. Schwannoma of the breast showing massive exophytic growth: a case report. Breast 2006;15:562-6.  Back to cited text no. 4
5.Uchida N, Yokoo H, Kuwano H. Schwannoma of the breast: report of a case. Surg Today 2005;35:238-42.  Back to cited text no. 5
6.Gultekin SH, Cody HS 3rd, Hoda SA. Schwannoma of the breast. South Med J 1996;89:238-9.  Back to cited text no. 6
7.Zbieranowski I, Bedard YC. Fine needle aspiration of schwannomas. Value of electron microscopy and immunohistochemistry in the preoperative diagnosis. Acta Cytol 1989;33:381-4.  Back to cited text no. 7
8.Neifer R, Nguyen GK. Aspiration cytology of solitary schwannoma. Acta Cytol 1985;29:12-4.  Back to cited text no. 8
9.Tavassoli FA. Myoepithelial lesions of the breast. Myoepitheliosis adenomyoepithelioma and myoepithelial carcinoma. Am J Surg Pathol 1991;15:554-68.  Back to cited text no. 9
10.Nguyen GK, Shnitka TK, Jewell LD. Aspiration biopsy cytology of mammary myoepithelioma. Diagn Cytopathol 1987;3:335-8.  Back to cited text no. 10

Correspondence Address:
M U Thejaswini
Department of Pathology, ESIC Medical College and PGIMSR, Rajajinagar, Bangalore, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0970-9371.103947

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