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Year : 2014 | Volume : 2 | Issue : 1 | Page : 45 - 46  


Case Reports
Axillary schwannoma with extensive cystic change: Misdiagnosis on Cytology

Sudhir Kumar Vujhini1, Kandukuri Mahesh Kumar2, Indira Velagandla3, Ranga Reddy4, Divyagna Thatikonda5

1Associate Professor, 2Assistant Professor, 3Professor and Head of Dept of Pathology, 4Professor and Head of General Surgery5, Asst. Professor of Pathology, MRIMS, Suraram, Hyderabad, Andhra Pradesh.

Abstract:

Schwannomas are benign tumors of peripheral and cranial nerves. They occur frequently in head and neck region. Schwannomas occurring in the axillary region is extremely rare. Cystic change is common in longstanding cases and in such cases aspiration may yield only macrophages leading to misdiagnosis of a case. We report one such case of solitary axillary schwannoma with extensive cystic degeneration, which was misdiagnosed on cytology, later confirmed by histological examination.

Keywords: - Schwannoma, Cystic change, Cytology

Corresponding Author: Dr. Sudhir Kumar Vujhini Associate Professor, Department of pathology, Mrims, Suraram , hyderabad-500 055. Email: vujhini07@yahoo.com

 

Introduction:

Axillary region is a source of swelling of wide range of pathological lesions. Fine Needle Aspiration Cytology (FNAC) is commonly advised as a first line of investigation for the diagnosis in many centers. Schwannomas are benign slow growing, solitary, well defined lesions arising from the Schwann cells and not incorporating nerve root. About 25 % of Schwannomas occur in the head and neck regions. [1] Most Schwannomas are usually 2-4 cm and are asymptomatic. Schwannomas arising from brachial plexus in the axillary region are uncommon. Degenerative changes such as hemorrhage, calcification, and fibrosis are commonly seen in the Schwannomas, but cystic changes are rare.

Despite extensive search in the literature, axillary Schwannomas with cystic change are extremely rare. We report here one such case misdiagnosed on cytology and confirmed with histological examination.

Case Report:

A 40 year old female presented to surgical out-patient department with complaint of swelling in the right axillary region since 2 years. Swelling gradually increased in size. There was no history of pain, trauma or other symptoms of systemic illness. Clinical examination revealed 5 x 4 cm oval mobile mass in the right axilla. Ultrasonology revealed presence of multiloculated cystic mass measuring 5.6 x 4.6 cm in the right axilla with a provisional diagnosis of hydatid cyst.

FNAC from the mass yielded 5 ml straw colored fluid. Smears show occasional macrophages in a proteinaceous background. The cytological diagnosis of benign cystic lesion was made without ruling out the possibility of sonological diagnosis of hydatid cyst.

The patient underwent surgery and excised mass was sent for Histopathological examination.

Gross examination revealed a mass lesion measuring 6 x 5 x 4.8 cm, external surface was smooth. Cut section revealed solid and multiple cystic areas filled partially with sticky material. Inner lining of the cyst wall was smooth.

Histological examination revealed Hypercellular and Hypocellular areas. Hypercellular (Antoni A) areas show spindle shaped cells with wavy nuclei arranged in fascicles with focal palisading of the nuclei and “Verocay bodies”. Hypocellular (Antoni B) areas show loose myxoid stroma. Considering the gross and microscopic features, a final diagnosis of Cystic Schwannoma was made.

Discussion:

Schwannomas are benign slow growing, solitary, well defined lesions arising from the Schwann cells and not incorporating nerve root. Extra cranial Schwannomas present as solitary mass anywhere in the body. The common sites include head and neck, flexor surfaces of upper and lower extremities, the posterior mediastinum in the thorax and the trunk, but localization in the axilla is very unusual. Schwannoma was first reported by Verocay in 1910.[2]Ancient schwannoma was initially mentioned by Ackerman and Taylor as a degenerative change occurring in a long standing schwannoma, was characterized by nuclear hyperchromasia, mild nuclear pleomorphism, stromal edema, fibrosis and xanthomatous changes leading to a misdiagnosis of malignancy in the aspirates.[3]The pre-operative diagnosis of cystic Schwannomas is extremely difficult because of the rarity of the lesion, with some potential contribution from the instability of the FNAC technique. In such cases FNAC aspirates hypocellular fluid from the center of the mass instead of material from the solid areas. Cytologically cystic Schwannomas may show amorphous acellular debris, lymphocytes, cyst macrophages and RBC’s which is insufficient of definitive diagnosis. [4]

Consequently, even though individual spindle cells, histiocytes, lymphocytes or fibrosis are present in the aspirated fluid, the characteristic cellular architecture of schwannoma may not be identifiable. Hence FNAC is not helpful in achieving pre-operative diagnosis in cystic lesions (Schwannomas), although the contribution of FNAC may increase when performed from solid areas under ultrasound guidance. [4]

Grossly, Schwannomas are solitary, well circumscribed, firm, smooth surfaced tumor, extra cranial Schwannomas manifests with secondary degenerative changes due to long duration. Schwannomas may demonstrate biphasic pattern with compact areas of high cellularity (Antoni A) and hypocellular myxoid areas with microcystic spaces (Antoni B). Long standing tumors may develop degenerative changes such as hemorrhage, calcification, fibrosis and cystic changes. [5] Degeneration is due to central tumor necrosis as the schwannoma grows to a size beyond the capacity of its blood supply. The tumor may be infiltrated with hemosiderin laden macrophages.

Axillary Schwannomas reported by Nikumbh et al, did not show cystic degeneration. [6] Axillary Schwannomas reported by Chen et al & Jadhav et al show cystic degeneration as in our present case. [6]

The differential diagnoses of such cystic lesions in the axilla include cystic schwannoma, ganglioma and lymphangioma. Histological examination along with gross findings will usually confirm the diagnosis as in our case. Immunohistochemistry of the Schwannoma show S-100 Positivity and Ki-67 Negativity.

To conclude schwannoma with extensive cystic degeneration should be considered on rare differential diagnosis of cystic lesions of the axilla. The histopathological examination remains the mainstay of differentiation as radio-imaging and FNAC features can be distinguishable.

References:

  1. Somayaji KSG, Rajeshwari A, Gangadhara KS. Schwannoma of the brachial plexus presenting as a cystic swelling. Indian J Otolaryngol Head Neck Surg 2004;56(3):228-30.
  2. Verocay J. Zur kenntnis der neurofibrome. Beitr Pathol Anat. 1910;48:1–69.
  3. Ackerman LV, Taylor FH. Neurogenous tumors within the thorax; A clinicopathological evaluation of forty-eight cases. Cancer 1951;4(4):669–91.
  4. Satarkar RN, Kolte SS, Vujhini SK. Cystic schwannoma in neck: fallacious diagnosis arrived on fine needle aspiration cytology. Diagn Cytopathol2011(11);39:866–7.
  5. Jaiswal A, Shetty AP, Rajasekaran S. Giant cystic intradural schwannoma in the lumbosacral region: A case report. J Orthop Surg (Hong Kong) 2008;16(1):102–6. 
  6. Jadhav CR, Angeline NR, Kumar B, Bhat RV, Balachandran G. Axillary schwannoma with extensive cystic degeneration. J Lab Physicians 2013;5(1):60-2.

Figure 1 showing oval mass (left) and cut-section with cystic spaces (right).

Figure 2 showing macrophages (Arrow) over a eosinophilic background. Inset shows “Verocay bodies” (Arrow) histologically.