Intrapulmonary Ancient Schwannoma: a Rare Tumour

Abstract

Schwannomas are benign encapsulated neoplasms which arise from Schwann cells of the neural sheath. Ancient schwannoma is a rare variant of schwannoma which is often misdiagnosed as a malignant neoplasm owing to degenerative changes. They are known to show degenerative nuclear atypia, cystic degeneration, hyalinization, myxoid change and haemorrhage. We present a rare case of an intrapulmonary ancient schwannoma in a 34-year-old female patient.

Introduction

Schwannomas are benign encapsulated neoplasms which arise from Schwann cells of the neural sheath. These cells are responsible for the formation of the myelin sheath in the peripheral nervous system [1]. The majority of these neural tumours (25–50%) are reported from the head and neck region [2].

Ancient schwannoma is a rare variant of schwannoma which is often misdiagnosed as a malignant neoplasm owing to degenerative changes. They are known to show degenerative nuclear atypia, cystic degeneration, hyalinization, myxoid change and haemorrhage [3]. While the lung is an uncommon site for the origin of neural tumours, only a single case of ancient schwannoma originating from lung parenchyma has been reported to date [4]. We present a rare case of an intrapulmonary ancient schwannoma in a 34-year-old female patient.

Case Report

A 34-year-old lady presented to the medicine outpatient department with complaints of dry cough and exertional dyspnoea. There was no history of smoking. Her routine blood investigations were within normal limits. Contrast-enhanced computed tomography of the chest exhibited a well-defined cystic lesion of size 65 × 58 mm involving the posterior segment of the right upper lobe with minimal posterior costal pleural thickening. There was no mediastinal lymphadenopathy or pleural effusion.

Intraoperatively, a 5 × 5 cm solid-cystic tumour was seen in the right upper lobe (Fig. 1). The tumour was excised and sent for histopathological examination.

Fig. 1.

Radiological and gross findings of intrapulmonary ancient schwannoma. a–b Computed tomography exhibiting a well-defined cystic lesion of size 65 × 58 mm involving the posterior segment of the right upper lobe. c–d Gross examination revealed a well-circumscribed encapsulated mass with cystic change

Gross examination showed a well-circumscribed grey-white globular mass with few cystic areas. Haematoxylin and eosin-stained sections revealed an encapsulated neoplasm with compact hypercellular Antoni A and myxoid hypocellular Antoni B areas. The hypercellular areas showed nuclear palisading and Verocay bodies. There were interspersed areas of hyalinization, myxoid and cystic change, haemorrhage and hemosiderin-laden macrophages. There were dilated haphazardly arranged vessels in the Antoni B areas. The tumour cells were predominantly wavy and elongated with tapered ends. However, focal areas showed degenerative atypia with enlarged hyperchromatic nuclei but without any abnormal mitosis.

On immunohistochemistry, the cells showed strong diffuse positivity for S-100. They were negative for SMA, CD34 and desmin. Ki-67 proliferation index was 4–5%. Thus, a final diagnosis of intrapulmonary ancient schwannoma was made (Fig. 2).

Fig. 2.

Histopathological and immunohistochemical findings of intrapulmonary ancient schwannoma. Haematoxylin and eosin-stained sections exhibiting Antoni A and Antoni B areas with nuclear palisading (a), cystic change (b), perivascular hyalinization (c), hemosiderin-laden macrophages (d) and degenerative nuclear atypia (e, f) [× 10, × 40]. Immunohistochemistry exhibiting diffuse positivity for S-100 (g, h) with a low Ki-67 (i) proliferation index

The patient is currently asymptomatic and under follow-up.

Discussion

Schwannoma is a benign neural tumour seen mostly in the head and neck region. Very few cases of intrapulmonary schwannomas have been reported to date [1, 5, 6]. They may be asymptomatic detected incidentally on a chest radiograph or present with chronic cough and dyspnoea. They account for around 0.2% of all lung neoplasms [2, 7].

Ancient schwannoma is a rare variant of schwannoma which exhibits degenerative atypia. It is commonly mistaken for malignancy owing to its degenerative changes. Previously, ancient schwannomas have been reported from the posterior mediastinum and pleura [2, 8–11].

However, only a single case of an intrapulmonary ancient schwannoma has been reported to date [4]. Domen et al. have previously reported a case of intrapulmonary cellular schwannoma where there was increased cellularity; however, no degenerative atypia was noted [12].

The previously reported case was a 56-year-old lady who presented with inspiratory dyspnoea, dry cough, vague right chest pain and right arm pain. Her chest radiograph exhibited a radiopacity involving the superior right lobe. Chest CT scanning revealed a large well-circumscribed heterogeneous tumour with focal calcifications, located in the posterior mediastinum [4]. The present case was a 34-year-old lady who presented with complaints of cough and exertional dyspnoea. Her lesion was located in the posterior segment of the right upper lobe. Both cases showed similar histological findings with degenerative atypia.

Table 1 summarizes the clinicoradiological features of previously reported cases of ancient schwannoma arising from the thoracic cavity.

Table 1.

The clinico-radiological features of previously reported cases of ancient schwannoma arising from the thoracic cavity

Author	Age/gender	Site	Clinical presentation	Radiological findings
Petteruti et al. [4]	56/F	Superior right lobe	Inspiratory dyspnoea, dry cough, vague right chest pain and right arm pain	CECT chest: a large well circumscribed heterogeneous tumour of 76,665 cm, with punctuate calcifications and focal low-density areas, located in the posterior mediastinum
Gilbert et al. [8]	53/F	Pleura	Sudden onset breathlessness, cough with expectoration	CECT chest: a large spherical shaped heterogeneously enhancing mass lesion (12 cm) with calcifications in the lower half of posterior third of the right thoracic cavity
Kale et al. [9]	51/F	Chest wall	Pain in the right side of the chest and cough	CECT chest: a right sided pleural based mass 14.1 cm × 9.1 cm × 8.8 cm occupying mid and lower zones of thorax
Quartey et al. [10]	47/M	Posterior mediastinum	Severe mid back pain	CECT chest: a 20.5 × 15.5 × 16.0 cm heterogeneous mass in the left posterior mediastinum with effacement of the left lower lobe
Fay et al. [11]	23/F	Posterior mediastinum	Intermittent cough and vague chest heaviness	CECT chest: a large posterior apical mass with midline shift of the upper mediastinal contents and resultant tracheal narrowing

CECT contrast-enhanced computed tomography

Conclusion

It is crucial for both the clinician and pathologist to be aware of this rare neoplasm so that it is not misdiagnosed or treated like a malignancy. The degenerative nuclear features should not be mistaken for malignancy in the absence of significant mitotic activity.

Author Contribution

SA and SZ were responsible for reporting the case. All authors contributed equally to the literature review, drafting and critically revising the final version of the manuscript. All authors approved the final version of the manuscript.

Declarations

Patient Consent

The authors certify that they have obtained all appropriate patient consent forms.

Conflict of Interest

The authors declare no competing interests.