Archives of Medicine and Health Sciences

CASE REPORT
Year
: 2022  |  Volume : 10  |  Issue : 1  |  Page : 91--94

Ancient schwannoma: A rare case report in a 10-year-old child at an unusual site


Sarita Asotra1, Gauri Nakra1, Vineet Aggarwal2,  
1 Department of Pathology, Indira Gandhi Medical College and Hospital, Shimla, Himachal Pradesh, India
2 Department of Orthopedics, Indira Gandhi Medical College and Hospital, Shimla, Himachal Pradesh, India

Correspondence Address:
Dr. Sarita Asotra
Department of Pathology, Indira Gandhi Medical College and Hospital, New Shimla - 171 001, Himachal Pradesh
India

Abstract

Schwannoma is a relatively uncommon, slow-growing, benign tumor that is derived apparently from the Schwann cells lining the nerve sheath. Its most common locations are the flexor surfaces of the extremities, neck, mediastinum, retroperitoneum, posterior spinal roots, and cerebellopontine angle, the occurrence on the lower limbs accounts for 1% of all cases. Ancient schwannoma is considered as a variant of schwannoma, comprising about 10% of all schwannomas. The long-standing schwannoma attributes to degenerative changes and is termed “ancient” schwannoma. We report a rare case of ancient schwannoma of the calf region in a 10-year-old child.



How to cite this article:
Asotra S, Nakra G, Aggarwal V. Ancient schwannoma: A rare case report in a 10-year-old child at an unusual site.Arch Med Health Sci 2022;10:91-94


How to cite this URL:
Asotra S, Nakra G, Aggarwal V. Ancient schwannoma: A rare case report in a 10-year-old child at an unusual site. Arch Med Health Sci [serial online] 2022 [cited 2022 Aug 8 ];10:91-94
Available from: https://www.amhsjournal.org/text.asp?2022/10/1/91/347970


Full Text

 Introduction



Schwannoma (neurilemmoma) is one of the few truly encapsulated benign neoplasms. Its most common locations are the flexor surfaces of the extremities, neck, mediastinum, retroperitoneum, posterior spinal roots, and cerebellopontine angle. The nerve of origin often can be demonstrated in the periphery, flattened along the capsule but not penetrating the substance of the tumor. The great majority of cases occur sporadically, while a small percentage of cases are associated with Type 2 neurofibromatosis (caused by a germline mutation in the NF2 gene located on 22q12, which encodes merlin, also known as schwannomin).[1] Some histological variants of schwannoma that have been described include cellular, plexiform, epithelioid, ancient, and melanocytic types. The ancient schwannoma is an uncommon variant (10% of all schwannomas) that shows histological characteristics of degeneration that develops overtime. We report a case of ancient schwannoma highlighting histopathology. The unique feature in our report is the short duration of the tumor in a 10-year-old child in the subcutaneous plane of the leg.

 Case Report



A 10-year-old male child presented to our hospital with chief complaints of pain and swelling on X-ray in the right calf region [Figure 1]. On local examination, swelling of 6 cm × 4 cm on the posteromedial aspect of the right leg at the middle and lower one-third junction was present with tenderness and normal local temperature. Magnetic resonance imaging was advised to the patient, which revealed a well-defined, fusiform-shaped altered signal intensity lesion in the subcutaneous plane on the right side of the calf region right side probably suggestive of an neurogenic tumour [Figure 2]a, [Figure 2]b, [Figure 2]c.{Figure 1}{Figure 2}

A tru-cut biopsy from the swelling was done, which revealed a spindle cell neoplasm, morphologically suggestive of a benign neural tumor. Excision of the tumor was done by the treating orthopedic surgeon and was sent to our department for histopathological examination. We received an encapsulated single soft-tissue mass, gray-white to gray-brown to tan-brown in color, along with attached muscle fibers measuring 7.5 cm × 4 cm × 3 cm. The cut section revealed gray-white to gray-brown areas with cystic and hemorrhagic areas [Figure 3]. Microscopic examination showed a well encapsulated lesion comprising of hypercellular and hypocellular areas of fascicles of spindle cells.{Figure 3}

Cells showed serpentine nuclei, fine chromatin, eosinophilic fibrillary cytoplasm, nuclear palisading forming verrocay bodies in a myxoid background. In addition shows scattered mast cells, lymphocytes, histiocytes with a focal hypercellular area with long fascicles of benign spindle cells showing hyperchromatic nuclei, inconspicuous nucleoli, a moderate amount of eosinophilic cytoplasm without intervening hypocellular area. In addition, there were also thick-walled blood vessels, marked hemorrhage, cystic change, and dystrophic calcification. There was an absence of pleomorphism, necrosis, and mitotic activity [Figure 4]a, [Figure 4]b, [Figure 4]c, [Figure 4]d. immunohistochemistry done was S-100 positive [Figure 5].{Figure 4}{Figure 5}

Hence, a final diagnosis of benign spindle cell neoplasm suggestive of ancient schwannoma was confirmed.

 Discussion



The schwannoma is a benign tumor of the neural Schwann cells that can potentially occur in any part of the body. It is said to develop from the neural sheaths of cranial (except optic and olfactory), peripheral motor, and sensory and sympathetic nerves. Up to 25% may be associated with Von Recklinghausen's Neurofibromatosis II.[2] It can also arise from any nerve covered with a Schwann cell sheath, which includes the cranial nerves (except for the optic and olfactory), the spinal nerves, and the autonomic nervous system.[3] Schwannoma is a slow-growing benign tumor and may be a large tumor with degeneration, especially when the tumor is situated in the deep regions such as the mediastinum and retroperitoneum.[4] Although they represent the most common benign peripheral nerve sheath tumors, the occurrence on the lower limbs accounts for 1% of all cases.[5] They can occur at all ages, though they are uncommon in children. While literature data indicate that they are most prevalent between the ages of 20 and 50 years. Men and women are equally affected.

Schwannoma with pronounced degenerative changes is known as ancient schwannoma, which is a rare variant of schwannoma and is usually a deeply situated large mass of long duration, representing 0.8% of all soft-tissue tumors.[6] A review of current literature has revealed several reported sites but seldom in the subcutaneous plane of the calf region.

The term ''ancient neurilemmoma'' was first suggested by Ackerman and Taylor in a review of 48 neurogenic tumors of the thorax. The cited authors reported 10 patients with tumors showing features similar to those of typical neurilemmomas but differing in that significant tumor portions contained only a few cells within hyalinized matrices. They found that these features occurred in schwannomas of long duration, and hence, coined the term ''ancient schwannoma.'' Such tumors are characterized by diffuse hypocellular areas, relative loss of Antoni type A tissue, focal accumulations of hyaline material, calcification, cystic necrosis, hemorrhage, and fatty degeneration, including degenerative atypia but without any mitotic activity. Despite these degenerative changes, ancient schwannomas behave similarly to schwannoma. They are benign, slow-growing tumors with rare malignant transformation.[7]

They have a slow-growing pattern, and they never traverse through the nerve but remain in the sheath lying on top of it. This explains why they are usually clinically silent and present often as an incidental finding. Patients may sometimes note a palpable mass.

Clinically, they are slow-growing tumors, and degenerative features develop with time. In the present case, the patient had a history of pain and swelling in the leg for 1 month.

Grossly, the larger schwannomas often contain cystic areas. The microscopic appearance is distinctive with Antoni A and B zones. The Antoni A zones, which in small tumors comprise almost their entirety, are quite cellular, composed of spindle cells often arranged in a palisading fashion or in an organoid arrangement (Verocay bodies). In Antoni B zones, the tumor cells are separated by abundant edematous fluid that may form cystic spaces. Occasionally, isolated cells with bizarre hyperchromatic nuclei are observed (so-called ancient schwannoma) and are of no particular significance. Mitoses are usually absent or rare. Thick-walled hyalinized blood vessels are a characteristic finding, sometimes with thrombosis.[8]

Ancient schwannoma occurs most commonly in deeply situated tissues, and degenerative changes occur usually in long-standing cases of schwannoma. The first case of ancient schwannoma in the pediatric age group was reported in 2010 in Turkey which a 13-year-old male child was diagnosed with ancient schwannoma in anterior chest wall without any malignant transformation and tumor cells showing S-100 positivity.

In our case, we found an unusual finding of degenerative changes in a 10-year-old child in an unexpected location, which raises a suspicion of malignancy. Malignant transformation in a schwannoma is very rare. Diagnosis of ancient schwannoma was given in the present case due to the absence of pleomorphism, mitotic activity, necrosis, and invasion.

Schwannomas stain strongly with S-100 (97%), Leu-7 (57%), and myelin basic protein 44%, confirming the neural origin. However, neurofilament is usually negative due to the absence of neurites. This feature can distinguish schwannomas from the neurofibroma, where nerve fibers are a part of the tumor.[9] CD 56 and calretinin are usually positive in schwannomas, while CD 34 and Factor XIIIa are positive in neurofibromas. These markers can be included in the panel in doubtful cases.[10]

 Conclusion



Ancient schwannoma develops in long-standing cases of schwannoma, and occurs rarely in the pediatric age group and in the calf region. However, ancient schwannoma, when found in the pediatric age group, malignant transformation of the tumor should always be kept in mind, and careful histopathological examination should be done to rule out malignancy.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the legal guardian has given his consent for images and other clinical information to be reported in the journal. The guardian understands that names and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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