Ancient Schwannoma of Ansa Cervicalis: A Rare Clinical Entity and Review of the Literature

Abstract

Ancient schwannoma is an uncommon variant of schwannoma, a benign tumor arising from the nerve sheath. It is reported to arise from any nerves except optic and olfactory. However, only six cases of ancient schwannomas arising from ansa cervicalis nerve have been reported to date in English literature. Proper preoperative evaluation is necessary to rule out other causes of neck mass such as thyroid lesions, lymphadenopathy, and carotid body tumor. We report a case of ancient schwannoma arising from the ansa cervicalis nerve. The origin of the lesion from ansa cervicalis was confirmed by intraoperative finding. Postoperative histopathological examination revealed degenerative changes including pleomorphism, cellular atypia, large nuclei with prominent nucleoli, and paucity of mitotic figures. Periphery of the mass showed nuclear palisading with characteristic verocay bodies. Immunohistochemical evaluation for S-100 showed diffuse positivity of the tumor cells, thereby confirming the diagnosis of schwannoma. We consider that schwannoma of cervical region can have origin from any nerve and should try to identify the origin pre- and intraoperatively. The postoperative complications depend on the nerve of origin and the precision of the surgery performed.

Clinical and radiological features of intracranial ancient schwannomas: a single-institution, retrospective analysis

“…AS is a benign tumor (World Health Organization [WHO] tumors of the central nervous system [CNS] grade 1) with a low Ki-67 index (2–3%) [ 36 ], and malignancy is rare. Immunostaining of this tumor is positive for S-100, similar to that for other schwannoma subtypes [ 15 , 25 , 28 , 34 ]. Since diagnosis is difficult based only on clinical and radiological features [ 36 ], pathological diagnosis is important [ 21 ].…”

“…Pathological features of AS include nuclear atypia without mitosis or degenerative changes. Immunostaining of AS is positive for S-100 and SOX10, as for other schwannomas [ 15 , 28 , 39 ]. Although quantitative evaluation has not been performed, AS cases in our cohort were notable for hemosiderin deposition, hyalinized vessels, and inflammatory cell infiltration, in addition to nuclear atypia.…”

“…Hematoxylin- and eosin-stained and immunohistochemical slides were reviewed for all cases by experienced neuropathologists. AS was defined as tissue with conspicuous nuclear atypia with degenerative changes such as hemorrhage with hemosiderin deposition, hyalinized blood vessels, and lymphocytic infiltration, according to the fifth edition of the WHO classification and previous reports [ 12 , 19 – 21 , 28 , 39 ]. While some degree of partial nuclear atypia or degenerative changes are often observed in conventional schwannomas, the diagnosis of AS was made when such findings are diffuse or multiple locations throughout the tumor.…”

An Independent C1 Nerve Root Variant of the Ansa Cervicalis: A Case Report

“…Schwannomas of the AC are very uncommon, with as few as six cases reported. However, schwannomas of other nearby nerves can put the AC at risk of iatrogenic or collateral damage [21,22]. In the current case report, three nerves travelled independently through the cervical region: the vagus nerve, combined inferior root of the AC, and the anomalous independent superior root.…”

Ansa cervicalis: a comprehensive review of its anatomy, variations, pathology, and surgical applications

“…Schwannomas of the ansa cervicalis are rare occurrences [363738394041]. Schwannomas, also known as neuromas, neurilemmomas, or neurinomas, are benign nerve sheath tumor composed of Schwann cells [42].…”