A schwannoma of the greater petrosal nerve located within the petrous apex and treated with stereotactic radiotherapy

Intraosseous Schwannoma of the Frontal Bone: A Case Report and Review of the Literature

Intraosseous schwannoma is a rare diagnosis, particularly so in the skull. Accordingly, little data exists to unify common features of this disease. Here, we present the fourth known case of a primary intraosseous schwannoma of the frontal bone: a 46-year-old male with severe, progressive headache and an osteolytic frontal bone lesion. Gross total resection of the lesion was performed with excellent clinical outcome. Histological analysis confirmed the diagnosis. The limited existing literature on this topic was reviewed to identify emerging trends surrounding presenting symptoms and treatment. Early literature suggests symptoms are often nonspecific, except for lesions of the petrous apex. No cases of recurrence have been demonstrated after gross total resection, though incomplete resection has been associated with recurrence. This diagnosis appears to be becoming a more often-considered differential for osteolytic, expansile skull lesions.

Intraosseous schwannoma in the clivus mimicking chordoma treated with endoscopic endonasal surgery: A case report

Background:

Intraosseous schwannomas are extremely rare and they have not yet been reported to occur in the clivus. We report a schwannoma in the clivus mimicking chordoma and review intraosseous schwannomas of the skull.

Case Description:

A 62-year-old man presented with gradually worsening hoarseness with dysphagia and atrophy of the left tongue, trapezius muscle, and sternocleidomastoid muscle. Magnetic resonance imaging showed that the tumor was mainly located in the clivus, and a computed tomography (CT) scan revealed an osteolytic lesion with expansion of the clivus and preservation of the bony cortex. Endoscopic endonasal surgery was performed to diagnose and treat symptoms. The tumor was subtotally removed without any complications. The histopathological findings revealed typical schwannoma, which showed Antoni A and Antoni B patterns positive for S100 protein. Based on the preoperative imaging, intraoperative and histopathological findings, the tumor was considered to be an intraosseous schwannoma in the clivus, and no recurrence was observed after 1 year of postoperative follow-up.

Conclusion:

Even though the intraosseous schwannoma in the clivus is uncommon, it should be considered as a differential diagnosis if an expansive lesion without destruction of the cortical bone is shown on CT as well as iso-hyperintensity on T2-weighted magnetic resonance imaging.

Large Intraosseous Schwannoma in Petrous Apex Presenting with Intratumoral Hemorrhage

BACKGROUND

Intracranial schwannomas are rarely confined to the skull. We here report a large schwannoma localized in the petrous apex that presented with intratumoral hemorrhage.

CASE DESCRIPTION

A 35-year-old woman with mild hearing disturbance and ear fullness underwent computed tomography scan and magnetic resonance imaging, which demonstrated a tumor accompanied with intratumoral hematoma in the right petrous apex. Bone marrow was totally destroyed, but the bone cortex was relatively preserved. Pathologic specimen showed that the tumor was composed of proliferation of elongated neoplastic cells and positive for S-100 protein. It showed a nuclear palisading pattern, compatible with schwannoma. The lack of any cranial nerve signs and relative preservation of canals through which cranial nerves pass suggested the neurilemma cells surrounded vessels or mismigrated fetal neurilemma cells in the petrous apex as origin of the tumor. Benign nature of the tumor and total disappearance of the symptoms, supposedly due to the spontaneous absorption of the hematoma, made the patient choose a wait-and-watch approach. Magnetic resonance imaging studied 7 years after the diagnosis showed significant decrease of the tumor volume and disappearance of the hematoma.

CONCLUSIONS

Although it is a large intraosseous schwannoma in the petrous apex, it has a benign nature, its size is reduced due to the hematoma absorption, and the patient is asymptomatic. We observed the patients for 7 years after the diagnosis.

Solitary intraosseous schwannoma of the base and vault of the skull: a summary review of such unusual location

Intra-osseous schwannoma is a rare mesenchymal tumor. Although, the head and neck region is one of the most common sites for schwannomas, its location at the skull bone is uncommon and accounted for less than 0.2% in the largest series of bone tumors ever reported. Furthermore, it is most often a benign tumor, malignant transformation is exceedingly rare. Clinical presentation is non-specific, most often symptoms are associated with compression and invasion of adjacent organs. Neuro-imaging features are non-specific and the diagnosis is based on histological examination with immunohistochemical study. Surgery remains the aim of treatment. However, radiation therapy could be an interesting therapeutic option in unresectable tumors. This systemic review offers new clinicopathological data useful for better defining the diagnosis and clinicopathological behavior of schwannoma. The purpose of this work is to raise awareness among clinicians adding this clinical entity as a differential diagnosis when a mass of skull bone is identified.