Neuroblastoma-like schwannoma of the lower labial mucosa: a rare morphologic variant of peripheral nerve sheath tumor

Case Report: Neuroblastoma-Like Schwannoma in a Domestic Short-Haired Cat

An axillary mass was detected in a 6-year-old, neutered, male, domestic short-haired cat during a wellness exam. Gross examination following surgical removal revealed a discrete, deep subcutaneous, discoid mass that was between 0.5- and 0.7-cm-in-diameter and diffusely firm and white. Histologically, the mass was well-demarcated, partially encapsulated, and expanded the panniculus carnosus. It was composed of tightly packed, giant rosettes of radially arranged fusiform cells stacked in one to 10 layers with peripherally palisading nuclei and with centrally oriented, fibrillary, cytoplasmic processes, and collagenous fibers. Laminin immunoreactivity and ultrastructural examination highlighted a continuous basal lamina outside the plasma membrane of each neoplastic cell. Neoplastic cells were immunoreactive for GFAP, S100, periaxin, and Sox-10 and were immunonegative for synaptophysin, smooth muscle actin, and pancytokeratin. Collective findings were consistent with a diagnosis of neuroblastoma-like schwannoma. This is the first veterinary report of this rare variant of benign schwannoma.

Intramandibular plexiform schwannoma presenting as a nonspecific benign lesion: How specific can we be? A case report with a review of the literature

Schwannoma, a benign nerve sheath tumor, is quite rare and more so in jawbones. We report a rare case of a plexiform variant of mandibular schwannoma in a 12-year-old female with a swelling in the left mandible. Clinical features were suggestive of dentigerous cyst as a result of missing premolars and canine. Occlusal and panoramic radiography revealed an osteolytic lesion with scalloping margins, bicortical plate expansion, and agenesis of several teeth. Odontogenic keratocyst, central giant cell granuloma, odontogenic myxoma, and ameloblastic fibroma were given as radiological differential diagnoses. Histopathological examination revealed features of plexiform schwannoma which was given as the final diagnosis. The lesion was treated with surgical excision. Although odontogenic cysts/tumors are often thought of in differential diagnosis whenever well-defined radiolucencies in the jaw are encountered, it is prudent to include schwannoma. This exceptional case adds light to the fact that schwannoma should not be overlooked though it is a rare possibility and must be included in differential diagnosis of odontogenic cysts/tumors.

Oral neural tumors: Clinicopathologic analysis of 157 cases and review of the literature

Background

Oral neural tumors (ONTs) are rare lesions and represent reactive or neoplastic proliferations of nerve sheath cells. The purpose of the present study is to report the clinical, demographic and histopathologic features of 157 ONTs diagnosed in a single Oral Pathology Department and review the pertinent literature.

Material and Methods

157 cases of ONTs diagnosed during a 44-year period were retrospectively collected and the diagnosis was reconfirmed by studying representative haematoxylin and eosin stained tissue sections. The patients’ gender and age, as well as the main clinical features of the lesions, were retrieved from the biopsy submission forms.

Results

The 157 ONTs represented approximately 0.4% of 35,590 biopsies accessioned during the study period. They affected 71 male and 86 female patients with a mean age of 38.4±18.8 years. They mainly appeared as asymptomatic nodules of normal or white colour on the tongue, lip mucosa and hard palate. The most common ONT was granular cell tumour (38.9%) followed by neurofibroma (19.7%), schwannoma (15.9%), traumatic neuroma (15.9%), palisaded encapsulated neuroma (8.3%) and nerve sheath myxoma (1.3%).

Conclusions

This study confirmed the rarity of ONTs. Their clinical characteristics mimic other oral lesions; thus, microscopic examination is the only mean to arrive at a definitive diagnosis.

Key words:Oral neural tumors; oral neural neoplasms; neurofibroma; oral neurofibroma; schwannoma; oral schwannoma; neurilemmoma; oral neurilemmoma; granular cell tumor; oral granular cell tumor; traumatic neuroma; oral traumatic neuroma; palisaded encapsulated neuroma; oral palisaded encapsulated neuroma.

Comprehensive Analyses of Intraoral Benign and Malignant Nerve Sheath Tumors: The Rare Disease Entities Revisited

INTRODUCTION

Intraoral benign and malignant nerve sheath tumors (BNST and MNST) are rare tumors with non-specific clinical presentations and represent diagnostic and therapeutic challenges. Current knowledge regarding their demographic, clinicopathological features and treatments remains fragmented.

MATERIALS AND METHODS

The original data about patients diagnosed as intraoral BNST and MNST were retrieved from our disease registry (2005-2017). Comprehensive reviews of English and Chinese literature were performed to collect and analyze the epidemiological, clinicopathological data and treatment outcomes about those published cases.

RESULTS

Thirty-four intraoral BNSTs were found at our institution in the past 13 years. Literature reviews identified 354 intraoral BNSTs in 223 articles and 60 intraoral MNSTs in 50 articles. Most intraoral BNSTs and MNSTs were presented in the second to fifth decade of life. Males outnumbered females in MNSTs, while BNSTs displayed a slight female preponderance. The common sites for intraoral BNSTs were parapharyngeal space followed by tongue, whereas mandible was the most common site for MNSTs. Most intraoral BNSTs were presented as slow-growing, painless mass or swelling, while MNSTs usually appeared as painful and invasive mass with discomfort. Surgical excision was preferred for intraoral BNSTs with excellent prognosis. Complete resection was indicated for intraoral MNST with dismal prognosis as evidenced by much recurrence, metastasis, and death.

CONCLUSION

Intraoral BNST and MNST are rare diseases which should not be ignored when intraoral painless or painful mass/swelling is found. Surgical excision is indicated for intraoral BNST with favorable outcomes. However, further investigations are warranted to optimize the treatment for intraoral MNST to improve its prognosis.

Neuroblastoma-like schwannoma with giant rosette: A potential diagnostic pitfall for hyalinizing spindle cell tumor

Neuroblastoma-like schwannoma (NLS) is a rare variant of a common tumor. The aim of this study is to discuss, through a literature review, the differential diagnoses of NLS while emphasizing the importance of ancillary studies. So far, 24 cases have been reported. We describe an additional case in a 64-year-old woman who had a 3-cm subcutaneous tumor on her flank. The histological examination showed an encapsulated neoplasm. Most of the tumor was made of giant rosettes. These rosettes had several sizes reaching 2.6 mm. They showed a palisade of rounded cells. Nuclei were hyperchromatic but bland. The center was made of eosinophilic cores of collagenous radiating fibrils. Neoplastic cells stained strongly for S-100 protein. In the capsule, perineural cells stained for epithelial membrane antigen (EMA). No expression of Mucin 4 (MUC4) was present. This was consistent with NLS. The same peculiar appearance of giant rosettes has been described in hyalinizing spindle cell tumor with giant rosettes (HSCT). We propose the term "neuroblastoma-like schwannoma" when there are small rosettes, "HSCT-like schwannoma" for tumors with giant rosettes and "collagen-rich schwannoma" when there are "ill-defined" structures reminiscent of rosettes. Immunohistochemical panel containing S100, EMA, and MUC4, as well as molecular testing when needed should be performed.

Palatal schwannoma in a young female patient: report of a case and review of the literature

BACKGROUND

A few cases of oral schwannomas in paediatric patients have appeared in the literature so far; however, there are no studies focusing solely on paediatric oral schwannomas. The aim of this study is to report a case of palatal schwannoma in a young female patient and review the pertinent literature on oral schwannomas in paediatric patients.

CASE REPORT

A 12-year-old girl presented with a growing swelling of 2 weeks duration on the hard palate. With a provisional diagnosis of a salivary gland neoplasm an incisional biopsy was performed under local anesthesia and the histologic examination disclosed an Antony A type schwannoma.

TREATMENT

Complete surgical resection of the lesion was performed under local anaesthesia through a palatal mucosa incision and paraffin gauze was sutured on the surgical area for protection during secondary healing. The bone underlying the tumor was normal. The postoperative period was uneventful and 2 weeks after excision the gauze were removed.

FOLLOW-UP

There have been no signs of recurrence during a 18-month follow up period.

CONCLUSION

A palatal swelling in a child or adolescent may represent a neoplasm, such as a schwannoma and requires careful clinical and radiographic evaluation of the dentition.

Clinical features and management of schwannoma affecting the upper and lower lips

Head and neck schwannomas comprise 25-40% of all schwannomas, with presentation on the lips as the rarest and most surgically complicated site for perioral tumors. A systematic literature review was conducted to include 21 cases of patients with schwannoma of the upper or lower lips. The majority of patients presented with a single, painless, well-encapsulated nodule on the upper or lower lips. The nodules were consistently slow-growing, with an average 29.3 months from symptom onset to clinical presentation. Most cases were complicated by profound cosmetic disfigurement as well as dysphagia, dysarthria, snoring, and/or sleep apnea. Overall, histological analysis was consistent with classic schwannoma, and all cases were treated via complete surgical excision, and for malignant tumors, additional therapy was utilized. All but four cases achieved full remission by final follow-up. Recurrence rate for benign lip schwannomas was 5.3%, which is remarkably different from the standard recurrence rate of 8-24% for benign peripheral schwannomas. Additionally, the proportion of malignant tumors was greater for lip schwannomas than other schwannomas. Lip schwannomas demonstrate different characteristics than schwannomas from other locations on the body, and these remarkable differences highlight significant implications for clinical practice. Complete excision is the primary mode of treatment with overall excellent postoperative prognosis and rare instances of recurrence. Given the rarity of this tumor, this review of available cases serves to comprehensively describe clinical presentation and surgical treatment approaches to upper and lower lip schwannomas.

Neuroblastoma-like schwannoma of the skull base: an enigmatic peripheral nerve sheath tumor variant

Neuroblastoma-like schwannoma is an extremely rare histological variant of schwannoma, which histologically mimics a malignant small round cell tumor. Only 19 cases have been reported in the literature to date. We report a case of this tumor located at the skull base in a 44-year-old woman who presented with symptoms of right-sided earache and hearing loss. MRI revealed a large, lobulated, extra-axial mass measuring 8.8 cm × 3.6 cm × 4.2 cm in the floor of the middle and posterior cranial fossa. Microscopic examination revealed a perplexing histopathology with peculiar collagenous rosettes. Differential diagnoses included a broad range of benign and malignant tumors. Typical schwannoma seldom poses a difficulty in diagnosis; however, this unusual variant is a diagnostic challenge which requires an extensive clinico-radiological correlation and immunohistochemical work-up. Hence, knowledge of this entity is a must to avoid erroneous diagnosis and inappropriate treatment.