Malignant epithelioid schwannoma arising in a benign schwannoma. A case report

Malignant peripheral nerve sheath tumors arising from schwannomas: case series and literature review

A malignant peripheral nerve sheath tumor (MPNST) arising from a schwannoma is extremely rare, with limited literature on its clinicopathologic features. Here, we present a case series and literature review on patients with MPNSTs arising from schwannomas. We performed a retrospective review of patients from our institution's records to identify those with MPNSTs arising from schwannomas. We conducted a search for additional cases from the literature utilizing PubMed. 20 patients (including 2 at our institution and 18 from 16 prior publications) were identified. The patients aged 22-93 (mean 52) years, and 63% were females. Histologically, while most MPNSTs arising from schwannomas were of epithelioid-type, 7 tumors (including 2 at our institution) were of conventional spindle-cell type. All 20 patients underwent surgical excision, while a subset received additional radiotherapy and/or chemotherapy. In 17 patients with available follow-up, the overall survival was 2-72 (median 12) months. MPNSTs rarely arise from schwannomas and should be considered in patients with a clinical diagnosis of schwannoma, however, with atypical radiologic or clinical features. MPNSTs arising from schwannomas can show epithelioid or spindle-cell histology and harbor an aggressive course, even with surgical excision and adjuvant treatment.

TIM-3 plays a more important role than PD-1 in the functional impairments of cytotoxic T cells of malignant Schwannomas

Cancer immunotherapy using cytotoxic T cells demonstrates dramatic survival benefits in lymphomas, but its efficacy in solid tumors is limited. Here, we investigated the possibility of using cytotoxic T cells to treat malignant Schwannoma, a rare but aggressive nerve sheath tumor, by examining the native T-cell immunity in the host. We found that compared to CD8⁺ T cells from healthy controls or benign Schwannoma patients, the CD8⁺ T cells from malignant Schwannoma patients were present at normal frequencies but were substantially enriched with PD-1^-TIM-3⁺ and PD-1⁺TIM-3⁺ cells. Compared to the PD-1^-TIM-3^- CD8⁺ T cells, the PD-1^-TIM-3⁺ and PD-1⁺TIM-3⁺ CD8⁺ T cells presented significantly lower proliferation capacity, reduced interleukin 2 and interferon gamma expression, and/or dramatically decreased perforin and granzyme B secretion, indicating a whole-spectrum immunosuppression and reduced cytotoxicity. TIM-3 expression alone was associated with lower proliferation and less perforin and granzyme B secretion, whereas PD-1 expression alone was not associated with functional impairments, suggesting that TIM-3 expression was a better marker of exhausted CD8⁺ T cells. The expression of galectin 9, a TIM-3 ligand, in CD4⁺ Th cells was significantly elevated in malignant, but not benign, Schwannoma patients and were enriched in CD25⁺ Treg cells. Both the PD-1^-TIM-3⁺ and PD-1⁺TIM-3⁺ CD8⁺ T cells responded to Treg-mediated and galectin 9-mediated suppression, whereas the PD-1⁺TIM-3^- CD8⁺ T cells only responded to Treg-mediated suppression. In resected tumors, the malignant Schwannomas had more tumor-infiltrating CD4⁺ and CD8⁺ T cells than the benign Schwannomas, but a large fraction of these tumor-infiltrating CD4⁺ and CD8⁺ T cells expressed PD-1 and/or TIM-3, which indicated that their antitumor immunity was compromised. Together, our results suggested that PD-1 and TIM-3 blockade might be necessary in developing effective immunotherapeutic strategies in malignant Schwannoma, in which TIM-3 may play a more important role.

Role of endoscopic surgery in the management of sinonasal and skull base schwannomas

BACKGROUND

The purpose of this study was to report our experience with the endoscopic management of sinonasal schwannomas, analyzing the advantages, limitations, and outcomes of the technique.

METHODS

A retrospective analysis was carried out on 11 patients treated endoscopically between 2000 and 2014 at a single institution.

RESULTS

Eight patients underwent an exclusive endoscopic endonasal approach, whereas, in 3 patients, an osteoplastic flap was combined because of massive or lateral frontal sinus involvement. The tumor extended into the orbit in 5 cases, and involved the skull base in 5 patients who required a concomitant endoscopic duraplasty. No evidence of disease was observed in 10 patients after a mean follow-up of 90.1 months (range, 14-189 months). One patient was alive with persistence of disease, although asymptomatic.

CONCLUSION

The endoscopic endonasal approach is a valid alternative for the vast majority of sinonasal schwannomas with minimal morbidity for the patient. © 2016 Wiley Periodicals, Inc. Head Neck 38: E2074-E2082, 2016.

Endoscopic Resection of Sinonasal Tract Schwannoma: Presentation, Treatment, and Outcome in 10 Cases

BACKGROUND

Sinonasal schwannoma (SNS) is a rare sinonasal tract tumor whose presentation is similar to that of other benign nasal tumors. Very few case series appear in the literature. This study aims to describe the presentation, treatment, and outcome of 10 SNS cases from 3 referral centers.

METHODS

All SNS cases were analyzed retrospectively. Patient demographics, tumor data, surgical procedures, and outcome were recorded.

RESULTS

Five males and 5 females (mean age, 49.1 ± 21.4 years) were included in the study. The tumor was on the left side in 9 patients and on the right side in 1. It originated in the middle turbinate in 4 cases, the ethmoid and sphenoid sinuses in 2 cases, and the nasal septum and infratemporal fossa in 1 case each. Tumor resection was done endoscopically in all cases, and there was no need for an external procedure, and 5 patients did not require a sinusotomy. All 10 patients remained disease-free after a mean follow-up of 65.3 months (range, 2-120 months).

CONCLUSION

Safe and effective endoscopic resection of SNS is feasible. If the tumor is contained within the nasal cavity, simple tumor excision without sinusotomy can be enough to resect the tumor. In more extensive disease, a wider endoscopic approach may be needed, but an external approach was not necessary in this series.

Challenging epithelioid mesenchymal neoplasms: mimics and traps

Epithelioid mesenchymal malignancies represent a major diagnostic challenge. Epithelioid morphology can be observed in a variety of soft tissue neoplasms, however there exist specific subtypes in which an epithelioid apperance constitutes the most distinctive morphological feature. Moving from epithelioid sarcoma of Enzinger (the prototype of sarcoma with epithelioid morphology), this review will focus on the most relevant entities: namely epithelioid haemangioendothelioma and angiosarcoma, pseudomyogenic haemangioendothelioma, epithelioid malignant peripheral nerve sheath tumour, epithelioid sclerosing fibrosarcoma, epithelioid pleomorphic liposarcoma, alveolar soft part sarcoma, and undifferentiated soft tissue sarcoma with epithelioid morphology. Differential diagnoses and major pitfalls will be discussed in detail.

Unique surgical issues in the management of a giant retroperitoneal schwannoma and brief review of literature

Ancient Schwannoma, though benign, can cause diagnostic dilemma because of its clinical presentation and imaging features. We report the management of a giant retroperitoneal schwannoma in a 19-year-old young lady who presented with lower abdominal distension. CT scan reported a large heterogenous lesion in the abdominopelvic retroperitoneum (42 cm × 16 cm × 16 cm) as a malignant tumor. The unique problems we encountered were the enormous size, the location of major part of the tumor in the pelvis, the need for fertility preservation, the external iliac vessels stretching over the tumor making mobilization surgically demanding, and the prospects of neurological deficits. An en bloc resection of schwannoma with common iliac, external iliac and internal iliac veins, internal iliac artery, femoral and obturator nerves, and iliopsoas muscle was done maintaining oncological principles. External iliac artery that was cut to facilitate tumor mobilization was reanastomosed at the end of the procedure. Postoperatively patient had uneventful recovery with patchy sensory loss, foot drop, and quadriceps weakness which was rehabilitated with a foot drop splint and active physiotherapy.

Unique case of malignant transformation of a vestibular schwannoma after fractionated radiotherapy

OBJECTIVE

Malignant transformation of vestibular schwannoma is considered a rare clinical entity. Radiotherapy, as a treatment option for vestibular schwannoma, is regarded as a potential risk factor for secondary malignancy. Recently, radiotherapy with dose fractionation has been proposed, intended to diminish the risk of radiation-induced neuropathy.

CASE PRESENTATION

The aim of the present study is to report the first case, to the best of our knowledge, of malignant transformation of a residual vestibular schwannoma 19 years after fractionated radiotherapy, describing its characteristics with regard to those previously reported in the literature.

CONCLUSIONS

The main purpose of the present work is to state that the knowledge of the iatrogenic potential pitfalls of any technique of radiotherapy in clinical oncology is becoming a necessity. Finally, our report demonstrates that the irradiated patients must be monitored for life because a secondary malignancy may appear after a very long delay.

Benign ancient schwannoma of the abdominal wall: an unwanted birthday present

Background

There has been a recent growth in the use of whole body Computerised Tomography (CT) scans in the private sector as a screening test for asymptomatic disease. This is despite scant evidence to show any positive effect on morbidity or mortality. There has been concern raised over the possible harms of the test in terms of radiation exposure as well as the risk and anxiety of further investigation and treatment for the large numbers of benign lesions identified.

Case Presentation

A healthy 64 year old lady received a privately funded whole body CT scan for her birthday which revealed an incidental mass in the right iliac fossa. This was investigated with further imaging and colonoscopy and as confident diagnosis could not be made, eventually excised. Histology demonstrated this to be a benign ancient schwannoma and we believe this to be the first reported case of an abdominal wall schwannoma in the English literature

Conclusions

Ancient schwannomas are rare tumours of the peripheral nerve sheaths more usually found in the head, neck and flexor surfaces of extremities. They are a subtype of classical schwannomas with a predominance of degenerative changes. Our case highlights the pitfalls of such screening tests in demonstrating benign disease and subjecting patients to what turns out to be unnecessary invasive investigation and treatment. It provides evidence as to the consequences of the large number of false positive results that are created by blind CT scanning of asymptomatic patients i.e. its tendency to detect pseudodiesease rather than affect survival rates. Should the number of scans increase there may be an unnecessary burden on NHS resources due to the large numbers of benign lesions picked up, that are then referred for further investigation.

[Peripheral nerve tumors]

Peripheral nerve tumors are most often benign tumors of the nerve sheath; uncommonly they come from the nerve cells or are metastatic tumors. A precise diagnosis is required for well-adapted and effective treatment, as is good knowledge of fibromatosis diseases. In some cases, the diagnosis of the nerve tumor will lead to a diagnosis of phakomatosis. Surgical treatment must be clearly discussed, which, in case of schwannomas gives very good functional results. Primitive malignant tumors remain an unsolved therapeutic problem.

Tarsal tunnel syndrome associated with a neurilemoma in posterior tibial nerve: a case report

Compression neuropathy of the posterior tibial nerve (PTN) and its branches in the tarsal tunnel is called tarsal tunnel syndrome (TTS) and has various aetiologies. Space-occupying lesions in the tunnel, such as neurilemomas, can cause such a disease. When a neurilemoma occupies the tarsal tunnel, it can compress the PTN directly or indirectly and results in restriction of the tunnel volume. Symptoms due to this restricted volume may vary in TTS. A case of neurilemoma of PTN in tarsal tunnel with a complaint of posteromedial ankle intermittent pain in a 20-year-old patient is presented here. A mass was observed at the ankle posteromedially during clinical examinations and the patient underwent magnetic resonance imaging (MRI) and radiological investigation. Radiographic evaluation of the ankle was normal. However, MRI was revealed a mass adjacent to the PTN in the tarsal tunnel. An ovoid, smooth-surfaced, encapsulated and eccentrically localized mass in the PTN was detected at surgery. The mass was excised from the nerve and pathological evaluation revealed a neurilemoma (schwannoma). Neurilemomas arising from the PTN in the tarsal tunnel should always be kept in mind as a differential diagnosis when a patient complains of a posteromedial ankle pain. Since it is a space-occupying lesion and encapsulated tumor in the tarsal tunnel, simple surgical resection is curative without a distinct morbidity.

Schwannoma of the sinonasal tract: a clinicopathologic and immunohistochemical study of 5 cases

CONTEXT

Peripheral nerve sheath tumors are soft tissue neoplasms rarely encountered in the nasal cavity and paranasal sinuses.

OBJECTIVE

To describe the clinicopathologic and immunohistochemical features of a series of schwannomas of the sinonasal tract.

DESIGN

Surgical pathology files were searched for the diagnosis "sinonasal schwannoma." All histologic documents and clinical data were reviewed. Immunohistochemistry was performed on paraffin-embedded tissue with antibodies to S100 protein, epithelial membrane antigen, CD34, and MIB-1. RESULSTS: Five cases of sinonasal schwannoma were retrieved; patients included 3 women and 2 men, aged 20 to 56 years. Three cases were located in the ethmoid sinus. Clinical symptoms were nonspecific (nasal obstruction, epistaxis, and anosmia). All tumors were treated with conservative surgical resection. Pathologic examination showed a spindle cell proliferation without encapsulation in all cases. No cytologic atypia was seen, and the mitotic activity was low (<3 mitotic figures/10 high-power fields). Immunohistochemistry showed diffuse positivity with S100 protein and negativity with CD34 and epithelial membrane antigen. MIB-1 staining was low (1%-5% of tumor cell nuclei stained). During the follow-up (median, 6 years), no recurrence or metastasis was observed.

CONCLUSIONS

Schwannoma is a very unusual tumor of the sinonasal tract and is associated with nonspecific symptoms. Histologically, sinonasal schwannomas differ from schwannomas of other locations by their lack of a peripheral capsule and possible ulceration of the epithelial covering. Sinonasal schwannomas are treated with conservative surgical resection and have an excellent prognosis.

Isolated peripheral neurilemoma attached to the tendon of the flexor digitorum longus muscle

Neurilemomas are benign tumours arising from peripheral nerves with a Schwann cell sheath. They are normally painless and slowly growing, rarely causing motor disturbances. Neurilemomas are most common in the cranial nerves, in the trunk, the upper and lower extremities, but may appear anywhere. Especially rare are neurilemomas of the lateral peroneal nerve in the region of the fibular head and in the foot. We present the first detailed report of a neurilemoma localized between the Achilles tendon and the flexor digitorum longus muscle with separation of the tumour from the tibial nerve.

Subcutaneous malignant epithelioid schwannoma with cartilaginous differentiation

BACKGROUND

Malignant epithelioid schwannoma is a rare tumor. The aim of this study is to describe a case of subcutaneous malignant epithelioid schwannoma with cartilaginous differentiation.

METHODS

Histological, immunohistochemical, and ultrastructural examinations were performed on a tumor that arose on the back of a 37-year-old woman.

RESULTS

Histologically, the tumor predominantly consisted of small, round or polygonal cells arranged in cords or nests. Immunohistochemical study revealed that the tumors cells were positive for vimentin, S-100 protein, glial fibrillary acidic protein and neuron specific enolase. The cells were negative for HMB-45, keratin, epithelial membrane antigen, and CAM5.2. Electron microscopic study showed closely associated cells with undifferentiated features. The cells were devoid of external laminae and cellular junctions.

CONCLUSION

Malignant epithelioid schwannoma should be pathologically differentiated from other epithelioid tumors with cartilaginous elements.

Papillary meningioma in the dog: a clinicopathological study of two cases

Two cases of canine papillary meningioma are reported. The first animal, an 11-year-old male Boxer, presented with vestibular ataxia and the tumour was located in the left pontomedullary region. The second animal, a 15-year-old female cross-bred Miniature Poodle, presented with dementia, truncal ataxia and hypermetria, and the tumour was located in the right semilunar ganglion of Gasser. In the first case, histopathological examination showed that the papillary pattern merged with a typical syncytial meningioma, with extensive areas of necrosis. In the second case, the multilobular tumour had lobules with a purely syncytial, fibrous or transitional histological pattern, and lobules with intermingling papillary and secretory histological patterns. Both tumours exhibited histological features of malignancy, but evidence of remote metastasis was not found.

Expanding the spectrum of malignant change in schwannomas: epithelioid malignant change, epithelioid malignant peripheral nerve sheath tumor, and epithelioid angiosarcoma: a study of 17 cases

Schwannomas (neurilemmomas) rarely undergo malignant change, most often in the form of either malignant peripheral nerve sheath tumor (MPNST) or angiosarcoma. We characterize the clinical features and the histopathologic spectrum of 17 schwannomas with evidence of malignant change. The study group comprised 7 males and 10 females with an age range of 16 to 76 years, (median, 40 yrs). None of the patients had neurofibromatosis. Lesions ranged in size from 0.6 to 10.5 cm (median, 4.0 cm) and arose mainly in the limbs/limb girdles (7 cases) or head and neck region (7 cases). All tumors contained areas of conventional benign schwannoma. Four cases of pure epithelioid malignant peripheral nerve sheath tumor (EMPNST) were identified, three of which showed immunopositivity for S-100 protein. Four angiosarcomas were identified, predominantly epithelioid-type. Ten schwannomas had an appearance that we have designated epithelioid malignant change (EMC) and, in one of these, EMC coexisted with EMPNST. Large epithelioid cells with abundant eosinophilic cytoplasm, vesicular chromatin, and prominent nucleoli (morphologically similar to cells of EMPNST) were distributed throughout the schwannoma--singly, in clusters, and in one case a microscopic nodule of such cells was also present. These large epithelioid cells were strongly positive for S-100 protein. Although follow-up data so far are limited, 1 of 5 patients with EMC in whom meaningful follow up was available developed repeated local recurrence (median follow up, 21 mos), one patient each with EMPNST and angiosarcoma died of local and metastatic disease. Pure EMPNST is rare; however, we confirm the tendency of MPNST to show epithelioid cytomorphology when arising in a benign schwannoma. We also confirm the distinctive (albeit infrequent) tendency of angiosarcoma to arise in schwannomas. We describe EMC in schwannomas and suggest that this represents a putative precursor lesion of EMPNST. At this time, we do not have an explanation for the tendency of schwannomas to show epithelioid cytomorphology when they undergo malignant change.

Fine-needle aspiration cytology of "ancient" schwannoma

The term "ancient" schwannoma was proposed for a group of neural tumors showing degenerative changes and marked nuclear atypia. Prior to the realization that the observed atypia was a regressive phenomenon, many of these lesions were erroneously diagnosed as sarcomas. Fine-needle aspiration (FNA) cytologic material from five patients is included in this study. Tissue examined histologically included four resected tumors and 18 gauge core biopsies of one tumor. Aspirates of ancient schwannoma showed many of the same features as FNA of regular schwannoma: aggregates of spindled cells with indistinct cytoplasm and elongate nuclei with blunt point ends. The feature unique to these lesions was nuclear pleomorphism, which was identified in all aspirates. Nuclear inclusions were identified in all but one case. Cystic degeneration, xanthomatous changes, and perivascular sclerosis were identified in excised lesions. Ancient schwannomas show most of the FNA features of benign schwannomas but can demonstrate marked nuclear atypia. The FNA features of ancient schwannoma are important to note because of the potential to confuse this lesion with a more serious one such as sarcoma on FNA.

Schwannoma with features mimicking neuroblastoma: report of two cases with immunohistochemical and ultrastructural findings

OBJECTIVE

A study of two cases of a rare variant of benign schwannoma showing areas mimicking neuroblastoma/peripheral primitive neuroectodermal tumour (PNET).

METHODS

Sections of formalin fixed, paraffin embedded specimens were studied by tinctorial stains and immunohistochemistry, and the tissue retrieved from formalin was examined by electronmicroscopy in one case.

RESULTS

The tumours were small and subcutaneous. Both showed features of benign schwannoma; one had a multinodular plexiform pattern. In addition, rosette-like structures consisting of collagenous cores surrounded by small round cells or slightly larger epithelioid cells were present. Tumour cells were positive for S100 protein, Leu7, and in one case GFAP, but were negative for neurofilament protein, synaptophysin, and MIC2. Type IV collagen surrounded individual cells. Electronmicroscopy in case 2 confirmed schwannian features (lamina, processes) and failed to show features of neuroblastoma (neuroendocrine granules).

CONCLUSIONS

Benign schwannomas may contain rosette-like structures mimicking neuroblastoma/PNET. The techniques used confirmed schwannian differentiation only and eliminated neuroblastoma/PNET. These uncommon variants should be recognised by practising histopathologists to avoid erroneous diagnoses and inappropriate treatment.

Gangliocytic paraganglioma of the duodenum: report of a case with immunocytochemical and ultrastructural investigation

A case of gangliocytic paraganglioma is reported in a 70-year-old female presenting as a polypoid tumor of the second portion of the duodenum. Immunohistochemical and ultrastructural features of the tumor indicate that gangliocytic paraganglioma of the duodenum (GPD) represents an unique tumor originating from the neuroectodermal derivative exhibiting dual phenotypic expression toward paraganglionic and epithelial (neuroendocrine) cells. These findings correlate well with the literature and it is further suggested that GPD belongs to the histopathologic spectrum of tumors derived from the neural crest. The findings offer a plausible explanation for histogenetic possibilities of the occurrence of pure epithelial tumors (i.e., carcinoid-like tumors) in the paraganglionic systems. The patient remains with no evidence of disease 4 years following a simple polypectomy.

Fine-needle aspiration of epithelioid malignant peripheral nerve sheath tumor (epithelioid malignant schwannoma)

The epithelioid variant of malignant peripheral nerve sheath tumor (MPNST), also known as malignant epithelioid schwannoma, is a relatively rare and recently characterized clinicopathologic entity. The epithelioid variant of MPNST shares many clinical features with conventional MPNST but is characterized by different histologic and cytologic features. These include a distinctive nesting pattern and an abundance of cytoplasm not seen in histology of conventional nerve sheath tumors. Cytologically, the epitheliod variant shows a propensity to cellular discohesiveness and a plasmacytoid or epitheliod appearance that is in contradistinction to the spindled appearance of the usual MPNST. Herein, we report our experience with fine-needle aspiration (FNA) of two epithelioid malignant schwannomas and discuss the FNA cytologic differential diagnosis.

Peripheral nerve sheath differentiation in malignant soft tissue tumours: an ultrastructural and immunohistochemical study

Thirteen soft tissue sarcomas with ultrastructural evidence of nerve sheath differentiation were investigated by immunohistochemistry. Three arose in a major nerve or nerve trunk and four patients had von Recklinghausen's neurofibromatosis. Ultrastructurally, 10 cases showed variable differentiation towards Schwann cells, two resembled perineurial cells and one tumour had features suggestive of both cell types. Immunostaining for S-100 protein was positive in eight Schwann cell tumours, negative in the other two Schwann cell tumours and negative in those with perineurial-like cells. No cases demonstrated epithelial membrane antigen, so that the existence of perineurial cells in malignant nerve sheath tumours remains immunohistochemically unsubstantiated; it may be that the perineurial-like cells are merely incompletely differentiated Schwann cells, with nerve sheath differentiation manifesting a continuous spectrum. Leu 7 was detected in four Schwann cell tumours, three of which were ultrastructurally well differentiated. Cytokeratin and desmin were demonstrated only in an undifferentiated pleomorphic area of one Schwann cell tumour. Electronmicroscopy can aid diagnosis by revealing nerve sheath differentiation in malignant soft tissue tumours without demonstrable S-100 protein.

A very large neurilemmoma of the anterior interosseous nerve

A very large neurilemmoma of more than 15 years duration, arising from the anterior interosseous nerve, is reported. To our knowledge, this is the largest ever described. While the symptoms and all other diagnostic findings suggested that the neurilemmoma originated from the median nerve, it needed angiography to provide the final diagnosis.

Nasal schwannoma

A 36-year-old man with a nasal septal mass is presented. The diagnosis of a benign neoplasm arising from peripheral nerve Schwann cells was made by excisional biopsy. A benign nerve sheath tumor may be either a schwannoma or neurofibroma. Schwannomas may be distinguished from neurofibroma by clinical and histologic criteria. Malignant degeneration and intracranial extension may complicate the course of a nasal schwannoma. Complete excision is the preferred therapy.

Cellular schwannoma. A clinicopathologic study of 57 patients and 58 tumors

The cellular schwannoma is a variety of schwannoma with a predominantly cellular growth but no Verocay bodies. Because doubt has been raised about the original assessment of this tumor as benign, the clinical and pathologic characteristics of 58 cellular schwannomas from 57 patients were reviewed. The patients were most often middle aged (63% were female), and their tumors most commonly were painless masses with a predilection for the paravertebral region of the retroperitoneum, pelvis, and mediastinum. Most tumors were solitary and encapsulated, and an associated nerve was identified for 43% of the cases. Electron microscopic and immunohistochemistry studies confirmed the tumor's Schwann cell nature. Worrisome features such as bone erosion, hypercellularity, foci of necrosis (four tumors), hyperchromasia, nuclear pleomorphism, and the presence of mitotic figures led to a malignant diagnosis for 28% of the cases. Treatment in all but one case was surgical excision. Two patients also received radiation therapy and chemotherapy. Follow-up of from 1 year to 24 years, 7 months (median of 6 years and mean of 7 years) for 61% (35 cases) of the cases reveals three patients with a local recurrence but no cases in which the tumor metastasized or the patient died of the tumor. Awareness of this tumor type is important so that the surgeon will avoid unnecessary sacrifice of functionally important nerves attached to these tumors and so that needless adjuvant radiation and chemotherapy will not be instituted.

Benign schwannoma and parathyroid adenoma occurring in the nonradiated neck: report of two cases

The late occurrence of multiple neoplasms in the previously radiated neck is a well-known association. However, multiple tumours in the nonradiated neck remain a rare finding. This paper presents two cases of the infrequently seen schwannoma occurring with a parathyroid adenoma without antecedent history of radiation or neurofibromatosis.

Malignant nerve sheath tumour arising in a benign ancient schwannoma

A malignant nerve sheath tumour arising in a longstanding benign schwannoma in a 75-year-old woman is described. Malignant change of this kind is extremely rare; there appear to be only four convincing previously reported cases.

Malignant schwannoma. A case report and review of the literature

A rare case of a malignant schwannoma presenting as a central fracture-dislocation of the acetabulum is reported. Histological examination showed a high-grade sarcoma. A pleural metastasis was present. A local reconstructive procedure consisting of local tumor excision with an acetabular prosthetic replacement and adjunctive radiation therapy was elected for the patient, who had a short-term prognosis.

Malignant epithelioid schwannoma: a light microscopic and immunohistochemical study

Malignant epithelioid schwannoma is a rare variant of malignant nerve sheath tumor that can be confused with both other neuroectodermal neoplasms and carcinomas. The light microscopic and immunohistochemical findings of a malignant epithelioid schwannoma arising in the mandibular region of a 27-year-old female are described. The differential diagnosis of this unusual neoplasm from malignant melanoma and poorly differentiated carcinoma is discussed.

Heterogeneity of malignant schwannomas

Six malignant schwannomas were studied by electron microscopy and immunohistochemistry for S-100 protein at the light and electron microscopic levels to clarify the nature of the tumor cells. Three tumors (group A) were composed of poorly differentiated tumor cells and showed no immunoreactivity for S-100 protein. One tumor (group B) was composed of perineurial cells that were S-100 protein-negative. Two tumors (group C) consisted of both Schwann cells and fibroblastic cells like neurofibromas, and only the former were found to contain S-100 protein. Thus, this study showed the heterogeneous nature of the malignant schwannomas and suggested that these tumors might arise from multipotential Schwann cells or different cellular components of peripheral nerve or primitive cells.

Malignant epithelioid peripheral nerve sheath tumor arising in a benign schwannoma

The case of a patient with malignant degeneration of a solitary abdominal schwannoma and endobronchial metastasis is presented. The patient presented clinically with dyspnea referable to her lung mass, anorexia, and night sweats. The lung mass, initially diagnosed as a large-cell undifferentiated carcinoma, was later found to be histologically identical to the malignant portion of the abdominal tumor. The light microscopic, electron microscopic, and immunoperoxidase staining characteristics of the tumor are reported, and previous reports in the literature are reviewed.

Benign plexiform (multinodular) schwannoma: a rare tumour unassociated with neurofibromatosis

In reviewing a large series of soft tissue tumours, seven cases of benign plexiform schwannoma have been retrieved. These were solitary lesions, not associated with von Recklinghausen's neurofibromatosis, which arose in the dermis or subcutaneous tissue, predominantly in young adults. None has recurred. While the schwannomatous nature of these rare lesions is readily appreciated, the frequent presence of nuclear pleomorphism and the plexiform growth pattern should not be regarded as having sinister prognostic significance.

Incidence of soft-tissue cancers in blacks and whites in New York State

Incidence rates for several histologic types of soft-tissue cancers were compared between black and white residents of New York State during 1976-81, using data from the population-based New York State Cancer Registry. Incidence rates for leiomyosarcoma, neurofibrosarcoma and malignant neurolemmoma were higher for blacks than for whites in almost all age groups. Black-white differences in malignant mesenchymoma, while not statistically significant, were similar to those from other population-based studies. There was no evidence for black-white differences in certain other histologic types (e.g., blood-vessel cancers, lymphangiosarcoma). Black-white differences in leiomyosarcoma included higher rates for the uterus in black than in white females, and higher rates for the stomach in blacks of both sexes. Possible explanations for these differences in soft-tissue cancer incidence were discussed, along with comparisons with limited data on black populations in Africa.