Tumor maligno de la vaina del nervio periférico del mediastino en un paciente con neurofibromatosis tipo 1 / Mediastinal malignant peripheral nerve sheath tumor in a neurofibromatosis type 1 patient

El tumor maligno de la vaina del nervio periférico (TMVNP), es una neoplasia maligna originada en las células de Schwan de la vaina de revestimiento del nervio periférico. Describir el caso de un hombre con neurofibromatosis tipo 1 (NF1), quién presentó un TMVNP de bajo grado, y realizar una discusión sobre esta enfermedad. Hombre de 28 años, con antecedente de NF1 diagnosticada a los 15 años de edad, con dolor pleurítico izquierdo, disnea y pérdida de peso de 10 meses de evolución. Al examen de tórax, se observó marcada hipercifosis dorsal con disminución del murmullo pulmonar. La radiografía de tórax y tomografía axial computarizada (TAC), evidenciaron gran masa radioopaca bien delimitada en mediastino posterior. Por lo anterior, se realizo biopsia por punción con aguja gruesa guiada por TAC, en la cual se identificó una neoplasia maligna mesenquimal. Se decidió realizar resección del tumor a través de toracotomía posterolateral, en la que se obtuvo gran masa de 8x9x9 cm, de superficie externa irregular, pardo-violácea y consistencia firme. El estudio histopatologico e inmunofenotípico concluyo el diagnóstico de TMVNP en mediastino posterior Grado 1. Posterior a la cirugía, el paciente se encuentra asintomático. Se presentó un caso de TMVNP originado en un paciente con NF1, presentación que generalmente cursa con peor pronóstico, además se realizo una breve revisión de los aspectos más relevantes de esta enfermedad, algunos de los cuales han tenido un avance vertiginoso en años recientes.

The malignant peripheral nerve sheath tumor (MPNST) is a malignant neoplasm originated in the Schwan cells of the periferic nerves sheath. We describe a case of a man with Neurofibroatosis Type 1 (NF1), who developed a low grade MPNST, and subsequent to a discussion of this disease. 28-year-old Man with pleuritic pain in the left hemithorax, dyspnea and weight loss, with a previous diagnosis of NF1, from the age of 15 and a family history of NF1. At chest examination the patient had an intense thoracic kyphosis, with a decline in the ventilation of the inferior two thirds of the left hemithorax, where a dull sound to percusión was also found. The chest X rays showed a large radiopaque and well delimited mass in the posterior mediastinum, that pushed the cardiovascular structures to the anterior region, which was also documented by chest computed tomography (CT). In view of the above, a puncture biopsy was performed with thick needle guided by CT, from where a malignant mesenhymal neoplasm was identified. It was decided to perform the resection of the tumor of the left posterior mediastinum, by left posterior lateral thoracotomy, in which a large mass of 8x9x9 cm was obtanied, with irregular external surface, brown-violet, and firm. The histopathological and inmunophenotypic study concluded the diagnosis of MPNST in the posterior mediastinum grade 1. Following surgery the patient was asymptomatic. We present a case of MPNST which originated in a patient with NF1, who would usually have a worse prognosis. A brief review of the more relevant aspects of this disease was also reported, some of which have shown important progress in recent years.

Multicentric fibromyxoid peripheral nerve sheath tumor (multicentric schwannoma) in a dromedary camel (Camelus dromedarius): morphopathological, immunohistochemical, and electron microscopic studies.

During postslaughter inspection of a 4-year-old male dromedary camel (Camelus dromedarius), numerous small nodules to large masses up to 4 cm in diameter were found on the serosal surfaces of forestomachs, large intestines, mesentery, liver, and spleen. Grossly, the masses were discrete, round, smooth, and white to gray that bulged from the serosal layer. Cut surfaces of the masses were discrete, round, white, and relatively homogeneous without any necrotic foci. Histopathologically, the masses were encapsulated and composed of a mixture of round and spindle-shaped cells in loose whorls of neoplastic cells with small elongated hyperchromatic wavy nuclei and a small amount of pale eosinophilic, poorly defined cytoplasm. Masson's trichrome staining showed mild amounts of collagen fibers forming an irregular, loose stroma. In immunohistochemistry, immunoreactivity for the Schwann cell marker (S100) was diffusely positive in the neoplastic cells. The immunoreactivity for CK, c-kit, and CD34 were negative. Ultrastructural examination confirmed the tumor was entirely formed of neoplastic Schwann cells. On the basis of the histopathological, immunohistochemical, and ultrastructural findings, the tumors were diagnosed as multicentric fibromyxoid peripheral nerve sheath tumor (multicentric schwannoma). This tumor has not been previously recorded in camel worldwide.

Hybrid peripheral nerve sheath tumor of the nasal cavity showing schwannomatous, neurofibromatous, and perineuriomatous areas.

Soft tissue hybrid peripheral nerve sheath tumors (PNST), including schwannoma-perineurioma or neurofibroma-perineurioma, have recently been described. However, there are no reports on hybrid PNST arising in the nasopharyngeal area. In this article, we report such a case. A 58-year-old Japanese man presented with nasal obstruction and was found to have bilateral polypoid lesions in the middle meatus of the nose. Subsequently, nasal polypectomy was performed. Histologically, the tumor consisted of three components including schwannoma, neurofibroma, and perineurioma. Immunohistochemically, schwannoma, neurofibroma, and perineurioma components were positive for S-100 protein, CD34, and epithelial membrane antigen, respectively. In conclusion, this is the first case of hybrid PNST reported to occur in the nasopharyngeal area. Pathologists should be aware of the possibility that hybrid PNST may present outside soft tissue.

[Extracranial meningioma: morphological and histogenetical aspects and relations with perineurioma].

The clinicomorphological, immunohistochemical, and ultrastructural characteristics of 11 cases of extracranial meningioma versus 79 soft tissue perineuriomas were studied. There were significant similarities (cell morphology, immunoprofile, ultrastructural features of perineurial differentiation) of both entities. Considering the point of view that arachnoid and perineurial cells are anatomically, embryologically, and functionally related, it is most possible that extracranial meningiomas may be derived from perineurial cells (or their progenitor cell) rather than from displaced arachnoid cells.

An atypical peripheral nerve sheath tumour with pseudoglandular architecture in a dog.

This case describes a subcutaneous soft tissue tumour in a German Shepherd dog. Histologically, the lesion was characterized by proliferating ovoid cells, loosely arranged in a collagenous to myxoid stroma, and by numerous pseudoglandular structures lined by neoplastic cells. Immunohistochemically, neoplastic cells were labelled with vimentin, glial fibrillary acidic protein and S100 antibodies, but not with cytokeratin, desmin and smooth muscle actin antibodies. Ultrastructurally, neoplastic cells were characterized by numerous mitochondria surrounded by endoplasmic reticulum and contained few secondary lysosomes. This tumour was diagnosed as a subcutaneous peripheral nerve sheath tumour (PNST) with pseudoglandular architecture. This case illustrates the morphological diversity of PNST and provides new insight into the differential diagnosis of cutaneous tumours of similar morphology in the dog.

Malignant peripheral nerve sheath tumor of the uterine cervix expressing both S-100 protein and HMB-45.

A 50-year-old woman presented with a large cervical polypoid mass. Grossly, the mass occupied a substantial proportion of the cervical canal, measuring 6 cm. Histologically, the mass showed a spindle cell malignancy arranged in large fascicles that penetrated deeply into the fibromuscular wall of the cervix. The spindle cells were immunoreactive for both S-100 protein and HMB-45 antigen, but were negative for Melan-A. Electron microscopy showed that cytoplasmic processes of the spindle to oval tumor cells contained microtubules and were lined by basal lamina and abundant intercellular collagen spacing with no melanosomes in any stage. As far as we are aware, this is the ninth reported case of cervical malignant peripheral nerve sheath tumor (MPNST), and the second reported case of MPNST expressing HMB-45 antigen.

Diffusion-weighted imaging of retroperitoneal malignant peripheral nerve sheath tumor in a patient with neurofibromatosis type 1.

We present the diffusion-weighted imaging (DWI) findings for a malignant peripheral nerve sheath tumor arising in a retroperitoneal plexiform neurofibroma in a patient with neurofibromatosis type 1. Signal intensity of the malignant area was high on DWI and low on the apparent diffusion coefficient map and differed from findings for the benign area. DWI enabled clear differentiation between malignant and benign areas of the tumor.

Description of a neural sheath tumor of the trigeminal nerve: immunohistochemical and electron microscopy study

CONTEXT: Malignant neural sheath tumors of the trigeminal nerve affecting the nasal cavity and the paranasal sinuses are extremely rare. With conventional optical microscopy, their identification is difficult, and it is necessary to confirm them by means of electron microscopy and immunohistochemical techniques. CASE REPORT: The patient was a 41-year-old woman with a ten-month progressive history of pain followed by painful edema in the left facial region, and with symptoms of bleeding, secretion and nasal obstruction. Studies with imaging methods suggested the presence of an expansive process in the left nasal and paranasal cavities. In the biopsy, the histopathological findings from optical microscopy were suggestive of a tumor of neural origin in the trigeminal nerve. Immunohistochemical and electron microscopy studies confirmed that it was a malignant tumor of the neural sheath of the trigeminal nerve. We describe the clinical, radiological, and histological features of this tumor and review the literature.

CONTEXTO: O tumor maligno da bainha neural do trigêmeo que acomete a cavidade nasal e os seios paranasais é extremamente raro. A microscopia óptica habitual sua identificação é difícil, sendo necessária a confirmação através de microscopia eletrônica e de técnicas imunoistoquímicas. RELATO DE CASO: A paciente era uma mulher de 41 anos com história de 10 meses de progressiva dor seguida de edema álgico em região facial à esquerda, e de sintomas de sangramento, secreção e obstrução nasal. Estudos com métodos de imagem sugeriam a presença de processo expansivo em cavidades nasais e paranasais à esquerda. A biopsia, os achados histopatológicos à microscopia óptica foram sugestivos de tumor de origem neural no trigêmeo. Estudos imunoistoquímico e por microscopia eletrônica confirmaram se tratar de neoplasia maligna da bainha neural do trigêmeo. Descrevemos as características clínicas, radiológicas e histológicas deste tumor, e revisamos a literatura.

Benign schwannoma with perineurioma-like areas: A clinicopathologic study of 11 cases.

Eleven schwannomas are described. All tumors were well demarcated and surrounded by a true capsule or pseudocapsule and manifested Antoni A and Antoni B areas, Verocay bodies, and hyalinized vessels. In addition to typical schwannoma, there were clear cell areas composed of spindled cells arranged either in parallel sheets or in loops within the myxoid matrix, morphologically identical to retiform (reticular) perineurioma. The Schwann cells in the conventional schwannomatous areas displayed typical ultrastructural features. Those comprising the perineurioma-like areas revealed a primitive morphology. They were slender or polygonal and were devoid of an external lamina, pinocytic vesicles, or junctions. These findings suggest that the perineurioma-like areas consist of primitive or modified Schwann cells, or, alternatively, these perineurioma-like areas represent true, but incomplete perineurial differentiation within otherwise ordinary benign schwannomas. These neoplasms represent a morphologic variant of schwannoma having distinctive perineurial-like areas, a pattern which may elicit diagnostic difficulties.

[Ganglioneuroblastoma in Yemenite chameleon (Chamaeleo calyptratus): the first recorded case of a tumor of neuroectodermal histogenesis in reptiles].

Nerve tissue tumors are rarely encountered in reptiles and mainly represented by some documented cases of malignant peripheral nerve sheath tumor (MPNST). The paper is the first to describe a tumor mimicking MPNST by some ultrastructural features of tumor cells; however, significantly differing in the combination of immunohistochemical characteristics. Based on the data of electronic microscopy, immunohistochemistry, cytology, and histology, the tumor was classified as ganglioneuroblastoma. Since this nosological entity, unlike MPNST, cannot be assigned to a group of sarcomatoid tumors, the described pathology should be regarded as the first registered case of neuroectodermal histogenesis of tumors in reptiles.

Description of a neural sheath tumor of the trigeminal nerve: immunohistochemical and electron microscopy study.

CONTEXT: Malignant neural sheath tumors of the trigeminal nerve affecting the nasal cavity and the paranasal sinuses are extremely rare. With conventional optical microscopy, their identification is difficult, and it is necessary to confirm them by means of electron microscopy and immunohistochemical techniques. CASE REPORT: The patient was a 41-year-old woman with a ten-month progressive history of pain followed by painful edema in the left facial region, and with symptoms of bleeding, secretion and nasal obstruction. Studies with imaging methods suggested the presence of an expansive process in the left nasal and paranasal cavities. In the biopsy, the histopathological findings from optical microscopy were suggestive of a tumor of neural origin in the trigeminal nerve. Immunohistochemical and electron microscopy studies confirmed that it was a malignant tumor of the neural sheath of the trigeminal nerve. We describe the clinical, radiological, and histological features of this tumor and review the literature.

[Perineuriomas and other tumors with perineurial differentiation].

This is a review of the literature on the peripheral nerve sheath tumors with perineural differentiation. The authors provide an overview of the clinicopathological, immunohistochemical, ultrastructural, and genetic features of these neoplasms. Emphasis is laid on various morphological variants of perineurioma (intraneural, retifrm, sclerosing, plexiform, atypical, malignant, etc.) and so-called hybrid tumors (schwannoma-perineurioma, neurofibroma-perineurioma).

Intestinal perineuriomas: clinicopathologic definition of a new anatomic subset in a series of 10 cases.

Benign peripheral nerve sheath tumors are uncommon in the gastrointestinal tract, and perineuriomas have not previously been reported to occur at this anatomic location. In this study, we analyzed the clinicopathologic and immunohistochemical features of 10 perineuriomas arising in the intestine. Eight patients were female and 2 male (median age, 51 years; range, 35-72 years). Eight of the lesions were intramucosal perineuriomas presenting as small sessile polyps detected during colonoscopy; 6 of these 8 patients were asymptomatic and undergoing colorectal cancer screening. The remaining 2 cases were submucosal masses, one each located in the colon and jejunum. Of the mucosal polyps, six were located in the rectosigmoid or sigmoid colon and one each was detected in the descending colon and transverse colon. The polyps ranged from 0.2 to 0.6 cm (median, 0.4 cm) in greatest dimension. The colonic and jejunal masses measured 3 cm and 4.5 cm, respectively. Histologically, the intramucosal perineuriomas were composed of uniform bland spindle cells having ovoid to elongated nuclei and pale indistinct cytoplasm, with no cytologic atypia, pleomorphism, or mitotic activity. The lesions had a fine collagenous stroma, demonstrated irregular borders with the adjacent lamina propria, and entrapped colonic crypts. Five cases exhibited hyperplastic changes in the adjacent or entrapped epithelium. The colonic submucosal tumor was microscopically well circumscribed, whereas the jejunal perineurioma showed focal infiltration through the muscularis propria into the subserosa. The stroma was collagenous in the colonic tumor and predominantly myxoid in the jejunal tumor. The spindle cells in the submucosal perineuriomas demonstrated tapered nuclei and elongated bipolar cytoplasmic processes. All tumors except one were positive for epithelial membrane antigen (EMA); 4 of 10 expressed claudin-1 and 2 of 10 expressed CD34. All tumors were negative for S-100 protein, glial fibrillary acidic protein, neurofilament protein, smooth muscle actin, desmin, caldesmon, KIT, and pan-keratin. Electron microscopy was performed on the tumor lacking EMA expression, revealing typical features of perineurioma, namely, spindle cells with long bipolar cytoplasmic processes and prominent pinocytotic vesicles, surrounded by discontinuous basal lamina. Clinical follow-up was available for 4 patients (median, 34 months; range, 8-53 months). No tumor recurred. In summary, perineuriomas may arise in the intestine, most often as intramucosal lesions detected as colorectal polyps with distinctive histologic features including entrapment of colonic crypts. Distinguishing perineuriomas from other spindle cell neoplasms of the gastrointestinal tract can be facilitated by immunostaining for EMA and claudin-1.

Multiple perineuriomas in chicken (Gallus gallus domesticus).

Intraneural perineurioma is an extremely rare condition characterized by perineurial cell proliferation within peripheral nerve (PN) sheaths. In the veterinary field, this entity has been reported only in a dog. We examined multiple enlargements of PNs in 11 chickens (Gallus gallus domesticus) (9 Japanese bantams and 2 specific pathogen-free White Leghorn), which were inoculated with an avian leukosis virus (ALV) causing so-called fowl glioma. All chickens clinically exhibited progressive leg paralysis. Lumbosacral plexus, brachial plexus, and/or spinal ganglion were commonly affected, and these nerves contained a diffuse proliferation of spindle cells arranged concentrically in characteristic onion bulb-like structures surrounded by residual axons and myelin sheaths. The spindle cells were immunohistochemically negative for S-100alpha/beta protein. Electron microscopy revealed that these cells were characterized by short bipolar cytoplasmic processes, occasional cytoplasmic pinocytotic vesicles, and discontinuous basal laminae. These features are consistent with those of intraneural perineurioma. Furthermore, the specific sequence of the ALV was detected in the PN lesions of 8/11 (73%) birds by polymerase chain reaction. These results indicate that the multiple intraneural perineuriomas of chicken may be associated with the ALV-A causing fowl glioma.

Comparative ultrastructural and immunohistochemical study of perineurioma and neurofibroma of the oral mucosa.

In the course of assessing the cellular composition of intraoral neurofibroma (NF), we encountered a unique gingival tumor of putative perineurial (PN) origin. The lesion showed the ordinary light microscopic NF pattern, but the ultrastructural features of well-differentiated PN cells as well as an epithelial membrane antigen (EMA)-positive, S-100 protein-negative immunoprofile confirmed the diagnosis of soft tissue perineurioma (STP). In our small series of NF, there were three ultrastructural subtypes: Type I (common Schwann cell type), Type II (NF with a high content of PN cells) and Type III (predominantly fibroblastic NF), although inhomogeneous and overlapping assembly of cellular elements. A significant number of tumor cells in Type II showed the substantial reactivity for EMA, whereas many CD34-positive cells were noted in Type III. The present results confirm previous findings that PN lineage is an important constituent in the formation of NF and reinforce the value of electron microscopy in the diagnosis of peripheral nerve sheath tumors.

Malignant peripheral nerve sheath tumor of the thyroid: a clinicopathological and ultrastructural study of one case.

Thyroid malignant peripheral nerve sheath tumors (TMPNST) are very uncommon neoplasms that can be confused with anaplastic carcinoma, Riedel's thyroiditis, or other soft tissue tumors that may occur in the thyroid region. An example of TMPNST is presented in this report. The tumor occurred in a 56-yr-old woman. Fine needle aspiration did not provide adequate material. After thyroidectomy, the lesion posed important problems in differential diagnosis. Immunohistochemical, molecular, and electron microscopic features were taken into consideration to arrive at the correct diagnosis. Tumor cells were focally positive for keratins, a feature that has not been described in peripheral nerve sheath tumors of the thyroid, but that has been occasionally seen in tumors from other locations. After thyroidectomy, the patient received radiotherapy. She is well without evidence of recurrence 10 mo after surgery.

Intraneural perineurioma involving the ulnar nerve.

Intraneural perineurioma is a rare peripheral nerve sheath tumor consisting of intraneural proliferation of neoplastic perineurial cells. Clinical and pathological findings of a perineurioma involving the ulnar nerve is presented. A 7-year-old girl presented with a 2 year history of weakness and atrophy of the right hand muscles. Physical examination and imaging study revealed a pea-sized tumor in the ulnar side of the right forearm. At surgery, a fusiform swelling of the ulnar nerve was found and an excisional biopsy of the lesion was performed. Light microscopy revealed numerous whorls consisting of concentric layers of spindle cells encircling the nerve fibers. The proliferating cells were immunoreactive for vimentin, epithelial membrane antigen and glucose transporter protein 1 (Glut1), but negative for S-100 protein and CD34. Ultrastructural examination revealed features of perineurial cell differentiation. The current study suggests that Glut1 is a useful marker of intraneural perineurioma.