Perineurial cell tumor (perineurioma) with granular cells

A form of benign cutaneous tumor with perineurioma findings and with the presence of associated granular cells is described. The two cases studied consisted of whorls made up of a high number of circumferentially arranged flattened cells, with perineurial characteristics, including bipolar cell processes, pinocytotic vesicles, a basal lamina, a positive immunoreactivity for EMA, and absence of immunostaining for S-100 protein. The granular cells, enclosed within the whorls, contained densely packed vesicles, particles with an apparently solid core, as well as membrane-limited vacuoles with disintegrating cellular organelles and electron-dense amorphous material. While failing to demonstrate any immunoreactivity for EMA, the granular cells showed positivity for S-100 protein, which supports their Schwann-cell origin. Due to its morphological and immunohistochemical characteristics, this peculiar form of tumor can be considered as a perineurioma with perineurial cell whorls and granular cell changes occurring in associated Schwann cells at the center of the whorls.

Spindle-cell lesions of the mediastinum: diagnosis by fine-needle aspiration biopsy

Spindle cells seen in fine-needle aspiration biopsy (FNAB) of the mediastinal lesions can be a component of a wide variety of benign and malignant conditions. Few of these conditions, however, are described in the FNA cytopathology literature. This review discusses the cytopathologic features, differential diagnoses, and potential pitfalls of a variety of lesions with a significant component of spindle cells encountered in mediastinal FNAB. The cytopathology files from four institutions were searched for cases of mediastinal FNAB containing a spindle-cell component that was a key or predominant cytologic feature of the diagnostic specimen. The cytomorphologic features of these cases were analyzed, and their differential features are discussed. Of 196 mediastinal FNABs, 22 (11%) were lesions with significant spindle-cell component: granulomatous inflammation (four); benign nerve sheath tumor (four); thymic cyst (two); spindle-cell thymoma (two); large-cell non-Hodgkin's lymphoma with sclerosis (two); nodular sclerosing Hodgkin's disease (two); liposarcoma (two); spindle-cell squamous carcinoma possibly arising in a teratoma (one); unspecified high-grade sarcoma (one); spindle-cell malignant melanoma (one); and nonspecific fibrous tissue (one). The cytologic features of each lesion were analyzed as an aid for accurate classification. These findings were correlated with radiologic and clinical information when available. The value of ancillary studies performed on aspirated material in selected cases was also reviewed. FNA of mediastinal lesions with significant spindle-cell morphology represents an infrequent and heterogeneous group of entities that may pose significant diagnostic challenges. This review presents the salient cytopathologic features of various spindle-cell lesions of the mediastinum with particular emphasis on differential diagnosis and pitfalls. The pathologist must use caution when interpreting these lesions and ancillary studies may be of significant value in selected cases.

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.

[A case of ossifying fibromyxoid tumor]

Recently described entity: ossifying fibromyxoid tumour of soft parts is presented. Schwann cell nature of the proliferating cells was demonstrated by immunohistochemical means. This special kind of nerve sheath tumors is characterised by pathological differentiation of the cells, resulting bone and in some cases additional cartilage formation. As for biological behaviour: in spite of occasional histological evidences of malignancy, no distant metastases are to be expected. Local aggressivity and recurrences may occur, thus designation is preferable as semimalignant or according to more modern terms as low-grade malignant tumour.

Adenocarcinoma combined with malignant peripheral nerve sheath tumor of the gallbladder

Adenocarcinoma of the gallbladder combined with a malignant peripheral nerve sheath tumor (MPNST) in the gallbladder in an 81-year-old woman is reported. The resected gallbladder showed two distinct tumor components, the epithelioid type of MPNST and adenocarcinoma with areas of mucin production. Although the immediate postoperative course was uneventful, a pathologic fracture of her right upper femur developed 4 months after the cholecystectomy. The pathology was determined to be a feature of metastatic MPNST rather than of adenocarcinoma. A whole body bone scan revealed multiple metastases, including the left parietal skull, left ninth rib, seventh thoracic vertebra, and right upper third of the femur. Despite cholecystectomy and postoperative irradiation therapy, she died 6 months after diagnosis of the tumor. Without an autopsy the primary site of the MPNST was unknown. We found that the prognosis was very poor in patients with distal metastatic MPNST, especially in older patients.

Malignant peripheral nerve sheath tumour: a rare tumour and an unusual intrapericardial presentation

A 62-year-old man presented with superior vena caval obstruction and was found to have a tumour in the pericardial cavity. This was diagnosed as a Malignant Peripheral Nerve Sheath Tumour (MPNST), an uncommon sarcoma that is exceedingly rare in this location. Stigmata of von Recklinghausen's disease were absent. Antibodies to a panel of immunoreactive markers were utilised to establish the diagnosis and exclude other tumours. The utility of such an approach in this kind of situation is briefly discussed.

Renal perineurioma in childhood

Perineurioma of the kidney in a 7-year-old girl is described. The tumor in the upper pole was discovered during the evaluation of a urinary tract infection. The neoplasm measured 2.6 cm and radiographically it mimicked a nephroblastoma. The diagnosis of perineurioma was confirmed with histologic, immunohistochemical, and ultrastructural studies. These revealed findings typical of perineurioma of other locations. Histopathologically, differential diagnosis may include nephroblastoma, mesoblastic nephroma, neurofibroma, schwannoma, malignant peripheral nerve sheath tumor with perineural cell differentiation, and other benign and malignant mesenchymal tumors with spindle cell pattern. To the best of our knowledge, we report a unique renal perineurioma in a child.

Pigmented peripheral nerve sheath tumor of the oral cavity with expression of AP-2 beta and c-RET: a case report

Pigmented peripheral nerve sheath tumor of the oral cavity is a rare lesion and may be difficult to distinguish clinically from true melanocytic tumors. We report a case of pigmented peripheral nerve sheath tumor with a high degree of melanocytic differentiation and describe its histologic and ultrastructural features. Immunohistochemistry and polymerase chain reaction findings support the neural crest origin of the tumor. The clinical course of our case indicates that local recurrence may be a significant problem in pigmented peripheral nerve sheath tumor.

[Malignant non-epithelial tumors of the pancreas]

Nonepithelial malignant tumors of the pancreas are extremely rare neoplasms with a frequency of approximately 0.6%. They are always explored because of a suspected diagnosis of pancreatic carcinoma. Amongst the more than 600 primary pancreatic neoplasms in our pancreatic tumor archive only 5 neoplasms were of nonepithelial origin (one was a malignant peripheral nerve sheath tumor [MPNST], one a leiomyosarcoma, one a malignant mesothelioma, and two were peripheral neuroectodermal tumors [PNET]. The differential diagnosis includes secondary infiltration of the pancreas by mesenchymal tumors of the retroperitoneum, undifferentiated pancreatic carcinoma and, especially in the case of PNET, malignant lymphoma. Preoperative chemotherapy and down-staging can improve the operability and prognosis, especially in PNET.

Benign retroperitoneal neural sheath tumors in patients without von Recklinghausen's disease

Benign retroperitoneal neural sheath tumors in patients without von Recklinghausen's disease are quite rare and usually presented as isolated case reports. There are two types of benign neural sheath neoplasms: schwannoma and neurofibroma. Confusion exists in the nomenclature of these tumors due to the disagreement upon their cell of origin. In a collective report from two institutions, three cases with benign retroperitoneal neural sheath tumors are presented, and the histological features, diagnostic and therapeutic options are discussed.

Malignant peripheral nerve sheath tumor arising in a "de novo" ganglioneuroma: a case report and review of the literature

A case of a "de novo" ganglioneuroma showing a large area of malignant peripheral nerve sheath tumor (MPNST) is described. The tumor arose in an 11.5-year-old girl with neither stigmata nor family history of von Recklinghausen's neurofibromatosis. In addition, the patient had no previous history of a neuroblastoma or radiation therapy. This report provides new evidence that, although rare, the spontaneous development of an MPNST in a benign ganglioneuroma can occur. Immunohistochemical and electron microscopy studies supported the finding that the spindle cell component was of nerve sheath origin.

Cutaneous melanoma in patients with sarcoma

BACKGROUND

The authors became interested in an association between cutaneous melanoma and sarcoma when they reviewed their experience with other malignancies occurring in patients with a diagnosis of sarcoma.

METHODS

The authors identified 48 patients with both melanoma and bone or soft tissue sarcoma (STS) by a computer search of all sarcoma patients entered into their institution's cancer registry between 1943 and 1996 who had an additional diagnosis of melanoma. The medical records were reviewed and clinical and pathologic data collected.

RESULTS

The median age at diagnosis was 46 years for patients with melanoma and 50 years for patients with sarcoma, which was consistent with population-based data. Among patients with STS (n = 41), malignant peripheral nerve sheath tumors (MPNT) were more common in patients with both diagnoses (5 of 41; 13%) when compared with all adults with STS admitted to the study center between 1982 to date (125 of 2901; 4%; P < 0.05). Liposarcoma occurred in only 1 patient with both melanoma and STS (1 of 41; 2%), despite the fact that it was the most common histologic diagnosis in all adults with STS (625 of 2901; 22%; P < 0.001). The anatomic site of STS was more commonly visceral (11 of 41; 27%) when compared with all adults with STS (424 of 2901; 15%; P < 0.05). A positive family history of cancer was noted in 50% of the patients, and 25% of patients had a third primary tumor.

CONCLUSIONS

Although a distinct "melanoma/sarcoma" syndrome was not identified, MPNT as well as visceral sarcomas were more common than expected in this study. The authors also noted strong family histories of cancer as well as additional primary malignancies in patients with melanoma and sarcoma, suggesting a predisposition toward cancer.

Purely epithelioid malignant peripheral nerve sheath tumor of the vulva

Primary malignant peripheral nerve sheath tumors(MPNST) of the vulva are extremely rare and most of them are composed of a spindle cell component. A few cases of MPNST containing partially or purely epithelioid cells have been reported. Purely epithelioid MPNST differ from the ordinary epithelioid MPNST due to the absence of a spindle cell component. We present the first case of purely epithelioid MPNST arising in the vulva reviewing in the world literature without definite evidence of von Recklinghausen's disease or nerve involvement. The patient was a 63-year-old woman with a palpable vulvar mass, 6 x 4 x 1.5 cm in dimension, was not encapsulated but well-demarcated, ovoid and rubbery and showed pale yellow, homogeneous, fish-flesh appearance with focal cystic changes on cut surface. The histologic features consisted of solely epithelioid cells which were arranged in tight clusters or cords with solid growing pattern and focally scattered rosette-like structures. According to the immunohistochemical results, most of tumor cells were strongly positive for neuron specific enolase, and some of them were weakly positive for S-100 protein and vimentin. We considered that purely epithelioid MPNST would represent a certain degree of differentiation toward nerve or neuronal cells rather than Schwann cells.

[Perineurioma]

Perineurioma (storiform perineurial fibroma) is a rarely diagnosed benign tumour of perineurial cells. Presented tumour occurred subcutaneously in the right thigh of a 53-year-old man. It was well limited and consisted of whirl like and concentric laminar bundles of spindle and oval cells in variable local density. A storiform pattern was not present. Cells with richer cytoplasm, bland nuclei and solitary intranuclear pseudoinclusions formed focal meningioma like structures. Differential diagnosis had to distinguish benign neuronal tumours, myxoid variant of dermatofibrosarcoma protuberans and especially a "low grade" fibromyxoid sarcoma. A relevant immunohistochemical marker of perineurioma (for differential diagnosis) was the expression of epithelial membrane antigen (EMA) with negativity of S-100 protein.

MR imaging differentiation of benign and malignant peripheral nerve sheath tumors: use of the target sign

BACKGROUND

T2-weighted MR imaging of soft tissue tumors of neural origin may show round lesions with a central hypointensity and a hyperintense rim resembling a target. We define the "target sign" as a mass consisting of a solitary target, or a multicompartmental mass in which the largest component consists of multiple targets.

OBJECTIVE

The objective of this study was to determine whether the target sign can differentiate benign neurofibromas and their malignant counterparts, malignant peripheral nerve sheath tumors. Materials and methods. Preoperative T2-weighted MR images of 23 neurofibromas or malignant peripheral nerve sheath tumors were retrospectively reviewed in 16 patients, aged 3 weeks to 20 years (median 15 years), without knowledge of the pathologic diagnosis. The presence or absence of a target sign was noted.

RESULTS

The target sign was seen in all 12 neurofibromas and 1 of the 11 malignant peripheral nerve sheath tumors. Statistical analysis showed good differentiation of benign and malignant tumors using this sign (chi = 0.91).

CONCLUSION

The target sign on T2-weighted MR imaging is helpful in differentiating neurofibromas from malignant peripheral nerve sheath tumors.

Soft-tissue perineurioma. Evidence for an abnormality of chromosome 22, criteria for diagnosis, and review of the literature

Reported herein are two examples of soft-tissue perineurioma (STP), one arising in the maxillary sinus and the other in subcutaneous tissue of the thigh. Electron microscopy and immunohistochemistry were performed in both cases. Based on our findings and a critical review of the literature, STPs are generally small, well-circumscribed but not encapsulated tumors. Histologically, most STPs resemble fibroblastic tumors, being composed of elongated, wavy cells. The immunohistochemical reactivity for epithelial membrane antigen, the lack of reactivity for S-100 protein, and the presence of ultrastructural features of perineurial cells are typical of this tumor. To explore the possibility that STP, like the intraneural variety of perineurioma, exhibits an abnormality of chromosome 22, we performed fluorescence in situ hybridization with a probe specific for the M-bcr locus, which maps to the chromosome band 22q11. In both our tumors, a high percentage of nuclei having only one M-bcr signal (44 and 96%) was observed. Our findings indicated deletion of part or all of chromosome 22 and support the view that both soft-tissue and intraneural perineurioma are part of a spectrum of perineurial neoplasia.

A case of von Recklinghausen's disease with bilateral pheochromocytoma-malignant peripheral nerve sheath tumors of the adrenal and gastrointestinal autonomic nerve tumors

A 48-year-old man with neurofibromatosis type 1 presented with chest pain, paroxysmal hypertension, tachycardia, and progressive respiratory insufficiency. Clinical investigation displayed calcified tumors in the anterior mediastinum and pararenal region. Histological examination at autopsy revealed composite tumors consisting of pheochromocytoma and malignant peripheral nerve sheath tumor (MPNST) at two sites: the left adrenal gland and the region surrounding the inferior vena cava, probably corresponding to the right adrenal gland. The MPNST component showed a varied histological appearance, including hyalinized bands with polygonal cells, a cartilaginous and myxoid stroma, a hemangiopericytomatous architecture, and a fibrosarcomatous structure, which suggested osteosarcoma, chondrosarcoma, angiosarcoma, and fibrosarcoma, respectively. In addition, based on the ultrastructural findings, the gastrointestinal tract was involved with mesenchymal tumors showing neurogenic differentiation. These lesions suggest the divergent cellular differentiation of neural crest-derived cells to mesenchymal elements as well as neuroectodermal neoplasms.

Magnetic resonance imaging and histopathologic appearances of benign soft-tissue masses of the foot

Magnetic resonance imaging (MRI) is now the modality of choice for the investigation of soft-tissue tumours, providing excellent anatomic detail and soft-tissue contrast. As the availability of MRI has increased, the number of requests for studies of the foot and ankle has similarly increased. The imaging department at the authors' institution, a tertiary care teaching hospital, has a large orthopedic and podiatric referral base, and as a consequence the authors have had the opportunity to study a large variety of benign soft-tissue tumours with MRI. In this pictorial essay they review the MRI and pathological appearances of the most common benign soft-tissue tumours that occur in the foot and ankle.

Monosomy 22 in a malignant peripheral nerve sheath tumour of the kidney in childhood: a genetic link with other malignant paediatric renal neoplasms?

A recurrent malignant spindle cell neoplasm of the kidney, occurring in a 11-year-old girl and corresponding to a malignant peripheral nerve sheath tumour is reported. The neurogenic differentiation was substantiated by the presence of PGP 9.5 neurofilament and S-100 protein positivity and by the ultrastructural features. Cytogenetic analysis revealed monosomy of chromosome 22 in the tumour while the constitutional karyotype was normal. Primary malignant peripheral nerve sheath tumour of the kidney is extremely rare and should, on morphology, be differentiated from stromal predominant Wilms' tumour and clear cell sarcoma of kidney. Involvement of chromosome 22 has been described in a number of malignant renal tumours of childhood, such as Wilms' tumour (deletion), clear cell sarcoma (translocation), and rhabdoid tumour (deletion and translocation), thus suggesting common molecular mechanisms in pediatric malignant renal tumours.

Brain metastases from post-radiation malignant peripheral nerve sheath tumour

A 45-year-old female patient developed a malignant peripheral nerve sheath tumour (MPNST) arising from the left brachial plexus, ten years after regional radiation treatment for Hodgkin's disease. The clinical course was characterized by local recurrence, pulmonary and cerebral metastases with endocranic hypertension syndrome, and the death of the patient 18 months after the onset of symptoms. The tumour presented a histopathological picture of schwannoma with a high grade of malignancy. A particular feature of this case was the exceptional occurrence of the early and massive invasion of the brain.

[Malignant neoplasms of the peripheral nerve sheaths with cellular immunophenotype of perineural cells (perineural sarcoma?)]

2 cases of soft tissue malignant tumors formally related to the group of spindle cell sarcoma are described. The majority of cells expressed an epithelial membranous antigen and vimentin but were S-100 protein unreactive, i.e. had a phenotype characteristic of perineural cells. Monoclonal antibodies to 5 types of filaments protein of intermediate type, neurone specific enolase and collagen type I, II, III, IV, V were also used as well as electron microscopic investigation. Problems of differential diagnosis from schwannomas, fibrosarcomas, monophasic spindle cell "synovial sarcoma" and validity of integrating these tumors into an independent variety of malignant peripheral nerve sheath tumors are discussed.