Malignant peripheral nerve sheath tumor: a study of 21 cases

BACKGROUND

Malignant peripheral nerve sheath tumor (MPNST) is an aggressive tumor of neural origin. To improve our experience with this rare tumor, we reviewed 21 patients seen during a 12-year period at the pathological department of Taichung Veterans General Hospital.

METHODS

Clinical data including age, sex, presence or absence of von Recklinghausen's disease, tumor location and size, presenting symptoms, surgical management and surveillance were summarized. Microscopically, we examined necrosis, mitosis, differentiation, the resection margin, and the presence or absence of neurofibromatous component.

RESULTS

There were 15 males and 6 females with age range of 9-86 years. Seven cases were associated with neurofibromatosis and 14 cases were solitary MPNST: Patients with coexistent neurofibromatosis were younger (mean age at diagnosis, 32 years) than patients with solitary MPNST (mean, 60.2 years). Tumors of the former group tended to be centrally located. Anaplastic alteration was found in the recurrent tumors of two patients both of whom died of the disease. Of the 21 cases, epithelioid differentiation and osteoid metaplasia were seen in two tumors respectively by optical microscopy. Patients with von Recklinghausen's disease and large incompletely resected tumors had the most dismal prognosis. Of five patients with neurofibromatosis who were observed for more than two years, only one survived and no recurrence was found. The remaining four patients died within 3-9 months. However, of 14 cases of solitary MPNST, only two patients died of disease and ten of them had survived beyond two years.

CONCLUSIONS

Our work revealed that patients with von Recklinghausen's disease, a large unresectable centrally located tumor with diffuse anaplastic alteration, had frequent recurrences and poor prognosis. Aggressive surgical procedure with free resection margin is suggested. Malignant transformation should be highly suspected when a painful, rapidly growing tumor developed.

Benign glandular peripheral nerve sheath tumor. A case report

The glandular peripheral nerve sheath tumor is a rare variant of nerve sheath neoplasms in which the focally occurring glands are lined by cells showing divergent differentiation. The vast majority of the reported nerve sheath tumors harboring these glands have been malignant. We herein present a case of benign glandular peripheral nerve sheath tumor in a 43-year-old woman who had no evidence of von Recklinghausen's disease. Histologically, the tumor is composed of spindle cell component and collections of glandular component. The glandular component occupied the central two-thirds of the lesion and was lined by a single layer of nonciliated cuboidal or columnar cells. No mitotic figures were recognized in the spindle cell area. This spindle cell area had neurofibroma-like features rather than schwannoma. Many of the spindle cells had positive reaction products for S-100 protein. The glandular lining epithelium were positive for cytokeratins (CAM 5.2, AE1/AE3, PKK1) and EMA. Some epithelial cells were immunoreactive for CEA, chromogranin, somatostatin and Leu-7. These immunohistochemical findings support the neuroendocrine differentiation of the epithelial element from the schwannian component.

Plexiform malignant peripheral nerve sheath tumor of infancy and childhood

We present nine cases of an atypical cellular peripheral nerve sheath tumor, designated plexiform malignant peripheral nerve sheath tumor (MPNST) of infancy and childhood, occurring in five boys and four girls aged 50 days to 13 years (median, 1.5 years). The tumors were located in the lower extremities (five cases), upper extremities (three cases), and the orbital region (one case), and they ranged from 1.5 to 8 cm in size (median, 3 cm). Two lesions were congenital, and another was associated with a history of von Recklinghausen's disease. Follow-up, available in six cases, ranged from 6 months to 15 years (median, 51 months); four patients had local recurrences within 8 to 31 months after excision of the initial lesion, and one with an orbital tumor died of locally invasive disease within 6 months. Histologically, the initial lesions were characterized by a predominantly superficial location within the dermis and subcutis, with occasional extension into deeper soft tissues, had infiltrative or sharply demarcated margins, and resembled entangled or intertwined hypercellular nerve trunks, resulting in a plexiform appearance at low magnification. The nuclei were oval to serpentine with a vesicular chromatin pattern and small basophilic nucleoli; mitoses were seen in all cases and averaged from 1 to 18/10 high-power fields (hpf) (median, 4/10 hpf). Neither necrosis nor vascular invasion was seen. Features diagnostic of plexiform or cellular schwannoma, such as nuclear pleomorphism, Antoni B areas, thick-walled hyalinized blood vessels, and secondary degenerative features were lacking. Other than a prominent plexiform architecture, the lesions were indistinguishable from MPNST occurring in other sites in infants and children. Although none metastasized, the histologic similarity of plexiform MPNST to other childhood MPNST, its relatively high propensity for local recurrences, and its potential to behave in a locally aggressive manner indicate that it is best regarded as low-grade malignant. Overall, the behavior of plexiform MPNST is better than other MPNST in children, probably because of its relatively small size, peripheral and superficial location in most instances, absence of necrosis or vascular invasion, occurrence in young patients, and infrequent association with von Recklinghausen's disease rather than a function of its prominent plexiform architecture. Distinction of plexiform MPNST from cellular and plexiform schwannoma, plexiform neurofibroma, and hamartomatous lesions of childhood is important. Complete excision should be ensured to prevent local recurrences and potential metastases.

Glandular peripheral nerve sheath tumours

Glandular differentiation in peripheral nerve sheath neoplasms is a rare but well recognised phenomenon, believed to represent the least common of the various forms of heterologous differentiation which may occur in tumours of peripheral nerve. This group of tumours--the 'glandular peripheral nerve sheath neoplasms'--are the subject of this short review. The majority of glandular peripheral nerve sheath neoplasms arise in patients with von Recklinghausen's disease and follow a malignant course, but both benign and sporadic forms have now been described. Neither the presence nor the appearance of the glandular foci are believed to influence patient outcome. Predictions of likely biologic behaviour are best based upon an assessment of the nature of the accompanying spindle cell stroma. Glandular peripheral nerve sheath neoplasms must be distinguished from various tumours of soft tissue which may share similar histological features e.g. synovial sarcoma and the epitheloid nerve sheath tumours. Immunohistochemistry and ultrastructural examination may aid in this regard, and have also contributed to our understanding of the nature and origin of the glandular structures, though questions regarding their histogenic origins remain somewhat controversial.

Malignant peripheral nerve sheath tumors of the head and neck: a clinicopathological study

Twenty-seven cases of malignant peripheral nerve sheath tumors involving the head and neck region over a period of 7 years were reviewed. They were graded from 1-3 based on necrosis, mitosis, cellularity, and pleomorphism. Mean age of occurrence was 42 years, with a range of 12-70 years. Male preponderance was noted (M:F = 3.5:1). The most common site of involvement was the neck (44.6%). The main presenting symptom was an enlarging mass. The nerve of origin could be identified in 33% of patients. Treatment consisted of wide excision. The 5-year observed survival was 33%. Fifty-two percent of patients developed local recurrence of disease. Fifteen percent of patients died due to advanced local disease within 18 months of treatment. Distant metastasis was seen in 18.5% of patients. Lymph node metastasis was not seen. At the end of 5 years 15% of patients remained disease free. Large tumor size (> 5 cm) adversely affected the prognosis (P = < 0.1). No significant correlation was noted between the grade of tumor and survival.

Cell culture studies on human nerve sheath tumors

The main controversy about nerve sheath tumors (NSTs) has been their histogenesis. A Schwann cell origin has been proposed by many investigators for both schwannomas and neurofibromas. However Erlandson and Woodruff observed that while schwannomas appeared to be composed predominantly of Schwann cells, neurofibromas consisted of mainly perineurial cells. In addition, variable numbers of fibroblast-like cells and intermediate cells also have been reported in the 2 lesions. Whether these represent distinct cell types or variants of Schwann cells is still debatable. In an attempt to solve this controversy, the present study was undertaken to observe the morphology and the behaviour of these tumors in culture. These studies showed that all nerve sheath tumors are basically of Schwann cell origin and that intermediate cells and fibroblasts are variants of Schwann cell. Tissue culture studies done chiefly on schwannomas showed that the morphological features of schwannomas are preserved in 'in vitro culture' condition and therefore the difference between neurofibroma and schwannoma appears to be due to inherent differentiating property of the Schwann cells along with some environmental stimulus.

Malignant nerve sheath tumors of the head and neck: four case studies and review of the literature

Malignant peripheral nerve sheath tumors (MPNST) are very uncommon neoplasms. While the incidence of these lesions is estimated to be 0.001% in a general population, they make up 5-15% of all soft tissue sarcomas in the head and neck region. We present four cases of MPNST in the head and neck. Since certain difficulties were encountered in diagnosis, the importance of clinical evaluation is emphasized. The prognosis for these tumor patients is poor in spite of improvements in diagnostic and therapeutic modalities.

Cutaneous malignant peripheral nerve sheath tumour (MPNST) of the hand: a review of current literature

Malignant peripheral nerve sheath tumours (MPNST) are spindle cell sarcomas normally situated in the deep soft tissues. Cutaneous MPNST is an uncommon variant, usually occurring in the head and neck. When it arises in the upper limb this tumour may pose a considerable diagnostic and therapeutic problem. We present a case of cutaneous MPNST arising in the hand. Tumour extension was exclusively perineural along three major nerve trunks from an interdigital origin. Current knowledge of the clinical behaviour of cutaneous MPNST is reviewed.