Tumor de vaina nerviosa periférica maligno asociado a neurofibromatosis tipo 1: informe de dos casos / Malignant peripheral nerve sheath tumors associated with neurofibromatosis type 1: report of two clinical cases

Introducción: El tumor de vaina nerviosa periférica maligno (TVNPM) es un sarcoma de alto grado de malignidad, originado de componentes de las vainas nerviosas, fibroblastos, células perineurales y células de Schwann, que se asocia a neurofibromatosis tipo 1 con un riesgo de 10 a 13 %. Casos clínicos: Se presentan dos casos de TVNPM asociado a neurofibromatosis tipo 1. El primero presentó dolor moderado sin causa aparente, además de lesión intrarraquídea en resonancia magnética nuclear, manejada quirúrgicamente en dos ocasiones. Histológicamente correspondió a lesión neurofibromatosa en transición con neoplasia maligna. El segundo se manifestó con cifoescoliosis torácica, dolor y aumento de volumen. Asociado a la deformidad, la resonancia magnética mostró tumor en la región torácica posterior (T1 a T8), que fue resecado; se identificó neoplasia sarcomatosa infiltrante, muy celular, con inmunopositividad para proteína S100 y vimentina. Conclusiones: Los TNVPM son sarcomas con alto índice de recurrencia, capaces de producir metástasis a distancia desde etapas tempranas. A pesar de la resección amplia, los pacientes descritos no sobrevivieron dado el avance y tamaño de las lesiones. Por el crecimiento progresivo de los TNVPM y la dificultad anatómica para su abordaje, deberá tenerse un control estrecho de los pacientes con neurofibromatosis tipo 1 a fin de identificar tempranamente la transformación maligna de las lesiones.

BACKGROUND: Malignant peripheral nerve sheath tumor (MPNST) is a sarcoma with a high grade of malignancy originating in the nerve sheath components, fibroblasts, perineural cells, and Schwann cells. It is associated with neurofibromatosis type 1 (NF-1) with a risk of 10-13%. CLINICAL CASES: We present two cases of NF-1-associated MPNST. The first patient presented moderate pain with no apparent cause, in addition to the presence of intraspinal lesion demonstrated by nuclear magnetic resonance imaging (NMRI), which was managed surgically on two occasions. Histologically, it corresponded to a neurofibromatosis lesion in transition with malignant neoplasm. The second case manifested with thoracic kyphoscoliosis, pain, and an increase in volume. Associated with the deformity, MRI showed a withering tumor in the posterior thoracic region (T1-T8), observing an infiltrating, cellular sarcomatous neoplasm with immunopositivity for S-100 protein and vimentin. CONCLUSIONS: MPNSTs are sarcomas with a high index of recurrence with the ability to produce distant metastasis during early stages. Despite wide resection, patients did not survive due to the advancement and size of the lesions (determining factors in the prognosis). Due to the progressive growth of MPNST and the anatomic difficulty for its approach, there should be strict surveillance of patients with NF-1 for early detection of malignant transformation in these lesions.

Malignant peripheral nerve sheath tumor of breast in patient without Von Recklinghausen's neurofibromatosis: a case report.

Malignant peripheral nerve sheath tumor (MPNST) of the breast without Von Recklinghausen's neurofibromatosis (VRN) is extremely rare. The authors report a 19 year-old woman who presented with a 12 month history of a painless mass of the left breast. Tissue biopsy was performed. The histologic diagnosis was made with immunohistochemical study in which the tumor showed positivity of vimentin, S-100 protein, neuron-specific protein(NSE), neurofilament protein(NF) and glial fibrillary acidic protein(GFAP). The patient was referred for radiation therapy after simple mastectomy.

Benign Peripheral Nerve Sheath Tumor of the Tongue

Peripheral nerve sheath tumors rarely occur in the oral cavity and include neurofibroma, schwannoma, and palisaded encapsulated neuroma. We report a rare case of benign peripheral nerve sheath tumor of the tongue. This tumor was a 0.8 x 0.5 cm sized, firm mass on the left lateral surface of the tongue. Histologically, this mass was composed of well- circumscribed variable sized nodules, which consisted of moderately cellular spindle cells with vague nuclear palisading and a small amount of fibrous tissue. Most of the tumor cells were strongly positive for S-100 protein, but negative for epithelial membrane antigen on immunohistochemistry. No axons were found by immunostaining for neurofilament and Bodian stains. In addition, the surrounding, compressed, fibrous tissue showed rare EMA- positive cells. The present case might be a rare case of neurofibroma arising in the tongue, although immunohistochemical and special stains did not support such a diagnosis.

Plexiform malignant peripheral nerve sheath tumor(MPNST) in infancy and childhood: a case report

We present a congenital plexiform cellular tumor with high mitotic activities arising in the right thigh of a 3-days-old infant. This subcutaneous tumor measured 6.5 x 4.5 cm in diameter with multinodular, whitish, elastic cut surface. Microscopically, the tumor was composed of fascicles of closely packed uniform spindle cells with frequent nuclear palisadings. The most remarkable finding was frequent mitoses(4-5/10 HPF). The tumor cells were strongly positive for S-100 protein, myelin basic protein and vimentin, and weakly positive for Leu 7. On electron microscopic examination, the spindle cells were found to be surrounded by continuous basal lamina and had interlocking long cytoplasmic processes. Although the prognosis of this tumor is difficult to predict, aggressive behavior such as recurrences may be suggested, but it is less likely to be metastatic. Further accumulation of similar unusual cases may be helpful in evaluation of its biologic behavior.