Search

Spindle cell lipoma (SCL), also called as pleomorphic adenoma, is a rare variant of lipoma histopathologically characterized by an admixture of mature fat cells with spindle cells and occasionally mast cells with myxoid connective tissue stroma and thick bends of birefringent collagen. Although buccal mucosa is the most common location for oral lipomas, for SCL, it is an exceedingly rare location. We report a case of an asymptomatic swelling of buccal mucosa that simulated the features of neurofibroma on histopathological examination, and the final diagnosis of SCL was made on the basis of immunohistochemical features. This is the first documentation of oral SCL using SOX10 to achieve the final diagnosis., Competing Interests: There is no conflict of interest

A pregnant patient presented with symptomatic ventricular tachycardia. Echocardiography revealed a large intramyocardial mass. Surgical resection was attempted in conjunction with cryoablation of the surrounding myocardial tissue. Histologic examination of the resected mass revealed cardiac neurofibroma. To the best of our knowledge, this is the first report of cardiac neurofibroma in a pregnant patient in the absence of any neurocutaneous syndromes such as neurofibromatosis., (Copyright © 2016 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)

Development of malignant peripheral nerve sheath tumors (MPNSTs) is a stepwise process that involves the alteration of many cell cycle regulators and the double inactivation of the NF1 gene. Inactivation of the TP53 gene and deletion of the CDKN2A/p16 gene are known to play an important role in the process. Herein, we present a 19-year-old man with a familial history of neurofibromatosis type 1, in whom the tumor arose from the intercostal nerve and showed 3 components: a neurofibroma, a low-grade MPNST, and a high-grade MPNST. Loss of p16 expression and homozygous deletion of the CDKN2A/p16 gene were observed in both the low-grade and the high-grade MPNST. In contrast to low-grade MPNSTs, high-grade MPNSTs generally tend to lose expression of p16 and harbor homozygous deletion of the CDKN2A/p16 gene. Loss of p16 expression and homozygous deletion of the CDKN2A/p16 gene in low-grade MPNST in our case might be related to its progression to high-grade MPNST. To the best of our knowledge, this is the first study correlating the p16 expression status and CDKN2A/p16 gene alteration in low-grade MPNSTs.

Background: Synovial sarcoma is a mesenchymal neoplasm that accounts for around 10% of all soft tissue sarcomas. The diagnosis of synovial sarcoma can be a challenging task, particularly with small biopsy specimens., Aim: We investigated transducer-like enhancer of split 1 (TLE1), monoclonal antibody, expression by immunohistochemical analysis in a group of 74 synovial sarcoma cases, 20 cases of MPNST, 12 cases of neurofibroma, 15 cases of schwannoma, 5 cases of MFH, 10 cases of lieomyosarcoma and 10 cases of solitary fibrous tumor., Materials and Methods: Whole tissue sections were examined: (39 biphasic and 35 monophasic). Nuclear immunoreactivity was scored as negative (<5% of cells positive), 1+(mild /5-25%), 2+ (moderate/25-50%), and 3+ (strong >50%)., Results: Overall, 71 (96%) of 74 synovial sarcomas were positive for TLE1, including 37 biphasic (95%) and 34 monophasic (97%) tumors. Other spindle cell tumors showed very low or absent staining of TLE1., Conclusions: We conclude that TLE1 is a sensitive marker and can be a useful diagnostic marker for synovial sarcoma, particularly the monophasic forms.

Unlabelled: Neurofibromas are benign nerve sheath tumours. They occur sporadically, singly or few in number, and in neurofibromatosis type 1 (NF1), an autosomal inherited disease. These tumours are composed of different cell types, e.g. nerve cells (axons and axon sheaths), Schwann cells, mast cells, and fibroblasts. The local control of tumour growth in NF1 is poorly understood. Identification of cell markers could provide new information on the processes that are involved in tumour growth., Materials and Methods: NF1 patients were diagnosed according to the revised NF1 diagnostic criteria proposed by the US National Institute of Health. Fifteen cutaneous neurofibromas from eight patients (origin: trunk and face) were excised, immediately immersion-fixed in Bouin's fixative and embedded in paraffin. Six micrometre thin sections were incubated with a variety of neuronal markers, connective tissue and glial cell markers, neurotrophic factors and their receptors. In addition, material was fixed, embedded and further processed for light and electron microscopic studies., Results: The tumours were composed of different cell types, e.g. nerve cells (axons and axon sheaths), Schwann cells, mast cells, compartmentalising cells and fibroblasts. Neuronal markers were identified in axons (neuron-specific protein gene product 9.5, PGP9.5), in several cell types (neurofilament protein-200 kDa, NF-200) and glial cells (protein S-100, S-100). In glial cells the immunoreactivity for fibroblast surface protein (FSP) was scanty, low for cyclic 2,3-nucleotide 3'-phosphodiesterase (CNPase), strong for glucose transporter 1 (Glut-1) but lacking for glial fibrillary acidic protein (GFAP). Schwann cells and so-called compartmentalising cells exhibited immunoreactivity for neurotrophin receptor protein TrkA (TrkA) and glial cell-derived neurotrophic factor (GDNF). GDNF receptor α-1 (GFR-α1) exhibited distinct immunoreactivity in single axons, in Schwann cells, and with lower intensity in some perineurial sheet cells. No immunoreactivity was observed for the low-affinity neurotrophin receptor protein p75(NTR), high-affinity receptor protein TrkB (TrkB), high-affinity receptor protein TrkC (TrkC), the neurotrophin 3 (NT-3), and the brain-derived neurotrophic factor (BDNF)., Conclusion: Human cutaneous neurofibromas displayed a pattern of neurotrophic factors and their receptor immunoreactivity, which is characteristic of differentiated non-malignant tumours, and exhibited some differences from that established in developing and differentiated control Schwann cells (probably involved in the pathogenesis of the neurofibromas), as well as tumour cells in the process of differentiation. Neurofibromas are highly vascularized tumours and possess activated endothelial cells and pericytes. We presume that most of the hyperplastic structural components of a neurofibroma are generated from activated pericytes and smooth muscle cells of the small tumour vessels which possess qualities of adult stem cells.

Background: Oral neurofibromas are peripheral nerve sheath tumors, similar to schwannomas. Histological variations in oral neurofibromas are relatively uncommon., Case Presentation: Here, we present a case of unique variation in the observed characteristics of a neurofibroma, with no relation to neurofibromatosis type-1 or von Recklinghausen disease of the skin. The neurofibroma was observed in the right mandibular gingiva of a 32-year-old Japanese woman. Histologically, it differed from conventional neurofibromas in that the tumor was composed of a mixture of fine fibrillary collagen in sheets and/or cords of neoplastic Schwann cells containing numerous clusters of Meissner bodies. Histologically, these bodies were in contact with neoplastic Schwann cells. The Meissner bodies were immunopositive for S-100 protein, neuron-specific enolase, and vimentin, but were negative for calretinin. CD34-positive spindle cells were observed around the Meissner bodies. No recurrence or signs of other tumors have been observed in the patient for 5 years after tumor resection., Conclusion: To the best of our knowledge, no formal descriptions of sporadic, solitary neurofibromas containing numerous Meissner bodies occurring in the oral cavity are available in literature. We believe that an uncommon proliferation of Meissner bodies, as seen in the present case, may result from aberrant differentiation of neoplastic Schwann cells.

A case of two sporadic cellular neurofibromas with atypia and one widespread hyalinization neurofibroma of the lumbar spine in a 51-year-old man without evidence of neurofibromatosis-1 is reported. Cellular neurofibroma with atypia is an unusual variant. The definite criteria for low-grade and high-grade malignant peripheral nerve sheath tumors as well as cellular neurofibroma are not well defined in the literature. The clinical significance of atypical cellular neurofibroma has rarely been systematically studied. To our knowledge, the concomitance of cellular architecture and cytologic atypia is rarely documented, and this is a rare report of atypical cellular neurofibroma. The recognition of this entity is of great importance to both pathologists and clinicians because atypical cellular neurofibroma is clever at masquerading both histologically and cytologically as a sarcoma; therefore, a precise diagnosis of this variant is essential because of the differences in treatment and clinical behavior between benignancy and malignancy. We also examined the immunohistochemical characteristics of CD34 positive cells and focal high expression of p53 up to 73% encountered in our case. To our knowledge, seldom have series or case reports elucidated this phenomenon.

Background: The hallmark of neurofibromatosis type 1 (NF1) is the development of multiple neurofibromas. Solitary neurofibroma may occur in an individual who does not have NF1, but multiple neurofibromas tend to develop only in those with NF1. It has been suggested that hormones may influence the neurofibromas of patients with NF1. The evidence that hormones may influence the growth of neurofibromas comes mainly from the observation that localised neurofibromas of patients with NF1 commonly grow during puberty and pregnancy. Because growth hormone (GH) concentrations increase during puberty, it is possible that GH influences the growth of these tumours., Aims: To investigate the presence of GH receptors (GHRs) in neurofibromas., Methods: By means of immunohistochemistry, the presence of GHRs was investigated in two groups of patients: 16 patients without NF1 with solitary neurofibromas (group A) and 10 patients with NF1 with localised neurofibromas (group B)., Results: Six of the 16 patients in group A had neurofibromas that were immunopositive for GHR, whereas nine of the 10 patients in group B were immunopositive., Conclusions: Most patients with NF1 have localised neurofibromas that express GHR. This suggests that GH may play some role in the development of localised neurofibromas in patients with NF1.

Neurofibromatosis type 1 (NF1) is a common genetic disorder characterized by multiple neurofibromas, peripheral nerve tumors containing mainly Schwann cells and fibroblasts. The NF1 gene encodes neurofibromin, a tumor suppressor postulated to function in part as a Ras GTPase-activating protein. The roles of different cell types and of elevated Ras-GTP in neurofibroma formation are unclear. To determine which neurofibroma cell type has altered Ras-GTP regulation, we developed an immunocytochemical assay for active, GTP-bound Ras. In NIH 3T3 cells, the assay detected overexpressed, constitutively activated K-, N-, and Ha-Ras and insulin-induced endogenous Ras-GTP. In dissociated neurofibroma cells from NF1 patients, Ras-GTP was elevated in Schwann cells but not fibroblasts. Twelve to 62% of tumor Schwann cells showed elevated Ras-GTP, unexpectedly revealing neurofibroma Schwann cell heterogeneity. Increased basal Ras-GTP did not correlate with increased cell proliferation. Normal human Schwann cells, however, did not demonstrate elevated basal Ras activity. Furthermore, compared with cells from wild type littermates, Ras-GTP was elevated in all mouse Nf1(-/-) Schwann cells but never in Nf1(-/-) mouse fibroblasts. Our results indicate that Ras activity is detectably increased in only some neurofibroma Schwann cells and suggest that neurofibromin is not an essential regulator of Ras activity in fibroblasts.