1/34. Unusually differentiating immature nerve sheath myxoma in association with dermal melanocytosis. A 44-year-old woman presented with a slightly elevated, erythematous lesion, with partially blue-black areas. The nonpigmented area histologically showed a "dissecting" fascicular growth pattern, similar to one of the patterns seen in the cellular type of nerve sheath myxoma. The clinically pigmented part of the lesion consisted of diffusely infiltrating, broad and poorly delineated fascicles often showing nerve sheath differentiation, embedded in a highly myxomatous stroma. No part of the lesion showed the plexiform pattern typical of the classic type of nerve sheath myxoma; rather, the lesion had some common features of neurofibroma, and also was characteristically associated with a considerable number of scattered dermal melanocytes. However, based on the fascicular histologic pattern showing nerve sheath differentiation within mucinous matrix, S-100 protein-negative immunophenotype, and electron microscopic features, we considered the whole lesion in the present case to be an entity within the spectrum of nerve sheath myxoma, either mixed-type nerve sheath myxoma or unusually differentiating immature nerve sheath myxoma, except for the associated dermal melanocytosis. Because of the intimate association of the dermal melanocytes with this nerve sheath myxoma with divergent differentiation, this lesion can also be considered as a distinctive type of benign neoplasm derived from pluripotent neural crest cells. ( info) |
| Neurothekeomas are benign tumours mostly arising in the face and upper limbs predominantly in young women. Histologically they can be classified as cellular or myxoid, and complete surgical resection is the treatment of choice. In this case of a neurothekeoma located in the anterior tongue of a child, cryotherapy was used as the treatment modality, in order to avoid a greater loss of tongue function. ( info) |
3/34. Cellular neurothekeoma with possible neuroendocrine differentiation. We report a case of cellular neurothekeoma showing unusual immunohistochemical findings and occurring on the left upper arm of a healthy 48-year-old woman. She presented with a 1 cm, red, asymptomatic, dermal nodule of 1 year duration. A biopsy showed dermal proliferation of plexiform fascicles of spindle-shaped or polygonal cells with plentiful eosinophilic cytoplasms. The immunohistochemical profile included negative stains for S-100, CD34, factor xiiia, CD68, HMB45, cytokeratins, and EMA, strongly positive stains for neuron specific enolase (NSE), synaptophysin, and chromogranin a, and focally positive ones for NKI/C3 and alpha-smooth muscle actin. Ultrastructural analysis showed undifferentiated mesenchymal cells with cytoplasmic projections and abundant RER. Although we couldn't find any confirmative cell type in this cellular tumor, we believe that cellular neurothekeoma is predominantly composed of undifferentiated cells that can exhibit features of neuroendocrine cells in addition to fibroblastic or myofibroblastic ones, suggesting a divergent cell origin. ( info) |
4/34. neurothekeoma palpebrae: a rare nerve sheath tumor arising in the eyelid. PURPOSE: To report a case of an eyelid neurothekeoma, a rare peripheral nerve sheath tumor. methods: Case report. RESULTS: An excisional biopsy, performed on a lesion removed from the upper eyelid of a 76-year-old woman, revealed the clinical and histopathologic features of a neurothekeoma, a tumor consisting of multiple collections of spindle cells in a myxomatous background. Immunohistochemical characterization showed positivity for NK1/C3, neuron-specific enolase, and alcian blue. CONCLUSION: neurothekeoma palpebrae should be considered in the differential diagnosis of solitary nodules of the eyelids. ( info) |
| Neurothekeomas are rare, benign connective tissue tumours probably of Schwann cell origin. We report an unusual case of a neurothekeoma involving the hand. Histological examination revealed characteristic myxoid nodules with spindle shaped cells. The immunocytochemical reaction for S-100 protein and neuron-specific enolase was positive. Complete excision proved curative as the tumour was well encapsulated. ( info) |
| Nerve sheath myxoma is a benign peripheral nerve sheath tumor that rarely occurs in the oral cavity; experience with these lesions is therefore limited. The lesion described in this report appeared clinically as a gradually enlarging, painless growth arising on the tongue of a newborn girl. Microscopically, the lesion was characterized by nodules of spindle-shaped cells with abundant myxoid stroma. Immunohistochemical studies were consistent with a nerve sheath neoplasm. ( info) |
7/34. Intraoral myxoid nerve sheath tumour. A case of an intraoral myxoid nerve sheath tumour of the dorsum of the tongue in a 73-year-old Caucasian male is reported. This case describes the oldest patient with this pathology to date. Immunoperoxidase staining for neuron-specific enolase (NSE) and epithelial membrane antigen (EMA) expression demonstrated the perineural origin of the lesion. ( info) |
8/34. Cellular neurothekeoma of the oral mucosa. Cellular neurothekeoma is an unusual benign neoplasm which, despite its name, is of uncertain origin. This report describes a cellular neurothekeoma of the cheek mucosa, the first at this site. The tumour presented in a 29-year-old man as a discrete mucosal thickening. histology showed a generally well circumscribed, but unencapsulated, solid tumour which replaced the entire lamina propria and permeated between minor salivary glands and bundles of striated muscle in the submucosa. There was a sub-epithelial Grenz zone. The tumour was composed of nodules of pale, epithelioid cells separated by fascicles of spindle cells, with smaller strands and nests superficially. The nuclei were vesicular and, though mainly bland, occasionally atypical. The stroma was moderately infiltrated by mixed chronic inflammatory cells. Prominent nerves and blood vessels were seen at the periphery of the lesion, and neoplastic cells were noted within intact striated muscle fascicles. With immunohistochemistry, all the neoplastic cells strongly expressed NKI/C3, synaptophysin, neurone-specific enolase and vimentin, some expressed smooth muscle actin and PGP 9.5, but all were negative for S100, factor xiiia, CD34, CD56, CD57, CD68, chromogranin a, desmin, epithelial membrane antigen and von willebrand factor. The origin of the lesion is thus speculative. It was, however, completely excised and in 12 months there has been no recurrence. ( info) |
| neurothekeoma is a benign soft tissue tumor commonly located on the skin. In this report, a 3-year-old boy presented with restricted right eye movement and decrease in visual acuity. The patient was found to have a 6-cm neurothekeoma involving the maxillary and ethmoid sinuses. To our knowledge, this is the first reported case of neurothekeoma with involvement of the maxillary and ethmoid sinuses. This uncommon lesion should be considered as the differential diagnosis of pediatric soft tissue tumors in the head and neck region. ( info) |
10/34. Intracranial neurothekeoma--a rare parenchymal nerve sheath myxoma of the middle cranial fossa. Neurothekeomas are rare, benign nerve sheath tumors, usually arising from cutaneous nerves in the head and neck region. So far, only 4 cases of the intracranial counterpart have been reported and these were located in the posterior fossa, sellar and parasellar region. We report here the first case of neurothekeoma located deep inside the brain parenchyma. Histologically, the tumor had lobular appearance with bland morphology in spite of cellular pleomorphism, myxoid background and variable S-100 positivity, characteristics of neurothekeomas. The schwannian origin was further confirmed ultrastructurally by demonstrating basal lamina and Luse bodies. Because of its benign nature, the lesion does not need postoperative radiotherapy. Histogenesis of neurothekeoma arising in the parenchyma remains enigmatic. The probable cell of origin could be the Schwann cell or perineurial cell of the nerve twigs around the blood vessels or by extreme differentiation of the precursor cell resting in a suitable microenvironment to the schwannian phenotype. ( info) |