Expression of TFE3 in Cellular and Myxoid Type of Neurothekeoma: Four Cases in Young Children and Adolescents.

Introduction: Cellular neurothekeoma is a benign tumor that mainly occurs in young children and adolescents. The aberrant expression of transcription factor E3 (TFE3) has not been reported in cellular neurothekeoma previously. Case report: We report four cellular neurothekeoma with aberrant immunohistochemical expression of TFE3 protein. The fluorescence in situ hybridization (FISH) showed no TFE3 gene rearrangement or amplification. Discussion/Conclusion: TEF3 protein expression may not be related to TFE3 gene translocation in cellular neurothekeoma. TFE3 may be a potential pitfall in diagnosis, for several malignant tumors in children also express TFE3. The aberrant expression of TFE3 may offer insights into cellular neurothekeoma etiology, and associated molecular mechanisms.

Cellular neurothekeoma occurring at the site of radiation therapy in a child with medulloblastoma.

Cellular neurothekeoma is a rare, benign cutaneous neoplasm. We report a case of cellular neurothekeoma arising on the mid-back of a 10-year-old boy within the previous radiation therapy field for medulloblastoma. Clinical features of cellular neurothekeoma in children are similar to those in adults, except that there have been no reports of local recurrence in children following surgical excision, and the presence of atypical histological features does not predict clinical behavior. Recognition of this entity in children is important to avoid misdiagnosis and overly aggressive treatments.

Multiple myxoid cellular neurothekeomas in a patient with systemic lupus erythematosus.

Cellular neurothekeoma is a cutaneous tumor with a distinctive histopathologic appearance characterized by a dermal-based multinodular proliferation of epithelioid to spindled cells. Although the tumor may show varying amounts of myxoid stroma, extensive myxoid change is uncommon. The tumor typically presents as a solitary nodule with a predilection for the head and neck and upper limbs; examples of multiple cellular neurothekeomas are decidedly rare. The present report describes a unique case of multiple myxoid cellular neurothekeomas arising in a 60-year-old female with systemic lupus erythematosus. Two papular lesions were identified involving the skin inferior to the umbilicus and the left inguinal crease. Both lesions were histopathologically similar, forming a nodular mass composed of epithelioid cells in a prominent myxoid stroma. By immunohistochemistry the lesional cells expressed NKI/C3, microphthalmia transcription factor (MiTF), and CD68, with focal staining for PGP9.5, factor XIIIa, and CD10 also observed. The tumors were negative for S-100, SOX-10, epithelial membrane antigen, desmin, smooth muscle actin, glial fibrillary acid protein, and CD34. The present case confirms that cellular neurothekeoma can present clinically as multiple lesions and can have a predominantly myxoid appearance, potentially mimicking other cutaneous myxoid lesions.

Positive MITF and NKI/C3 Expression in Cellular Neurothekeoma and Dermatofibroma.

BACKGROUND: Cellular neurothekeoma (CNT) is a benign mesenchymal tumor with uncertain cellular differentiation. Studies have found evidence of myofibroblastic differentiation and possible relation to dermatofibromas (DFs). As microphthalmia transcription factor (MITF) and NKI/C3 stains are routinely positive in CNT, we compared expression patterns of both markers in CNT and DF to assess their relationship. MATERIALS AND METHODS: We assessed cases of CNT (n=25) and DFs (n=35) for histopathologic characteristics and MITF and NKI/C3 expression. Immunostaining results were classified as negative, focally positive (<50%), and diffusely positive (>50%). At least 1 additional melanocytic marker was assessed in each case of CNT. RESULTS: Both DFs and CNTs showed a female predilection and a wide age range. Immunostaining in CNTs for MITF was positive in the vast majority (focal 68%, diffuse 24%), as was NKI/C3 (focal 72%, diffuse 24%). All DFs were MITF positive (diffuse 74%, focal 26%), and most DFs were NKI/C3 positive (focal 57%, diffuse 3%). CONCLUSION: CNT and DF share demographic, histopathologic, and immunohistochemical features, including shared expression of MITF and NKI/C3, especially cellular DF.

Atypical cellular neurothekeoma (ACN) of the elderly: case report and brief review of the literature.

Atypical cellular neurothekeoma (ACN) is an aggressive and rare variant of cellular neurothekeoma. Only few cases have been reported in the literature and the biological behavior seems to be uncertain. We describe the case of an ACN presenting on the scalp of an elderly man, emphasizing the cytologic features of malignancy. In addition, we provide a brief overview of the literature and discuss the differential diagnosis with other entities, and the possible diagnostic pitfalls.

Sleeve-Shaped Neurothekeoma of the Ulnar Nerve: A Unique Case of a Still Unclear Pathological Entity.

Background: Neurothekeomas are slow-growing, well-circumscribed benign neoplasms. They usually involve cutaneous or subcutaneous tissues. Although originally described as myxomas deriving from nerve sheath cells, their exact histological classification is still uncertain. Peripheral nerve localization is rarely reported. Here, we describe a unique case of sleeve-shaped neurothekeoma of the ulnar nerve, which was incidentally discovered during a cubital tunnel release surgery. Methods: A 57-year-old man was admitted at our institution with clinical, ultrasonographic, and electromyographic findings highly suggestive of cubital tunnel syndrome. During ulnar nerve decompression surgery, however, no bony or ligament compression was noticed, but a segment of the nerve wrapped by a thick sleeve-shaped tissue, which had no clear-cut cleavage plane from the nerve. Given this unexpected finding, the en bloc excision of the lesion was avoided. A nerve decompression with biopsy of the swelling portion of the lesion was performed instead. Results: Histological examination described abundant myxoid stroma, with epithelioid and ring-shaped cells arranged in cords, negative to S100 protein at immunohistochemical analysis. This pattern was suggestive of neurothekeoma. The patient showed improvement in hypermyotrophy and intrinsic weakness of the hand. Conclusions: To the best of our knowledge, this is the first report of a sleeve-shaped neurothekeoma of the ulnar nerve. The exact pathological characterization of such rare entities remains uncertain. In case of peripheral nerve localization, and when a clear cleavage plane is absent, the correct management of these lesions should be that of simple nerve decompression followed by biopsy.

Cellular neurothekeoma: Report of two cases with unusual immunohistochemical features.

Cellular neurothekeoma (CNT) is a dermal lesion with still unknown histogenesis, characterized by immunohistochemical staining for NKI/C3, NSE, MiTF, CD10 and CD68, whereas S100 protein, desmin and cytokeratins are negative. Particularly, in several studies NKI/C3 has been reported as a strong marker of CNT. We describe herein the clinical, histopathological and immunohistochemical features of two cases morphologically consistent with myxoid CNT, one of which showing some atypical features, both characterized by negative immunohistochemical staining for NKI/C3. Our findings stress the importance of morphology in diagnosing CNT and underline the fact that NKI/C3 can fail to stain cases belonging to the "neurothekeoma family." In selected cases of CNT, an expanded immunohistochemical panel is mandatory to differentiate this tumor from other dermal lesions.

Multiple cellular neurothekeomas in a middle-aged woman including the lower extremity: A case report and review of the current literature.

Cellular neurothekeoma is a benign cutaneous neoplasm that typically occurs on the head, neck, and upper body of young adults with a slight female predominance. It is a rare lesion to diagnose and multiple neurothekeomas in one patient are even more uncommon finding. We present a case of multiple neurothekeomas in a middle-aged woman with lower extremity involvement and summarize the current literature on multiple neurothekeoma patients. A 46-year-old female presented with nearly one dozen skin-colored papules on the head, upper limb, and lower limb. The lesions were clinically diagnosed as dermatofibromas and a nevus. Eight lesions were biopsied and confirmed to be cellular neurothekeomas, with one initially misinterpreted on histology as a dermatofibroma. Awareness of cellular neurothekeoma as a diagnostic entity and the possibility of atypical presentations as seen in our case (eg, in multiple numbers, in older adults, and on the lower extremity) are important in allowing for accurate clinical and histological diagnosis of these lesions. The possibility of a syndromic association with multiple cellular neurothekeomas should be explored further.

Atypical cellular neurothekeoma: A potential diagnostic pitfall for benign and malignant spindle cell lesions in skin.

Cellular neurothekeomas (CNTs) are rare, benign cutaneous tumors that arise primarily on the head and neck, with a slight female predominance. CNTs with atypical features have been described, including those with an infiltrative growth pattern. Although CNTs with atypical features are benign, recognition of this entity can pose diagnostic challenges. Here, we report a case of CNT with an unusual clinical presentation on the left second digit, and with atypical histological features including an infiltrative growth pattern, which could have been mistaken for features of malignancy.

Protein gene product 9.5 (PGP9.5) expression in benign cutaneous mesenchymal, histiocytic, and melanocytic lesions: comparison with cellular neurothekeoma.

Cellular neurothekeoma (CNTK) frequently enters the differential diagnosis of a benign dermal cellular proliferation. Diagnosis often relies on immunohistochemistry including the use of protein gene product 9.5 (PGP9.5). A previous study demonstrated PGP9.5 expression across a wide variety of soft tissue neoplasms. We explored the utility of this antibody in distinguishing CNTK from other benign dermal-based lesions. A cohort of CNTK (n=7) and benign cutaneous lesions of neural (n=28), fibrohistiocytic (n=23), fibroblastic (n=25), histiocytic (n=18), myofibroblastic (n=7), smooth muscle (n=14), and melanocytic (n=12) differentiations were immunostained with PGP9.5. Staining was graded by H-score and compared with CNTK. A significantly higher H-score was found in CNTK compared with the fibrohistiocytic (p=0.0001), histiocytic (p=0.0016), myofibroblastic (p=0.0003), smooth muscle (p<0.0001), and melanocytic (p=0.0004) groups, with the exceptions of plexiform fibrohistiocytic tumour, xanthoma, and xanthogranuloma. No significant difference was found when comparing CNTK with fibroblastic and neural lesions, with the exceptions of neurofibroma and perineurioma. In conclusion, PGP9.5 is helpful in distinguishing CNTK from most benign cutaneous fibrohistiocytic, histiocytic, myofibroblastic, smooth muscle, and melanocytic lesions. In addition to CNTK and neural lesions, PGP9.5 is also expressed in benign fibroblastic lesions, and therefore distinction of these lesions should not be based on PGP9.5 positivity.

Neurothekeoma in the middle cranial fossa as a rare location: Case report and literature review.

Neurothekeoma is a benign cutaneous nerve sheath tumor usually located in the head and neck region. To date, only a few cases of intracranial location have been reported in the literature. We report an extremely rare case of intracranial neurothekeoma located in the brain parenchyma of the middle cranial fossa. A 55-year-old female patient was operated on at our clinic for a right temporal cystic mass lesion with heterogenic contrast enhancement. Histologically, the tumor had a multinodular hypercellular appearance with a myxoid matrix, peripheral fibrosis, and sclerosis. It was characterized by spindle and epithelioid mononuclear cells, immunochemically positive with diffuse S-100, vimentin, GFAP, PGP 9.5, and NSE, as characteristics of cellular neurothekeomas. After a total surgical resection, there was no need for further adjuvant chemotherapy or radiotherapy. Because there were still unclear aspects regarding the origin, pathogenesis and management of the intracranial neurothekeomas, we decided to contribute to the literature with this case report.