Pseudoglandular schwannoma

Multiple schwannomas with pseudoglandular element synchronously occurring under the tongue: A case report

BACKGROUND

Schwannoma is a rare benign, encapsulated tumor of the nerve sheath under the tongue, mostly occurring as solitary tumors with classical histological pattern and several common morphological variants. To our knowledge, multiple schwannomas with pseudoglandular element synchronously occurring under the tongue are rare; we report herein the first such case.

CASE SUMMARY

A 53-year-old man had first noticed an isolated asymptomatic mass under the tongue, and as the mass grew, the tongue was elevated. Physical examination showed multiple oval neoplasms, and the overlying mucosa was normal. Computed tomography showed three low-density oval neoplasms under the tongue, which were cystic-solid with unclear boundary. The patient has no cutaneous tumors, VIII nerve tumors, or lens opacities and no history of neurofibromatosis 2 or confirmed schwannomatosis in any first-degree relative. Magnetic resonance imaging showed no evidence of vestibular schwannoma. The preoperative diagnosis was mucoepidermoid carcinoma. During hospitalization, all neoplasms were completely excised by surgeons through an intraoral approach under general anesthesia. The diagnosis of the multiple schwannomas with pseudoglandular element was made by histopathology after surgery. At the 15-mo follow-up visit, the patient had no sign of recurrence or development of other peripheral nerve tumors.

CONCLUSION

Although rare, multiple schwannomas with pseudoglandular element do exist in patients presenting with masses under the tongue. Oral surgeons should be aware of the existence of multiple schwannomas with pseudoglandular element when considering masses under the tongue due to the different prognosis between multiple schwannomas with pseudoglandular element and mucoepidermoid carcinoma.

Glandular Schwannoma: An Uncommon Variant of Schwannoma with Controversial Histogenesis

Schwannomas are benign, encapsulated nerve sheath tumors arising from Schwann cells; several histologic variants of schwannoma have been described, including the exceedingly rare glandular schwannoma (GS). The histogenesis of the glands in GS (as well as in other peripheral nerve sheath tumors with a glandular component) remains unclear; no consensus exists as to whether glands should be interpreted as metaplastic elements or entrapped reactive glands. We report a case of GS with detailed immunohistochemical analysis of the epithelial component. We believe that our findings raise further questions regarding the histogenesis of glands in GS, casting doubts on the traditional distinction between true metaplasia and glandular entrapment. Further research is warranted in this regard.

Neural and neurogenic tumours of the gastroenteropancreaticobiliary tract

Neural lesions occur uncommonly in the gastroenteropancreaticobiliary tract. However, due to the growing number of screening colonoscopy procedures, polypoid neural lesions of the colon are being recognised increasingly and range from benign tumours to high-grade malignant neoplasms. Morphological variability of neural tumours can be wide, although some entities share pathological features, and, as such, these lesions can be diagnostically challenging. We review the spectrum of pathology of neural tumours in the gastroenteropancreaticobiliary tract, with the goal of providing a practical approach for practising surgical pathologists.

Divergent Schwannoma-Like Phenotype in a Pleomorphic Adenoma

The schwannoma-like pleomorphic adenoma is a rare histopathological variant of the pleomorphic adenoma. Five previous reports with seven cases exist in English language literature. These tumors present in the parotid gland most commonly. Intraparotid schwannomas of the facial nerve and schwannomas with glandular differentiation have also been reported. A 60-year-old male presented with an asymptomatic swelling over the left angle of the mandible. The swelling had been present for about 12 years with a recent increase in size. CT imaging showed a hyperdense circumscribed mass of the superficial lobe of the parotid. The working diagnosis was that of a benign tumor of salivary gland or soft tissue origin. The mass was excised with careful preservation of the facial nerve. The 3.5 cm mass was submitted for histopathological examination. The well-circumscribed, encapsulated mass showed a predominant sheet-like proliferation of Antoni type A-like tissue, Foci of glandular differentiation with duct-like structures were also seen. Cytological atypia or mitotic activity were not seen. Nuclei of lesional cells diffusely and strongly expressed reactivity to p63. The final diagnosis was a schwannoma-like pleomorphic adenoma. No recurrence has been reported in the 15 months since the removal. Facial nerve function is unimpaired with a House Brackmann facial nerve function score of one. The potential for misdiagnosis in fine needle aspirate and incisional biopsies is real in cases of schwannoma-like pleomorphic adenoma. The diagnostic pitfalls include the schwannoma and leiomyoma. Schwannomas with glandular differentiation have also been reported and therefore a misdiagnosis may potentially occur in excised specimens. Careful application of immunohistochemistry may help in the differentiation of these lesions.

Benign Glandular Schwannoma With Ancient Change

Benign glandular schwannomas are rare and should be distinguished from malignant peripheral nerve sheath tumors with similar divergent tissue differentiation. The authors present a benign glandular schwannoma with ancient change that developed in the subcutis of a 46-year-old man's posterior calf. He lacked stigmata of neurofibromatosis type 1 (NF1). The glandular elements stained positively for epithelial membrane antigen and pancytokeratin. The spindled cells stained positively for SOX10 and S100 protein, supporting schwannian (neural crest) differentiation. The tumor's location and histopathology suggest that the pathogenesis stems from entrapment of sweat glands. Finally, it must be recognized that ancient change may mimic malignancy in these neoplasms as the malignant counterparts have a greater association with NF1 and a poorer prognosis.

Benign Glandular Schwannoma in Basal Ganglia

BACKGROUND

The oncogenesis and biologic behaviors of benign glandular schwannoma have not been clinically unveiled because of its rarity and variability.

CASE DESCRIPTION

However, we report a young male patient who presented with a benign glandular schwannoma in the basal ganglia, a site that has not been reported in any literature. Histologically, the samples are composed of spindle-shaped cells and variable glandular structures. The spindle-shaped cells are identified with the appearance of Antoni A and Antoni B zones. Moreover, the glandular structures are lined by stratified epithelial cells, glandular epithelium cells, intestinal epithelial cells, and few degenerative syncytial macrophage cells. Hemorrhage, necrosis and cystic changes were observed in the specimen cells, but no mitotic figures were found. The immunohistochemical results showed that the spindle cells were stained with S-100 protein, but lacked carcinoembryonic antigen (CEA), cytokeratin pan (AE1/AE3) (CK), synaptophysin, chromogranin A, and glial fibrillary acidic protein reactivity after surgery. Meanwhile, the glandular epithelium cells mostly consisted of glandular epithelium and stratified epithelium cells stained with CEA, chromogranin A, and CK antigen.

CONCLUSIONS

Therefore, the morphologic and immunohistochemical findings support the diagnosis of benign glandular schwannoma.

Schwannomas with pseudoglandular elements: clinicopathologic study of 61 cases

Schwannomas are benign neoplasms of peripheral nerve sheath. A number of morphologic variants of schwannoma have been described. The pseudoglandular variant is very rare. We retrieved and reviewed hematoxylin and eosin slides of all cases of schwannoma reported between 2007 and 2014 to look for pseudoglandular elements. Pseudoglandular cystic spaces were seen in 61 (6.3%) of 971 schwannomas diagnosed during the study period. Of these 61 cases, 56 (91.8%) were located in the spinal nerve roots. The majority (60.6%) were male. Mean age in these 61 cases was 41 years. Mean tumor size was 3.5 cm. All 61 cases showed typical Antoni A and Antoni B areas with multiple pseudoglandular cystic spaces scattered throughout. These areas were lined by flat to cuboidal cells which showed positivity for immunohistochemical stain S-100 and were negative for epithelial membrane antigen. An average of 7 pseudoglandular cystic spaces was noted per case. In conclusion, pseudoglandular cystic spaces are lined by Schwann cells and most likely represent degenerative changes in schwannoma probably degenerated Verocay bodies. They are rare albeit well-defined features seen in a significant though small number of schwannomas. It is important not to mistake them for other neoplasms. Larger studies are required to determine predilection of these changes in spinal nerve root schwannomas as seen in our series.

Neurogenic tumors of soft tissue

Neurogenic tumors are an uncommon yet important category of soft tissue tumors in children and adolescents because of their frequent association with various genetic syndromes. The heterogeneous cellular composition of the peripheral nerve and the wide metaplastic capacity of the neural crest and its derivatives generate a variety of neoplasms with neurogenic differentiation. This article reviews the clinicopathologic features and differential diagnosis of neurogenic tumors in the first two decades of life, and highlights use of selected ancillary methods for diagnosis.

Pathology of peripheral nerve sheath tumors: diagnostic overview and update on selected diagnostic problems

Peripheral nerve sheath tumors are common neoplasms, with classic identifiable features, but on occasion, they are diagnostically challenging. Although well-defined subtypes of peripheral nerve sheath tumors were described early in the history of surgical pathology, controversies regarding the classification and grading of these tumors persist. Advances in molecular biology have provided new insights into the nature of the various peripheral nerve sheath tumors, and have begun to suggest novel targeted therapeutic approaches. In this review, we discuss current concepts and problematic areas in the pathology of peripheral nerve sheath tumors. Diagnostic criteria and differential diagnosis for the major categories of nerve sheath tumors are proposed, including neurofibroma, schwannoma, and perineurioma. Diagnostically challenging variants, including plexiform, cellular and melanotic schwannomas are highlighted. A subset of these affects the childhood population, and has historically been interpreted as malignant, although current evidence and outcome data suggest they represent benign entities. The growing current literature and the author's experience with difficult to classify borderline or "hybrid tumors" are discussed and illustrated. Some of these classification gray zones occur with frequency in the gastrointestinal tract, an anatomical compartment that must always be entertained when examining these neoplasms. Other growing recent areas of interest include the heterogeneous group of pseudoneoplastic lesions involving peripheral nerve composed of mature adipose tissue and/or skeletal muscle, such as the enigmatic neuromuscular choristoma. Malignant peripheral nerve sheath tumors (MPNST) represent a diagnostically controversial group; difficulties in grading and guidelines to separate "atypical neurofibroma" from MPNST are provided. There is an increasing literature of MPNST mimics which neuropathologists must be aware of, including synovial sarcoma and ossifying fibromyxoid tumor. Finally, we discuss entities that are lacking from the section on cranial and paraspinal nerves in the current WHO classification, and that may warrant inclusion in future classifications. In summary, although the diagnosis and classification of most conventional peripheral nerve sheath tumors are relatively straightforward for the experienced observer, yet borderline and difficult-to-classify neoplasms continue to be problematic. In the current review, we attempt to provide some useful guidelines for the surgical neuropathologist to help navigate these persistent, challenging problems.

An unusual case of glandular schwannoma

Glandular differentiation is exceedingly rare in peripheral nerve sheath tumors. In this report, an exceptional case of retroperitoneal glandular schwannoma is described in which the glandular element is markedly atypical, whereas the schwannian component is benign by morphologic analysis. To the best of our knowledge, the biologic behavior for such a lesion is unknown because similar cases have not yet been described in the literature.

Pseudoglandular schwannoma of the cauda equina. Case report

The authors present a case of pseudoglandular schwannoma with immunohistochemical findings consistent with epithelial metaplasia. Pseudoglandular schwannoma is a rare morphological variant of benign schwannoma characterized by the presence of glandlike structures lined with Schwann cells. To the best of the authors' knowledge, this is only the fifth case of pseudoglandular schwannoma reported in the literature. Clinical, imaging, and pathological findings are described. The pathological findings were consistent with a pseudoglandular schwannoma composed of typical Schwann cells arranged in an Antoni B pattern, with numerous large pseudocystic spaces. Serial immunohistochemical studies of tissue sections revealed that the cells lining the pseudoglandular spaces were not only diffusely reactive for S100 protein, but also demonstrated focal positivity for epithelial membrane antigen and cytokeratins AE and AE3. The particular immunohistochemical features of incompletely differentiated Schwann cells in the present case give support to the metaplastic theory of the origin of glandlike structures in benign peripheral nerve sheath tumors.

Intraparotid pseudoglandular schwannoma

A unique intraparotid location of a rare pseudoglandular schwannoma is described. Although the diagnosis of schwannoma could readily be substantiated, accurate subtyping was initially mislabeled. The pitfall was in failing to acknowledge the presence of multiple well-formed gland-like structures, which is instantly thought to be cystically dilated salivary ducts. Immunohistochemically, epithelial-appearing cells lining the duct-like spaces proved to be schwannian in nature. Interpretation of an immediately recognizable gland-like architecture is more problematic when a pseudoglandular variant originates from a nerve coursing through the gland, as here.

Benign cutaneous pseudoglandular schwannoma: a case report

Schwannoma is a common peripheral neural neoplasm that could present as a primary skin lesion. In addition to typical schwannoma with classic Antoni A and Antoni B areas, many variant types have been described, such as plexiform, cellular, epithelioid, and ancient schwannomas. Glandular schwannoma is a rare variant characterized by the presence of glands in an otherwise typical schwannoma. There are also a few reported cases in the literature of pseudoglandular schwannoma from central nervous system, eye, submandible, and shoulder, in which the gland-like structures were lined by Schwann cells. We report here a patient with a benign cutaneous schwannoma composed of predominantly gland-like spaces that contained mucinous material and were lined by Schwann cells confirmed by immunohistochemistry and ultrastructural studies. The tumor was well circumscribed and showed minimal cytologic atypia, indicating benignity. We report this unusual case of benign cutaneous pseudoglandular schwannoma to further awareness of the morphologic diversity of schwannoma.

Pseudoglandular Elements in Schwannomas

Context.—Uncommon examples of schwannomas are seen in which a coexisting glandular component is present. The pseudoglandular schwannoma is a relatively recently described variant in which cystic spaces are lined by pseudocolumnar or cuboidal-like neoplastic Schwann cells exhibiting an epithelial-like appearance.

Objectives.—To determine the incidence of pseudoglandular elements in schwannomas, to describe the variable morphology of the schwannomas that may contain pseudoglandular elements, and to discuss the potential mechanisms of development and biological significance of these elements.

Design.—We screened 202 schwannomas from any anatomic site for the presence of pseudoglandular elements and examined these with light microscopy, immunohistochemistry, and electron microscopy.

Results.—Sixteen (7.9%) of the schwannomas contained pseudoglandular elements, which ranged from poorly to well organized in appearance and which were found in schwannomas exhibiting a wide range of morphologic appearances. The Schwann cell nature of the cells composing these elements was apparent both immunohistochemically and ultrastructurally. The frequency of proliferative activity within these elements was no greater than that observed throughout the remainder of the respective schwannomas.

Conclusions.—Our observations suggest that, rather than representing a distinct phenotypic schwannoma variant, pseudoglandular elements likely arise as a response to a degenerative phenomenon, perhaps reflecting the propensity that the Schwann cell has to palisade formation. Such elements may be found within a variety of schwannoma variants and do not appear to possess a unique growth potential.

Benign glandular schwannoma

Glandular schwannoma is a rare variant of schwannoma characterized by the presence of glands in an otherwise typical schwannoma. We report a patient with benign glandular schwannoma occurring on the scalp, a site not previously reported. Histologically, a well-defined, encapsulated oval nodule was observed in the subcutaneous tissue. The nodule was composed of a spindle cell component and glandular structures. The spindle cell component stained positively for S-100 protein. All of the glandular epithelium stained with CAM 5.2 and epithelial membrane antigen but not with S-100 protein. The glandular epithelium was focally positive for carcinoembryonic antigen. The histogenesis of the glandular elements in these tumours is still debated. The variable size of the glandular structures in our case was evidence against an entrapped normal sweat gland origin. The glandular epithelium did not stain with S-100 protein at all, but stained with CAM 5.2, which did not support a direct metaplastic origin of the epithelial elements from the schwannian component. A few scattered CAM 5.2-positive cells and microglandular structures in our case may be the initial differentiating epithelial elements possibly derived from pluripotential neural crest cells.

Glandular malignant peripheral nerve sheath tumor: an unusual case showing histologically malignant glands

In this report, we describe a highly unusual case of glandular malignant peripheral nerve sheath tumor presenting as a neck mass in a previously healthy 29-year-old man. Grossly, the tumor was found to arise from a swollen peripheral nerve trunk. The tumor was largely composed of spindle cells that demonstrated marked nuclear pleomorphism and numerous abnormal mitotic figures. In addition, histologically malignant glandular structures lined by simple nonciliated columnar cells with goblet cells were found clustered in the center of the tumor. Examination of the swollen peripheral nerve trunk revealed the presence of a plexiform neurofibroma. The spindle cells were positive for S100. The glands were negative for S100 but positive for keratin, epithelial membrane antigen, and neuroendocrine markers (somatostatin, chromogranin, Leu-7, and calcitonin). This patient was subsequently diagnosed as having von Recklinghausen disease and died of tumor metastasis to the lungs 34 months after the presentation. To our knowledge, only 3 similar cases have been previously described in the literature.

Schwannoma with features mimicking neuroblastoma: report of two cases with immunohistochemical and ultrastructural findings

OBJECTIVE

A study of two cases of a rare variant of benign schwannoma showing areas mimicking neuroblastoma/peripheral primitive neuroectodermal tumour (PNET).

METHODS

Sections of formalin fixed, paraffin embedded specimens were studied by tinctorial stains and immunohistochemistry, and the tissue retrieved from formalin was examined by electronmicroscopy in one case.

RESULTS

The tumours were small and subcutaneous. Both showed features of benign schwannoma; one had a multinodular plexiform pattern. In addition, rosette-like structures consisting of collagenous cores surrounded by small round cells or slightly larger epithelioid cells were present. Tumour cells were positive for S100 protein, Leu7, and in one case GFAP, but were negative for neurofilament protein, synaptophysin, and MIC2. Type IV collagen surrounded individual cells. Electronmicroscopy in case 2 confirmed schwannian features (lamina, processes) and failed to show features of neuroblastoma (neuroendocrine granules).

CONCLUSIONS

Benign schwannomas may contain rosette-like structures mimicking neuroblastoma/PNET. The techniques used confirmed schwannian differentiation only and eliminated neuroblastoma/PNET. These uncommon variants should be recognised by practising histopathologists to avoid erroneous diagnoses and inappropriate treatment.

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.

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.

Glandular peripheral nerve sheath tumors

BACKGROUND

Peripheral nerve tumors (PNT) containing glands are uncommon. Which types of PNT contain glands is a matter of controversy, a factor bearing on the prognosis of these tumors.

METHODS

The authors reviewed the files of 11 patients with glandular PNT seen in their laboratory and 27 patients reported in the literature.

RESULTS

The 11 instances of glandular PNT seen in their laboratory affected male and female patients equally; patients ages ranged from 8 to 68 years (mean, 28 years). Six patients had neurofibromatosis-1 (NF-1). Eleven of the tumors were histologically malignant PNT, and one was a benign neurofibroma. There were no schwannomas (neurilemomas). The glands were discrete, usually localized to a few areas and in every patient were lined by a keratin-positive epithelium, which in two patients was malignant. One tumor also contained areas of rhabdomyosarcoma, chondrosarcoma, and osteosarcoma (a pluridirectional malignant PNT). Treatment in all patients was some form of surgical resection, followed by radiation in three and chemotherapy in two. Follow-up data were available for nine patients; six of eight patients died with disease. Review of the literature revealed two purported glandular schwannomas (neurilemomas). The authors think these patients had schwannomas containing trapped skin adnexa. Overall, 74% of the patients had NF-1. Ninety-two percent of the tumors were histologically malignant, and 23% of the malignant tumors were pluridirectional malignant PNT. Of the 21 patients for whom follow-up was available, 71% died with tumor.

CONCLUSION

Most glandular PNT are histologically malignant and often are fatal.

Schwannoma with sweat duct differentiation

We report a schwannoma with well differentiated ducts resembling cutaneous sweat ducts. The tumor presented as a painless mass near the left knee of a 41-year-old female. The mass had been present for many years. Some increase in size had been noticed over the previous 2 to 3 yr. The bulk of the tumor was composed of spindle cells with the appearance of Antoni A and Antoni B tissue. Rare mitotic figures were noted. In several areas of the tumor, numerous well-differentiated ducts were present. Most resembled normal cutaneous sweat ducts. In some areas, cystic dilatation of the ducts was present. Focal areas demonstrated poorly formed ducts and single cells with prominent nuclei and ample cytoplasm. Well formed ducts, poorly formed ducts, and single cells marked with AE 1/3 (keratin) and epithelial membrane antigen. The spindle cell proliferation marked for S 100 protein and vimentin. Sweat duct differentiation has not been reported previously in either benign or malignant schwannoma. Light and electron microscopic features of this tumor are presented.