Pseudoglandular schwannoma

Glandular Schwannoma With Apocrine Decapitation Secretion: A True Divergent Differentiation or Entrapped Normal Tissue?

ABSTRACT

We report an unusual case of schwannoma with glandular elements that demonstrated apocrine decapitation secretion. The glandular structures were embedded within the tumor, varied in shape and size, and were lined by a double-to-multilayered epithelium, with the inner layer composed of monomorphous cuboidal to columnar cells, focally with apocrine decapitation secretion, and the outer layer representing myoepithelial cells. A normal eccrine unit was observed near the lesion. Immunohistochemical studies showed that all luminal cells of the glandular structures stained positive for CK7, whereas myoepithelial cells expressed S100 and p63, and epithelial membrane antigen highlighted the luminal border. CK20 and neuroendocrine markers were negative in the glandular elements.Our findings suggest that the origin of the glandular elements in our case was represented by entrapped glands. Two theories may explain the epithelial hyperplasia observed in the present case as follows: the obstructive effect theory and the inductive ability of a mesenchymal proliferation to produce epidermal or adnexal changes. We suggest that, in a subset of cases, the origin of the glandular elements might represent entrapped glands, wherein their histomorphology/cytomorphology recapitulates the elements comprising the normal adjacent tissue. Further research is necessary to elucidate the histogenesis of glandular 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.

Primary adrenal schwannoma: a series of 31 cases emphasizing their clinicopathologic features and favorable prognosis

PURPOSE

Primary adrenal schwannoma (PAS) is a very rare benign tumor, and most of them have been described in case reports. This study aimed to analyze their distinct clinicopathologic features and follow-up data through the largest series yet.

METHODS

Clinicopathologic features of 31 primary adrenal schwannomas were retrospectively studied. Imaging and histologic features were re-evaluated and summarized. Immunohistochemical markers were measured, including S100, SOX10, AE1/AE3, EMA, SMA, Desmin, HMB45, GLUT1, and Ki67. Follow-up of all cases was performed.

RESULTS

All the tumors were clinically misdiagnosed as nonfunctioning adrenal adenoma (NAA; 23/31), aldosterone-producing adenoma/aldosteronoma (APA; 3/31), cortisol-producing adenoma (CPA; 3/31), or pheochromocytoma (PCC; 2/31). Some 87% (27/31) presented with adrenal incidentaloma, and 13% (4/31) had a clinical symptom or unregulated hormone levels. They comprised conventional (19/31), cellular (7/31), plexiform (2/31), ancient (1/31), epithelioid (1/31) and microcystic/reticular variants (1/31) and had various histologic features. Immunohistochemically, all tumors (31/31) were positive for S100 and Sox10, with a low Ki-67 proliferative index. In the long-term follow-up (mean, 53 mo.; median, 56 mo.), none had evidence of recurrence and metastasis. Univariate analysis showed that OS and DFS were not associated with age; sex; tumor side, size, or number; adrenal-related symptoms; gross feature (solid vs. cystic); or any histologic feature (P > 0.9999).

CONCLUSION

PAS is an extremely rare tumor and mostly appears as an incidentaloma. Clinically, it tends to be misdiagnosed as other common adrenal tumors. This tumor has a benign biologic behavior and prognosis, without correlations with clinical or histologic parameters.

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.

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.

Schwannoma: a rare benign tumor of soft tissues

'Schwannomas are unusual benign tumors which arise from the surface of neural elements of the body or within the brain. They do not as a rule metastasize but may cause sometimes severe local problems on the nerves, blood vessels and adjacent bone. The tumors arise from the Sheath of Schwann, a structure on the surface of a nerve. The lesions may expand and cause considerable damage to adjacent tissues. They do not arise within bone since there are no Sheaths of Schwann within the osseous tissue but may cause local damage to the bony cortex and sometimes fractures. Rarely the lesions may metastasize and cause patients' death. The treatment is usually local resection, and most often is successful although may cause damage to the adjacent nerve.

Multinodular reticular schwannoma in the head and neck region: a potential diagnostic pitfall

Reticular/microcystic schwannoma is a recently described morphologic variant of schwannoma that occurs predominantly in visceral organs, most commonly the gastrointestinal tract. This report describes a case occurring in the masticator space, accompanied by focal erosion of the orbital floor, clinically and radiologically worrisome for malignancy. The 26-year-old man presented with facial swelling for 3 month. The tumor shows a multinodular appearance, with dense lymphoplasmacytic infiltrates in the fibrous septa. The tumor nodules are composed of plump spindle cells disposed in a reticular pattern. The diagnosis is confirmed by strong positive staining for S100 protein. The differential diagnoses of reticular schwannoma in the soft tissues of head and neck region are different from those in the gastrointestinal tract.

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 multicystic peritoneal mesothelioma: cases reports in the family with diverticulosis and literature review

We report on benign multicystic peritoneal mesothelioma in two siblings whose family had a history of multiple familial diseases including diverticulosis. After a genetic evaluation and a chromosomal analysis, we were not able to identify a specific genetic cause of the family's pattern of disease. We assumed that previous surgical procedures and the chronic inflammatory process from diverticulitis were the underlying etiology. Both patients had multiple recurrences with indolent courses similar to those reported in other cases. After the recurrences, one patient was treated with cystic aspiration and the other with hormones. The cysts in both cases regressed partially but the patients were relieved of their clinical symptoms, for 2 years after cystic drainage in one case and for 5 years after hormonal treatment in the other.

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.

Schwannoma with rhabdomyoblastic differentiation: a unique variant of malignant triton tumor

A 54-year-old woman presented with intractable perianal, bilateral buttock, and radiating thigh/calf pain. An MRI scan showed an intradural, contrast-enhancing, ovoid mass in the cauda equina region at L1-L2. At laminectomy, the ovoid mass arose from a nerve root and, intact, was gross totally resected. Histologically, the dominant pattern was that of schwannoma. One year thereafter, the symptoms recurred. An MRI scan demonstrated an irregular, heterogeneously enhancing tumor recurrence. A repeat laminectomy disclosed a large fleshy tumor involving multiple nerve roots. The lesion was subtotally resected and showed pluridirectional differentiation toward embryonal rhabdomyosarcoma, primitive neuroectodermal tumor, and rare malignant epithelial cells. Review of the original tumor disclosed only foci of embryonal rhabdomyosarcoma and primitive neuroectodermal tumor. Based upon available data regarding divergent differentiation in peripheral nerve sheath tumors, this is a unique, previously undescribed tumor demonstrating rhabdomyosarcomatous, primitive neuroectodermal tumor and scant epithelial differentiation in a schwannoma. In essence, it is a variant of malignant Triton tumor because of its origin in a tumor consisting of well-differentiated Schwann cells. It supports the contention that the Schwann cell is the source of a variety of heterologous elements in nerve sheath tumors.

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.

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.