Custom Search


Pathology of Schwannoma

Dr Sampurna Roy MD

Dermatopathology Quiz Case 146

Diagnosis: Plexiform Schwannoma

Path Quiz Case 6: Case history and images

Diagnosis: Ancient Schwannoma


  February 2016

Dr Sampurna Roy  MD

Consultant  Histopathologist (Kolkata - India)




Myxoid Tumours of Soft Tissue

Classification of Soft  Tissue Tumour

Gross examination of soft tissue specimen          

A practical approach to histopathological reporting of soft tissue tumours

Grading of soft tissue tumours

Lipomatous tumours

Neural tumours

Myogenic tumours

Fibroblastic/ Myofibroblastic tumours

Myofibroblastic tumours

Fibrohistiocytic tumours

ChondroOsseous tumours

Soft TissueTumours of Uncertain Differentiation               

Notochordal Tumour - Chordoma

Extra-adrenal Paraganglioma

Gastrointestinal Stromal Tumour


Vascular tumours


Epithelioid hemangioma 

Lobular capillary hemangioma (pyogenic granuloma

Bacillary angiomatosis

Verruga Peruana

Acro-angiodermatitis / pseudo-Kaposi's sarcoma

Reactive angioendotheliomatosis

Infantile Hemangioma

Glomeruloid hemangioma 

Acquired tufted  angioma

Cherry angioma/senile angioma

Arteriovenous hemangioma 


Spindle cell  hemangioma / hemangioendothelioma

Kaposiform hemangioendothelioma 

Retiform hemangio endothelioma 

Papillary intralymphatic angioendothelioma (Dabska's tumour)

Composite hemangio endothelioma 

Polymorphous  hemangioendothelioma

Kaposi's sarcoma

Epithelioid hemangio endothelioma



Granulomatous Reaction Pattern of the Skin

Granuloma Annulare

Necrobiosis Lipoidica

Necrobiotic Xanthogranuloma   

Rheumatoid Nodule

Lupus Vulgaris

Cutaneous Sarcoidosis

Melkersson Rosenthal Syndrome

Annular Elastolytic Giant Cell Granuloma

Skin lesion in Crohn's Disease

Blastomycosis-like pyoderma

Foreign body granuloma


Interstitial Granulomatous Dermatitis

Interstitial Granulomatous Drug Reaction

Erythema Nodosum





Toxic Shock Syndrome

Allergic Granulomatosis (Churg-Strauss Syndrome)

Median Raphe Cyst

Cutaneous Ciliated Cyst

Infective Panniculitis

Pancreatic Panniculitis

Drug related cutaneous lesions

Cutaneous lesion in graft-
versus host disease


Reactive and hamartomatous lesions:

Traumatic neuroma

Morton's neuroma

Digital Pacinian neuroma

Nerve Sheath Ganglion

Fibrolipomatous hamartoma of nerve

Benign tumours:

Solitary circumscribed neuroma

Neurofibroma and  variants 


Dermal nerve sheath myxoma

Cellular neurothekeoma

Granular cell tumour

Malignant tumour:

Malignant peripheral nerve sheath tumour

Neuroendocrine  Carcinoma:

Merkel cell  carcinoma

Malignant primitive neuroectodermal tumour

Miscellaneous neuroectodermal tumours presenting in soft tissue:

Subcutaneous Myxopapillary Ependymoma  

Heterotopic Glial Nodule

Heterotopic Meningeal Lesions

Syn: Neurilemmoma

Schwannoma (Neurilemmoma) are slow growing benign nerve sheath tumours.

These are usually solitary lesions.

Multiple lesions are rare and may occur in the following clinical settings: 

i)  multiple localized tumours.

ii)  In association with neurofibroma in von Recklinghausen's disease.

iii) In schwannomatosis,  a non hereditary disease characterized by multiple subcutaneous  and intradermal schwannomas together with tumours of internal organs.

Age: Common in patients  between the ages of 20 and 50. 

Site: These are usually located on the head and neck and flexor surface of upper and lower extremities. The spinal roots, cervical, sympathetic, vagus and ulnar nerves are commonly involved.

The deeply located  lesions are situated in the retroperitoneum and the posterior mediastinum.


The tumour is surrounded by true capsule consisting of the epineurium.

Tumour arising in a small nerve resemble a neurofibroma and often obliterate the nerve of origin.

Tumours arising in larger nerves present as  eccentric masses.

Cut surface reveals smooth, glistening, grey-white appearance.

There may be cystic areas with areas of hemorrhage and calcification.

Microscopic features:

Schwannomas are usually solitary, well circumscribed, encapsulated lesions, mostly confined to the subcutis.

Multinodular lesions may be present in the dermis, this is known as 'plexiform neurilemmoma'.

The characteristic features include presence of alternating Antoni A and Antoni B areas Antoni A area is composed  of spindle shaped Schwann cells arranged in interlacing fascicles.

There may be nuclear palisading.

In between two compact rows of well aligned nuclei , the  cell processes form eosinophilic Verocay bodies.

Mitotic figures may be present (usually less than 5 per 10 high power field).
Antoni B area consists of loose meshwork of gelatinous and microcystic tissue. 

Large, irregularly spaced, thick walled blood vessels  are noted in Antoni B area.

These may contain thrombus material in the lumina.

Immunohistochemistry: S100 protein is strongly expressed by most cells of schwannoma.


The cells also express Vimentin and myelin basic protein.

Differential diagnosis: Neurofibroma ; Palisaded encapsulated neuroma (more number of axons and Schwann cells in interlacing fascicles together with cleft like spaces

Cutaneous leiomyoma  (smooth muscle actin and desmin positive) ;   

Palisaded myofibroblastoma ( involve lymph nodes, contain fibroblastic and myofibroblastic cells and are S100 protein negative).   


Ancient Schwannoma: 


This is a variant of Schwannoma displaying prominent degenerative changes.

The degenerative changes include cyst formation, calcification, hemorrhage and  hyalinization.

Macroscopically, these are large tumours which are usually deeply located (Example: retroperitoneum).

There is prominent cellular atypia  characterized by hyperchromatic nuclei and coarse clumping of chromatin.

These changes are purely degenerative.

No mitotic figures are identified.

These tumours behave as ordinary schwannomas.

Further reading:

Degenerative (ancient) changes in benign cutaneous schwannoma. A light  microscopic, histochemical and immunohistochemical study.

Fine needle aspiration cytology of ' ancient ' schwannoma.

Degenerative changes in parapharyngeal schwannoma ancient schwannoma. Case report and review of literature.

Malignant peripheral nerve sheath tumour arising in benign ancient schwannoma : a case reprt with an immunohistochemical study.

Cellular Schwannoma

This variant is usually found in the deeper tissues (retroperitoneum or mediastinum).

Histologically, there are compact spindle shaped cells arranged in a fascicular or whorled growth pattern.


Verocay bodies and Antoni B areas are not conspicuous.

Mitotic figures are present (more that 10 per10 high power fields).

The thick fibrous capsule around the tumour shows a dense lymphocytic infiltrate.

Differential diagnosis include low grade malignant peripheral nerve seath tumour and leiomyosarcoma.

Immunohistochemistry reveals strong and diffuse positivity with S100 protein.

Desmin is negative.

Visit: Intranodal Palisaded Myofibroblastoma

Further reading:

Cellular schwannoma. A clinicopathologic, DNA flow cytometric, and proliferation marker study of 70 patients.

Cellular schwannoma: a distinct pseudosarcomatous entity.

Melanotic Schwannoma

This rare variant usually occurs in middle aged adults and  commonly arises from  the posterior spinal nerve roots.

Melanotic schwannomas are well circumscribed, partly encapsulated lesions characterized by polygonal and vesicular cells with grooved nuclei. These cells contain abundant melanin pigment.

In psammomatous melanotic schwannoma, varying numbers of psammoma bodies are present.

Some of these cases are associated with Carney's complex (myxoma, spotty pigmentation and endocrinopathy).

Malignant melanotic schwannoma usually  arises from the sympathetic chain and is characterized by brisk mitosis and prominent nucleoli.

Immunohistochemistry reveals that tumour cells stain positively for S100 protein , HMB45,  MART-1, synaptophysin and vimentin.


Further reading:

Cutaneous psammomatous melanotic schwannoma: non-recurrence with surgical excision.

Multiple melanotic schwannoma.

Melanotic schwannoma, a tumor with a unpredictable prognosis: case report and review of the literature.

Neuroblastoma - like Schwannoma


Benign schwannomas may contain rosette-like structures mimicking neuroblastoma/PNET.

Tumour cells are positive for S100 protein and negative for neuronal markers synaptophysins and neurofilament protein.

MIC2 is negative (rules out PNET type differentiation).

Individual cells were surrounded by type IV collagen.

This is a feature characteristically seen in schwannian but not in neuronal tumours.

Further reading:

Neuroblastoma-like neurilemoma. 

Schwannoma with Neuroblastoma-Like Rosettes: An Unusual Morphologic Variant. 

Neuroblastoma-like schwannoma: a case report and review of the literature.

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

Plexiform Schwannoma 


Plexiform schwannoma may demonstrate conventional, cellular, or mixed appearance.


1) Common superficial (dermal and subcutaneous) tumours.

2) Deep somatic soft tissue.

Worrying histologic features are increased cellularity and mitoses.

Differential diagnosis: Plexiform neurofibromas and malignant peripheral nerve sheath tumour.

Further reading:

Deep-seated plexiform schwannoma: a pathologic study of 16 cases and comparative analysis with the superficial variety.

Congenital and childhood plexiform (multinodular) cellular schwannoma: a troublesome mimic of malignant peripheral nerve sheath tumor.

Plexiform schwannoma of the small intestine: report of a case.

The pathobiologic spectrum of Schwannomas.

Perineurial cells and nerve axons in gastrointestinal schwannomas: a similarity with neurofibromas. An immunohistochemical study of eight cases.


Epithelioid Schwannoma:

It was first reported as cutaneous epithelial schwannoma by Kindblom et al in 1998.

These tumors may cause diagnostic errors due to their increased cellularity and epithelioid morphology.

Typical histologic features of classic schwannoma such as Antoni A and B areas, Verocay bodies, and hyalinized vessels are either absent or only present in focal areas.

Strong and diffuse S-100 protein expression is seen in both benign and malignant counterparts of epithelioid schwannoma.

The findings that are suggestive of the benign nature of the lesion are long-term clinical history, small size, superficial localization, encapsulation, bland morphology, lack of mitosis and necrosis, and a benign clinical course after complete excision.

Pathologists should be aware of the epithelioid variant of schwannoma to avoid false diagnosis of malignancy.

Epithelioid schwannoma of the facial nerve masquerading as pleomorphic adenoma: a case report.

Epithelioid schwannoma of soft tissue: unusual morphological variant causing a diagnostic dilemma.

Benign cutaneous epithelioid Schwannoma: case report and review of the literature.

Benign Epithelioid Peripheral Nerve Sheath Tumors of the Soft Tissues: Clinicopathologic Spectrum of 33 Cases.

Expanding the Spectrum of Malignant Change in Schwannomas Epithelioid Malignant Change, Epithelioid Malignant Peripheral Nerve Sheath Tumor, and Epithelioid Angiosarcoma: A Study of 17 Cases

Cutaneous epithelioid schwannomas: a rare variant of a benign peripheral nerve sheath tumor.

Glandular Schwannoma

Benign glandular schwannoma and Recklinghausen disease. Report of a case.

Benign glandular schwannoma.

Benign glandular schwannoma.

Benign glandular schwannoma.

Schwannoma - Perineurioma

Hybrid peripheral nerve sheath tumors: Schwannoma-perineurioma and neurofibroma-perineurioma. A report of three cases in extradigital locations.  

A benign neoplasm with histopathological features of both schwannoma and retiform perineurioma (benign schwannoma-perineurioma): a report of six cases of a distinctive soft tissue tumor with a predilection for the fingers.Virchows Arch. 2004 Oct;445(4):347-53. Epub 2004 Aug 20

Nerve sheath tumours with hybrid features of neurofibroma and schwannoma: a conceptual challenge.






Gallbladder Pathology Online


Pathology Quiz Online 


Paediatric Pathology Online


Pancreatic Pathology Online




Endocrine Pathology Online


Eye Pathology Online


Ear Pathology Online


Cardiac Path Online


Pulmonary Pathology Online


Lung Tumour Online




Nutritional Pathology Online


Environmental Pathology Online


Soft Tissue Tumour Online


GI Path Online-India


Case Index


E-book - History of Medicine  


Microscope - Seeing the Unseen





Privacy Policy  

Advertising Policy

Copyright 2016