Peripheral nerve, Psammamatous melanotic schwannoma [LMP77373]

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Image Details
Diagnostic Modality: 
Whole Slide Image
Disease Category: 
Neoplasia
Diagnosis: 
Psammomatous melanotic schwannoma
Species: 
Human
Organ System: 
Peripheral Nerve and Skeletal Muscle
Gender: 
Female
Age: 
20 years
Diagnosis Code: 
ICD-10: D36.1 | ICD-O: 9560/0
Slide Contributor Information
Gao, A., Munoz, D.

Keywords

Peripheral nerve sheath tumour, melanin, Carney complex, psammoma body

Clinical History

20-year-old woman with long standing back pain radiating down the right leg and numbness in the S1 dermatome. Neuroimaging shows a large extradural lesion in the L5-S1 neural foramen, compressing the nerve root.

Clinical Discussion

Psammomatous melanotic schwannoma is a rare tumour of peripheral nerves. It is a variant of melanotic schwannoma, which is itself a variant of schwannoma. The tumour cells have the ultrastructure and immunophenotype of Schwann cells (S100 positive) but also contain melanosomes and are reactive for melanoma markers (e.g. HMB-45, Melan-A). Microscopically, they are pigmented lesions composed of spindled and epithelioid cells; psammoma bodies are numerous. Nuclear atypia is not uncommon and 10% of these tumours follow a malignant course. About 50% of psammomatous melanotic schwannomas are associated with Carney complex, an autosomal dominant condition characterized by lentigines, cardiac myxoma, and endocrine overactivity.