Bladder - Neurofibroma

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Bladder

Benign tumors

Neurofibroma

Reviewer: Monika Roychowdhury, M.D., University of Minnesota Medical Center (see Reviewers page)
Revised: 3 July 2011, last major update May 2011
Copyright: (c) 2003-2011, PathologyOutlines.com, Inc.

Definition
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● Benign mesenchymal tumor with nerve sheath differentiation
● Similar to counterparts elsewhere

Epidemiology
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● Uncommon
● Classically occurs in young patients with a slight male predominance
● Presents early in life
● Strongly associated with neurofibromatosis type 1 (Cancer 1999;86:505, PDF)

Clinical features
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● Plexiform neurofibromas are associated with neurofibromatosis; diffuse neurofibromas are not (Am J Surg Pathol 2008;32:907)
● May present with hematuria, irritative voiding symptoms and symptoms related to pelvic mass effect

Case reports
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● 6 year old girl with neurofibromatosis-1, bladder plexiform neurofibroma and diffuse ganglioneuromatosis of bladder (Hum Pathol 2008;39:1708)
● 14 year old girl with pelvic plexiform neurofibroma involving urinary bladder (Pediatr Radiol 2008;38:916)
● 18 year old man with neurofibromatosis-1 (Radiographics 2004;24 Suppl 1:S237)

Gross description
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● Polypoid or diffuse

Gross images
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Plexiform neurofibroma: M - mucosa is surrounded by masses of nodules

Micro description
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● Histology is same as neurofibromas elsewhere
● Hypocellular proliferation of spindle cells with wavy bland nuclei
● Cells are arranged in loose fascicles intermixed with bundles of collagen

Micro images
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Lamina propria shows meissner-type corpuscles

Bland spindled cells in fibrous stroma

Plexiform neurofibroma

Other images: Replacement of bladder wall #1, #2

Positive stains
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● S100

Negative stains
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● Keratin, smooth muscle actin, desmin, calponin, caldesmon, EMA, p53

Differential diagnosis
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● Leiomyoma: has cigar-shaped nuclei, S100 negative, positive for smooth muscle actin and desmin
● Inflammatory myofibroblastic tumor: reactive spindle cells in inflammatory background
● Malignant peripheral nerve sheath tumor: has marked atypia and increased mitotic activity, may have necrosis

End of Bladder > Benign tumors > Neurofibroma

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