Bladder - Post-operative spindle cell nodule

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Bladder

Benign tumors

Post-operative spindle cell nodule

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

Definition
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● Reactive lesion that occurs weeks to months after transurethral resection of prostate (in men) or bladder lesions in area of surgery
● Similar features as inflammatory myofibroblastic tumor, but with a history of surgery
● First described in 1990 (Urology 1990;35:342, J Urol 1990;143:824)

Terminology
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● Also called pseudosarcomatous myofibroblastic proliferation (Am J Surg Pathol 2006;30:787)

Epidemiology
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● Usually women

Clinical features
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● Sometimes incidental
● May present with hematuria or obstructive voiding symptoms

Prognostic factors
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● Excellent prognosis

Treatment
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● Transurethral resection; no recurrences or metastases (Hum Pathol 2007;38:753)

Gross
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● Friable nodule, mean size 1 cm

Micro
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● Cellular, fascicular growth pattern of plump or elongated spindle cells which infiltrate the bladder wall and may focally destroy muscle
● Delicate network of small blood vessels in edematous or myxoid stroma with red blood cell extravasation
● Ulcerated surface with acute and chronic inflammatory infiltrate
● May show low to high mitotic activity but no atypical mitotic figures, resembles sarcoma but no atypia
● No necrosis, no significant pleomorphism

Micro images
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Myofibroblastic cells and inflammatory cells in myxoid stroma

Left: muscularis propria, Right: spindle cell nodule

Fascicular growth

Highly cellular with numerous mitoses

AFIP Fig 2-70: interlacing fascicles of myofibroblasts

Uniform cells are mixed with inflammatory cells

Keratin+

Actin+

Cytology
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● May have intracytoplasmic inclusion bodies (Diagn Cytopathol 1992;8:171)

Positive stains
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● Low molecular weight keratin (CAM 5.2, AE1/AE3), vimentin, actin, desmin, ALK1

Negative stains
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● EMA

Molecular
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● May have trisomy 7 (Cancer Genet Cytogenet 2007;174:147)

Differential diagnosis
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● Kaposi’s sarcoma: no history of recent procedure, primarily a vascular tumor
● Myxoid leiomyosarcoma: no history of recent procedure; has smooth muscle morphology, pleomorphism, atypical mitotic figures, necrosis

Additional references
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● eMedicine

End of Bladder > Benign tumors > Post-operative spindle cell nodule

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