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Bladder
Other tumors
Leiomyosarcoma
Author: Nat Pernick, M.D. (see Authors page)
Revised: 26 December 2009, last major update - December 2009
Copyright: (c) 2002-2009, PathologyOutlines.com, Inc.
Definition
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● Sarcoma of smooth muscle origin, similar to counterparts elsewhere
Terminology
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Epidemiology
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● Usually men
● Mean age 49-64 years
● Increased risk after cyclophosphamide treatment (Mod Path 2003;16:512) or radiotherapy; possibly after hereditary retinoblastoma (J Clin Pathol 2003;56:233)
● Acrolein, a metabolite of cyclophosphamide, is excreted in urine and may cause hemorrhagic cystitis, increasing risk for various bladder cancers
Sites
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● Occurs at any site in bladder
Etiology
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● Rare (0.1% of bladder malignancies), but most common nonepithelial malignancy of bladder
Clinical features
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● Aggressive; > 60% develop metastases or die of disease
● Even low grade tumors may metastasize (AJSP 2002;26:292)
● 5 year survival rate for high grade leiomyosarcoma is 62%
Prognostic factors
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●
Case reports
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● 16 year old boy with myxoid leiomyosarcoma (Archives 1987;111:359)
● 49 year old woman with retinoblastoma at age 2 years (Archives 2001;125:1231)
Treatment
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● Radical cystectomy with wide margins (Int Urol Nephrol 2008;40:311)
● Systemic chemotherapy for metastases or combined with radiation therapy prior to surgery for improved resectability
Clinical images
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●
Gross description (Macroscopy)
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● Mean 7 cm, range 3-15 cm, often in bladder dome, well or poorly circumscribed, invasive with ulcerating surfaces
Gross images
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leiomyosarcoma of prostate extending into bladder neck
Micro description (Histopathology)
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● Cellular, interlacing fascicles of spindled cells with eosinophilic cytoplasm, paranuclear cytoplasmic vacuoles and blunt ended nuclei
● Usually has infiltrative margins and invades muscularis propria (AJSP 1989;13:480)
● Variable nuclear atypia
● Coagulative tumor necrosis common
● Mean 12 mitosis/10 HPF
● May be myxoid and resemble inflammatory pseudotumor
High grade:
● Moderate/marked cytologic atypia, 5+ mitotic figures/10 HPF or abundant necrosis
Myxoid subtype:
● May resemble inflammatory myofibroblastic tumor, but has destruction of muscle fascicles at tumor-muscle interface
● Also nuclear pleomorphism and tumor necrosis (not present in inflammatory myofibroblastic tumor)
Micro images
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Interlacing fascicles of spindled cells with atypia and mitotic figures #1; #2
Malignant spindle cell tumor with mitotic activity
Spindle cell tumor with pleomorphism and high mitotic rate
Nuclear pleomorphism is evident #1; #2; #3
Epithelioid subtype:
Cells have abundant eosinophilic cytoplasm, vesicular nuclei and prominent nucleoli; actin+
Myxoid subtype:
Resembles inflammatory pseudotumor at low power; At high power, there is significant nuclear atypia and necrosis
Cytology description
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●
Cytology images
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Positive stains
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● Smooth muscle actin (80%), h-caldesmon (Hum Pathol 1999;30:392), muscle specific actin (HHF35)
● Desmin (40%), calponin, vimentin
● Often positive for cytokeratin Oscar or AE1-AE3 (Am J Surg Pathol 2009;33:99)
Negative stains
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● EMA, S100, ALK-1 (Mod Pathol 2007;20:592)
● 34betaE12, CK 5/6
Electron microscopy descriptions
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●
Electron microscopy images
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Molecular / cytogenetics description
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● Usually not diploid
Molecular / cytogenetics images
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Differential Diagnosis
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● Inflammatory myofibroblastic tumor: vascular and inflamed myofibroblastic proliferation without cytologic atypia, not as cellular as leiomyosarcoma, no necrosis, no abnormal mitotic figures, ALK1+, H-caldesmon negative (Diagn Pathol 2008 Mar 13;3:11)
● Postoperative spindle cell nodule: history of recent surgery/trauma, no atypia
● Sarcomatoid carcinoma: strongly keratin positive, epithelioid differentiation
Additional references
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●
End of Bladder > Other tumors > Leiomyosarcoma
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