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Bladder

Other tumors

Leiomyosarcoma


Reviewers: Gillian Levy, M.D., Yale Medical Center (see Reviewers page)
Revised: 23 September 2012, last major update April 2011
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

Definition
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● Sarcoma of smooth muscle origin, similar to counterparts elsewhere

Epidemiology
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● Usually men
● Mean age 49-64 years
● Increased risk after cyclophosphamide treatment (Mod Pathol 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, and can rarely involve the ureter or renal pelvis

Etiology
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● Rare (0.1% of bladder malignancies), but most common nonepithelial malignancy of bladder
● Arises from urinary bladder smooth muscle

Clinical features
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● Aggressive; > 60% develop metastases or die of disease
● Even low grade tumors may metastasize (Am J Surg Pathol 2002;26:292)
● 5 year survival rate for high grade leiomyosarcoma is 62%

Prognostic factors
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● Generally poor prognosis with local recurrence or metastatic disease

Case reports
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● 16 year old boy with myxoid leiomyosarcoma (Arch Pathol Lab Med 1987;111:359)
● 49 year old woman with retinoblastoma at age 2 years (Arch Pathol Lab Med 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

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
● Necrosis is frequently found in high grade lesions

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 (Am J Surg Pathol 1989;13:480)
● Variable nuclear atypia
● Coagulative tumor necrosis common
● 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


H&E and smooth muscle actin


Malignant spindle cell tumor with mitotic activity


Spindle cell tumor with pleomorphism and high mitotic rate

       
Nuclear pleomorphism is evident


p53+


Epithelioid subtype


Myxoid subtype resembles inflammatory pseudotumor at low power; at high power, there is significant nuclear atypia and necrosis

Cytology description
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● Spindle cells with mild to moderate nuclear hyperchromasia

Positive stains
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● Smooth muscle actin (80%), h-caldesmon (Hum Pathol 1999;30:392), muscle specific actin (HHF35), desmin (< 50%), 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, CK5/6

Molecular/cytogenetics description
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● Usually not diploid

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

End of Bladder > Other tumors > Leiomyosarcoma


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