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Soft Tissue Tumors Part 3
Muscle, Vascular, Nerve, Other
Epithelioid leiomyosarcoma
Author: Nat Pernick, M.D, PathologyOutlines.com, Inc.
Revised: 11 August 2009, last major update - August 2009
Copyright: (c) 2002-2009, PathologyOutlines.com, Inc.
Leiomyosarcoma: general, cutaneous, epithelioid, myxoid, pleomorphic, rhabdoid features
Epidemiology
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● Rare
Sites
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● Usually in uterus; rarely in bone, soft tissue, skin or subcutis (Am J Surg Pathol 1994;18:232)
● In stomach is also called leiomyoblastoma
Case reports
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● Infant with intraabdominal mass (Mod Path 2000;13:1156)
● 56 year old man with tumor of gastrocolic ligament (Acta Chir Belg 2003;103:105)
● 71 year old man with rectal tumor with osteoclast-like giant cells (Arch Pathol Lab Med 2000;124:438)
● 78 year old man with thigh tumor (Archives 2002;126:468)
MRI images
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18 month old girl with intraabdominal mass
Micro description
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● Round/polygonal cells with eosinophilic and vacuolated cytoplasm, vesicular nuclei
● Arranged in sheets with focal spindle cells
Micro images
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Various images PAS stain
Bladder tumor: H&E and actin
Cytology
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● Mononuclear, binucleated or multinucleated cells with eccentric nuclei and dense to vacuolar cytoplasm (Acta Cytol 1997;41:1801)
● Also highly cellular smears with many single polygonal cells having eccentric, malignant nuclei and a characteristic clear quality to the cytoplasm in Pap-stained material (Diagn Cytopathol 1994;11:321)
Positive stains
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● Alpha-smooth muscle actin, alpha-sarcomeric actin, vimentin
● Also CD99/MIC2
● Reticulin stain outlines individual tumor cells
Negative stains
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● CAM 5.2, EMA, CD34, CD45; usually desmin
● Factor VIII, Glial fibrillary acidic protein, HMB45, S100, CD1a (Ann Diagn Pathol 2008;12:401)
Electron microscopy
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● Abundant actin-type filaments in cytoplasm of some cells, glycogen
Electron microscopy images
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Intermediate filaments, thin filaments with
subplasmalemmal dense bodies and glycogen
Differential Diagnoses
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● Metastatic uterine tumor - clinical history
● Metastatic carcinoma - clinical history, keratin+, no areas of classic leiomyosarcoma
● Epithelioid sarcoma
● Melanoma - S100+, HMB45+
End of Soft Tissue Tumors Part 3 - Muscle, Vascular, Nerve, Other > Epithelioid leiomyosarcoma
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