Home   Chapter Home   Jobs   Conferences   Fellowships   Books



Advertisement

Soft tissue tumors

Skeletal muscle

Pleomorphic rhabdomyosarcoma


Reviewer: Vijay Shankar, M.D. (see Reviewers page)
Revised: 22 February 2013, last major update November 2012
Copyright: (c) 2003-2013, PathologyOutlines.com, Inc.

Definition
=========================================================================

● High grade sarcoma of adults with bizarre polygonal, round or spindle cells, with skeletal muscle differentiation and no alveolar or embryonal component
● Rarely has smooth muscle or fibrohistiocytic differentiation (Ultrastruct Pathol 2010;34:42)

Epidemiology
=========================================================================

● Rare, but common rhabdomyosarcoma subtype in adults
● Usually age 50+; can occur in children (Ann Diagn Pathol 2001;5:199), but then called anaplastic
● 70% male

Clinical features
=========================================================================

● Rapidly growing painful mass, most commonly of lower extremity, abdomen / retroperitoneum, chest / abdominal wall or spermatic cord / testes, uterine corpus, upper extremity, orbit
● Similar behavior to other pleomorphic sarcomas

Case reports
=========================================================================

● 18 year old man with painless scrotal mass (Diagn Cytopathol 2010;38:121)
● 34 year old man with scrotal tumor (Nihon Hinyokika Gakkai Zasshi 2009;100:545)
● 59 year old man with painful inguinal swelling and deep vein thrombosis (Case Rep Oncol 2012;5:74)
● 71 year old woman with retroperitoneal tumor with osteoclast-like giant cells (Arch Pathol Lab Med 2005;129:703)

Treatment and prognosis
=========================================================================

● Poor prognosis
● 70% die of disease after mean follow-up of 20 months (Mod Pathol 2001;14:595)

Diagnosis
=========================================================================

● Must prove skeletal muscle differentiation by cross striations or skeletal muscle marker immunoreactivity
● No alveolar or embryonal component
● Common errors involve entrapped skeletal muscle, non-specific myoglobin immunoreactivity or skeletal muscle differentiation of other tumors

Gross description
=========================================================================

● Mean 7 cm, up to 30 cm
● May be confined to fascial compartment and assume shape of muscle from which it arises
● White, firm cut surface with variable hemorrhage and necrosis

Gross images
=========================================================================



Various images

Gross images
=========================================================================



Hand

Micro description
=========================================================================

● Well circumscribed
● Large, multinucleated, bizarre, eosinophilic tumor cells
● Should see cross striations or have immunohistochemical evidence of skeletal muscle differentiation
● No alveolar or embryonal component (by definition)
Classic type: predominantly atypical rhabdomyoblasts in sheets
Round cell type: clusters of rhabdomyoblasts in background of slightly atypical, medium sized, round blue rhabdomyoblasts
Spindle cell type: scattered rhabdomyoblasts with predominantly atypical spindled rhabdomyoblasts in storiform pattern

Micro images
=========================================================================

Classic, round cell and spindle cell variants

Fascicular pattern

Storiform pattern

Patternless pattern

Hemangiopericytoma-like pattern

Spindle cells

Pleomorphic and polygonal cells

Epithelioid cells with abundant eosinophilic cytoplasm

Clear cytoplasm due to washing out of glycogen

Psoas muscle tumor cells have abundant eosinophilic cytoplasm with hyaline like inclusions, osteoclast-like giant cells

Various images

Positive stains
=========================================================================

● Myoglobin (>90%), desmin (>90%), muscle specific actin (70%)
● MyoD1 (50%), skeletal muscle myogenin (50%), smooth muscle actin (50%)
● Rarely CD 10 and CD 56

Negative stains
=========================================================================

● Cytokeratin 7, synaptophysin, epithelial membrane antigen, placental-like alkaline phosphatase, chromogranin, and a pan-keratin

Electron microscopy description
=========================================================================

● Skeletal muscle differentiation with rudimentary sarcomeres containing Z bands or Z band material with thick and thin filaments

Electron microscopy images
=========================================================================



Thick and thin filaments from primitive Z bands

Molecular / cytogenetics description
=========================================================================

● Complex karyotype (Cancer Genet Cytogenet 2009;192:1)
● Comparative genomic in situ hybridization (CGH) reveals eight highly amplified regions at 1p36.1-p36.2, 1p31-p32, 1q21-q31, 8q12-q21, 8q24-qter, 11q12-q13, 12q13-q14 and 18q12-q22 (Am J Cancer Res 2012;2:141)

Differential diagnosis
=========================================================================

Embryonal or alveolar rhabdomyosarcoma with pleomorphism
MFH-pleomorphic: diagnosis of exclusion, no evidence of skeletal muscle differentiation
Pleomorphic liposarcoma
● Sarcoma with heterologous rhabdomyosarcomatous differentiation: differentiated features are characteristic of primary tumor

End of Soft tissue tumors > Skeletal muscle > Pleomorphic rhabdomyosarcoma


This information is intended for physicians and related personnel, who understand that medical information is often imperfect, and must be interpreted in the context of a patient's clinical data using reasonable medical judgment. This website should not be used as a substitute for the advice of a licensed physician.

All information on this website is protected by copyright of PathologyOutlines.com, Inc. Information from third parties may also be protected by copyright. Please contact us at copyrightPathOut@gmail.com with any questions (click here for other contact information).