Pediatric Soft-Tissue Sarcomas Beth McCarville, MD St. Jude Children s Research Hospital Memphis, Tn
Overview Histologic classifications Characteristic imaging features Helpful clinical characteristics
Pediatric Soft Tissue Sarcomas Rhabdomyosarcoma 45% Nonrhabdomyosarcoma 55% Malignant peripheral nerve sheath tumor Synovial sarcoma Fibrosarcoma Epithelioid sarcoma
Rhabdomyosarcoma (RMS) Aggressive soft-tissue tumor Arises from undifferentiated mesenchyme Occurs in all tissue except bone Most common ST sarcoma in children Two main histologic types Embryonal Botryoid Spindle cell Alveolar Pleomorphic
Clinical Features of RMS Embryonal accounts for 65% of RMS Botryoid arises from submucosa hollow structures Good prognosis Alveolar Older children Aggressive Poor prognosis Arises in extremities and trunk Propensity for local-regional nodal spread Also metastasizes to lungs, bone, bone marrow, softtissues
seer.cancer.gov/publications/aya/7_sts.pdf - 2008-08-29
Head and Neck Sites Orbit (favorable) Non-parameningeal (favorable) oral cavity larynx/hypopharynx oropharynx scalp parotid cheek neck Parameningeal (unfavorable) middle ear nasal cavity/paranasal sinuses nasopharynx infratemporal fossa/pterygopalatine/parapharyngeal area Courtesy Dr. Sheri Spunt, St. Jude Children s Research Hospital
Embryonal Orbital RMS Favorable Site T1W C- STIR T1W C+
Embryonal Parameningeal RMS Unfavorable Site T1W C+ T1W C+
Genitourinary RMS Second most common site after head and neck Two groups Bladder/prostate: unfavorable site Non-bladder/prostate: favorable site Vast majority are embryonal histology
T2W Bladder RMS Unfavorable Site T1W Patients < 4 years age Arise from or near trigone Botryoid histology Present with Bladder outlet obstruction Hematuria Extruded mucosanguineous material
T1W Prostate RMS Unfavorable Site T1W Occur in infants or older boys Usually very large Present with Bladder outlet obstuction Hematuria Constipation Foley Foley
Genital Tract RMS in Girls Favorable Site Vaginal tumors very young girls Cervical/uterine tumors older girls T1W C- T1W C+
Paratesticular RMS Favorable Site STIR Longitudinal T2W Transverse Peri-pubescent boys Present as Painless Rapidly growing Very large mass Age related propensity for nodal spread age Unusual < 10 years age ~ 50% > 10 years age
Thoracic and Abdominal RMS All Unfavorable Sites Perineal-perianal area Trunk Abdominal wall Chest wall Paraspinal tissues Retroperitoneum Peritoneum Biliary tract Intrathoracic T1 C+ T1 C+
Perineal/Perianal RMS T1W C+ T1W C+ Very young; < 4.5 years age May mimic polyp or abscess Typically alveolar High incidence of nodal spread
Biliary RMS T1W C+ T1W C+ 2 nd most common cause of obstructive jaundice in very young Arise in liver, bile ducts or gallbladder Solid and cystic mass Biliary ductal dilatation Often present with spread to liver, retroperitoneum, lungs
Extremity Sites Unfavorable All sites unfavorable Includes shoulder/hip girdles Lymphatic spread common Courtesy Dr. Sheri Spunt, St. Jude Children s Research Hospital
Alveolar RMS T1W C+ T1W STIR
Nodal Spread
Alveolar RMS STIR STIR T2W
Diffuse Marrow Metastases
Non-rhabdomyosarcomas The most common pediatric Fibrosarcoma Malignant peripheral nerve sheath tumor Synovial sarcoma
Fibrosarcoma Infantile and adolescent Infantile Better prognosis Metastasis rare Extremity (71%) Trunk (29%) Rapidly growing T1W C+
Malignant Peripheral Nerve Sheath Tumor (MPNST) 50%-80% sporadic 20%-50% in NFI 2%-13% NF1 patients develop MPNST Arise in large/mid size nerves Extremity (33%-46%) Trunk (34%-41%) Head and neck (17%-25%) Target sign on MRI MPNST T2W T2W Benign neurofibromas (target lesions)
Synovial Sarcoma Lower extremity (62%) Upper extremity (21%) Abdomen (7%) Head and neck (3%) Near a joint Often cystic, sharply defined T1W C+ T1W C+