Sarcoma – Signs, Histology, and Treatment

Pathophysiology of Soft Tissue Sarcoma

1) sarcomas of the soft tissue are a family of neoplasms affecting the soft tissue of the body Causes 2) previous radiation 3) HIV 4) genetic predisposition such as L-Fraumeni syndrome 5) asbestosis 6) congenital immunodeficiences 7) dioxin exposure 8) Herpes virus

Signs and Symptoms

1) most common presentation is an enlarging mass 2) pain 3) neuralgia and neurologic deficits, if the tumor encases a nerve structure 4) metastases are usually via the blood system and most commonly go to the lungs

Characteristic Test Findings

Radiology – mass on MRI

Histology/Gross Pathology

1) most bone-forming sarcomas can also occasionally arise from soft tissue 2) there are approximately 20 different types of soft tissue sarcomas 3) leiomyomasarcoma – interwoven spindle cells 4) angiosarcoma – highly vascular 5) liposarcoma – prominent lipoblasts 6) malignant fibrous histiocytoma – mixture of round histiocytic cells and fibrous spindle cells in a storiform pattern 7) rhabdomyosarcoma – sheets of homogenous small cells or pleomorphic cells with pink, striated cytoplasm

Biochemistry

1) some tumors have germline abnormalities of tumor-suppressor p53 2) some tumors have germline abnormalities of Rb-1 (chromosome 13) 3) some tumors produce insulin-like growth factor, which acts to promote metastatic spread

Inheritance/Epidemiology

1) 6000 new cases per year in USA 2) rare for benign soft tissues to undergo malignant transformation, except for neurofibromas and malignant peripheral nerve sheath tumors (previously called schwannomas)

Treatment

1) surgery – shelling out mass and capsule in sarcoma surgery is not adequate (requires radical excision, including biopsy site) 2) aggressive resection of lung metastases 3) traditional chemotherapy has been doxorubicin-based 4) many chemotherapy protocols now adding ifosfamide 5) targeted agents such as everolimus used if indicated by molecular profiling of the tumor tissue 6) high dose radiation therapy (approximately 7000 cGy) for local control 7) head and neck soft tissue sarcomas are increasingly being treated with proton therapy in lieu of intensity modulated photon radiation therapy 8) outcomes are reportedly improved with treatment at sarcoma center

Tips for USMLE

if a 24-year-old nurse notices an expanding mass in the subcutaneous tissue of her posterior thigh that has grown to 8 cm in the past year, but is not painful, think soft tissue sarcoma