Miller-Soft tissue tumors Flashcards
Soft tissue tumor introduction
Soft tissue tumors are common. They may appear as painless small lumps or large masses.
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Soft tissue tumors can be broadly classified as benign or malignant (sarcoma) or characterized by reactive tumorlike conditions.
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Lesions are further classified according to composition; for example, whether they tend to produce collagen (fibrous lesion), fat, or vascular tissue.
What are the soft tissue tumors with lymph node metastasis?
ESARC
Review malignant soft tissue tumors
Presentation
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Masses are deceptively painless and commonly are inappropriately assumed to be lipomas.
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A mass that is more than 5 cm, growing, and deep to the superficial fascia should be presumed to be a soft tissue sarcoma (STS) until proven otherwise, and it should be assessed with three-dimensional imaging first (ideally MRI).
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Patients often experience enlarging painless or painful soft tissue masses.
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In some instances, the masses are small and may be present for a long time before they are recognized as tumors
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Imaging
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MRI is the best imaging modality for defining the anatomy of and helping characterize the lesion.
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MRI provides information on tumor size, grade, depth, and anatomic location and aids in surgical planning.
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On T1-weighted images, STSs have a high signal intensity (isointense with muscle), and on T2-weighted images, they have a low signal intensity.
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With the administration of intravenous gadolinium contrast agent, an STS typically demonstrates a peripheral enhancing zone and a nonenhancing, necrotic center.
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CT of the chest is performed to evaluate for metastasis.
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Treatment
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Radiation therapy is an important adjunct to surgery in the treatment of soft tissue sarcomas.
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External beam irradiation can be delivered preoperatively or postoperatively with the same oncologic outcome.
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Intensity-modulated radiation therapy (IMRT) is a common type of external beam radiation therapy used for soft tissue sarcomas.
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Other features
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In the United States, approximately 12,000 new cases of soft tissue sarcoma are diagnosed each year.
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Poor prognostic factors include the presence of metastases, high histologic grade, and size greater than 5 cm. Unplanned removal of a soft tissue sarcoma is the most common error in treatment of STSs.
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Residual tumor may exist at the site of the operative wound, and in all patients with an unplanned removal, repeat excision should be performed.
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Delay in diagnosis may also occur if the clinician does not recognize that the lesion is malignant.
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Metastasis: Most soft tissue sarcomas metastasize to the lung.
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Lymph node metastasis occurs with 5% of soft tissue sarcomas.
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Epithelioid sarcoma, synovial sarcoma, angiosarcoma, rhabdomyosarcoma, and clear cell sarcoma (mnemonic: ESARC) are the tumors that most commonly metastasize to the lymph nodes (Table 9.17
Review MFH or
UPS
Undifferentiated pleomorphic sarcoma (UPS; previously malignant fibrous histiocytoma).
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Histology: The spindle and histiocytic cells are arranged in a storiform (cartwheel) pattern. Short fascicles of cells and fibrous tissue appear to radiate about a common center around slitlike vessels. Chronic inflammatory cells may also be present.
Review Fibrosarcoma
Fibrosarcoma
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Histology: There is a fasciculated growth pattern, with fusiform or spindle-shaped cells, scanty cytoplasm, and indistinct borders, and the cells are separated by interwoven collagen fibers. There is a herringbone pattern, which consists of intersecting fascicles in which the nuclei in one fascicle are aligned transversely but in an adjacent fascicle are aligned longitudinally.
Review Malignant Peripheral Nerve Sheet tumor
MPNST
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Histology: Spindle cells arranged in sweeping fascicles, with areas of nodular and whorled appearance. Immunohistochemistry shows S-100 positivity.
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Other features: Tumor may arise de novo or in the setting of neurofibromatosis.
Review Leiomyosarcoma
Leiomyosarcoma
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Histology: Fascicular growth pattern with spindle cells that intersect at right angles; IHC: positivity for SMA and desmin.
Review Angiosarcoma
Angiosarcoma
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Histology: Cells resemble endothelium of blood vessels.
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Other features
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Highly malignant
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Lymph node and cutaneous metastases are common (ESARC).
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Infiltrative with poor margins; amputation may be necessary to achieve local control.
Review Liposarcoma
Liposarcoma
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Presentation: Liposarcomas rarely occur in the subcutaneous tissues.
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Histology: Heterogeneous group of tumors, having in common the presence of lipoblasts (signet ring–shaped cells)
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Other features
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They are classified into the following types:
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Well-differentiated liposarcoma (low grade) (Fig. 9.6 in Table 9.18)
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Lipomalike
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Sclerosing
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Inflammatory
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Myxoid liposarcoma (intermediate grade)
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Dedifferentiated (high grade) (Fig. 9.7 in Table 9.18)
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Round cell liposarcoma (high grade)
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Pleomorphic liposarcoma (high grade)
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Liposarcomas metastasize according to the grade of the lesion.
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Well-differentiated liposarcomas have a very low rate of metastasis (<10%).
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The metastasis rate of intermediate-grade liposarcomas is 10%–30%.
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The metastasis rate of high-grade liposarcomas is more than 50%
Review Rhabdomyosarcoma
Rhabdomyosarcoma
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Presentation
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Rapidly growing soft tissue mass in a patient less than 30 years old
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The most common sarcoma in young patients
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Histology
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Racquet-shaped cells and cross-striations within the tumor cells (rhabdomyoblasts); IHC: positivity for myogenin and MyoD1
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Treatment: Rhabdomyosarcomas are sensitive to multiagent chemotherapy and wide-margin surgical resection after chemotherapy. External beam irradiation may also also used.
Review Synovial Sarcoma
Synovial sarcoma
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Presentation
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May be present for years or may manifest as a rapidly enlarging mass in patients less than 30 years of age
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Synovial sarcoma is the most common sarcoma in the foot.
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Imaging
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Radiographs or CT may show mineralization within the lesion in up to 25% of cases (spotty mineralization may even resemble the peripheral mineralization seen in heterotopic ossification).
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Histology
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The tumor is often biphasic, with both epithelial and spindle cell components. It may be monophasic with spindle cells only.
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The epithelial component may show epithelial cells that form glands or nests, or they may line cystlike spaces.
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IHC: Positivity for keratin and epithelial membrane antigen (EMA)
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Genetics
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Translocation between chromosome 18 and the X chromosome—t(X;18)—is always present in tumor cells, and staining of the tumor cells yields positive results for keratin and EMA.
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The balanced translocation results in gene fusion products. The two most common are SYT-SSX1 and SYT-SSX2.
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Treatment
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Wide surgical resection with adjuvant radiotherapy (XRT) is the most common method of treatment.
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Synovial sarcoma is an unusual soft tissue sarcoma in which chemotherapy has shown a clinical benefit.
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Other features
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Lymph nodes may be involved (ESARC).
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The name is derived from the histologic appearance, not from origination from the synovium. This is not an intraarticular tumor
Review Epitheliod Sarcoma
Epithelioid sarcoma
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Presentation
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Rare nodular tumor that commonly occurs in the upper extremities of young adults
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The most common sarcoma of the hand
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Histology: Cells range in shape from ovoid to polygonal, with deeply eosinophilic cytoplasm (cellular pleomorphism is minimal).
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Treatment: Wide-margin surgical resection
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Differential diagnosis: Granuloma, rheumatoid nodule, or inclusion cyst. Often misdiagnosed as benign process.
Review Clear Cell Sarcoma
Clear cell sarcoma
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Presentation
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Slow-growing mass in association with tendons or aponeuroses
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Usually occurs about the foot and ankle but may also involve the knee, thigh, or hand
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Histology: Characterized by compact nests or fascicles of rounded or fusiform cells with clear cytoplasm; multinucleated giant cells are common.
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Treatment: Wide-margin surgical resection with adjuvant radiation
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Other features: Metastases to lymph nodes (ESARC)
Review Dermatofibrosis Protuberans
Dermatofibrosarcoma protuberans
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Presentation
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Rare, nodular, cutaneous tumor that occurs in early to middle adulthood
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A low-grade tumor with a tendency to recur locally that rarely metastasizes
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Histology: The central portion of the nodules shows uniform fibroblasts arranged in a storiform pattern around an inconspicuous vasculature.
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Treatment: Wide-margin surgical resection, which may require skin grafting
Review Fibromatosis
Fibromatosis
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Palmar (Dupuytren) and plantar (Ledderhose) fibromatoses: These disorders consist of firm nodules of fibroblasts and collagen that develop in the palmar and plantar fascia. The nodules and fascia become hypertrophic, producing contractures.
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Extraabdominal desmoid tumor; most locally invasive of all benign soft tissue tumors.
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Presentation
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Commonly occurs in adolescents and young adults
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Patients with Gardner syndrome (familial adenomatous polyposis) have colonic polyps and a 10,000-fold increased risk for development of desmoid tumors.
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On palpation, the tumor has a distinctive “rock-hard” character.
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Multiple lesions may be present in the same extremity (10%–25%).
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Histology:
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Well-differentiated fibroblasts and abundant collagen. The lesion infiltrates adjacent tissues.
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IHC: Positivity for estrogen receptor β and β-catenin
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Treatment
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Medical management including NSAIDS, tamoxifen, and cytotoxic chemotherapy
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Behavior of the tumor is unpredictable: Recurrent nodules may remain dormant for years or may grow rapidly for some time and then stop growing, especially in pregnancy because of the high level of circulating estrogen.
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Nodular fasciitis
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Presentation: A common reactive lesion that manifests as a painful, rapidly enlarging mass in the upper extremity of a young person less than 30 years old
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Histology: Short, irregular bundles and fascicles; a dense reticulum network; and only small amounts of mature collagen characterize the lesion histologically. Mitotic figures are common, but atypical mitoses are not a feature.
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Treatment: Wide marginal excision
