(Roll no 135-139)
135-UMR.AKANKSHA
(WHO classification of soft tissue tumours)
136-DEDEEPYA VEMURI
(Etiopaghogenesis of soft tissue tumours)
137-UJWALA
(Gross features of soft tissue tumours)
138-VAGISHA RANI
(Microscopy of soft tissue tumours)
139-VAMSHITHA
(Genetics of soft tissue tumours)
Topic-1
World Health Organization classification of soft-tissue tumors
The World Health Organization (WHO) issued an updated classification of soft-tissue tumors that divided them into the following categories.
- Adipocytic tumors
- Fibroblastic/myofibroblastic tumors
- So-called fibrohistiocytic tumors
- Smooth-muscle tumors
- Pericytic (perivascular) tumors
- Skeletal-muscle tumors
- Vascular tumors
- Chondro-osseous tumors
- Gastrointestinal stromal tumors
- Nerve-sheath tumors
- Tumors of uncertain differentiation
- Undifferentiated/unclassified sarcomas
In addition, as part of this classification, soft tissue tumors were divided into the following four categories as appropriate:
- Benign
- Intermediate (locally aggressive)
- Intermediate (rarely metastasizing)
- Malignant
This terminology should not be confused with the grading system mentioned above, in which grade 2 may be regarded as intermediate.
Adipocytic tumors
Benign adipocytic tumors include the following:
- Lipoma
- Lipomatosis
- Lipomatosis of nerve
- Lipoblastoma/lipoblastomatosis
- Angiolipoma
- Myolipoma
- Chondroid lipoma
- Extrarenal angiomyolipoma
- Extra-adrenal myelolipoma
- Spindle cell/pleomorphic lipoma
- Hibernoma
Intermediate (locally aggressive) adipocytic tumors include the following:
- Atypical lipomatous tumor/well-differentiated liposarcoma
Malignant adipocytic tumors include the following:
- Dedifferentiated liposarcoma
- Myxoid liposarcoma
- Pleomorphic liposarcoma
- Liposarcoma, not otherwise specified
Fibroblastic/myofibroblastic tumors
Benign fibroblastic/myofibroblastic tumors include the following:
- Nodular fasciitis
- Proliferative fasciitis
- Proliferative myositis
- Myositis ossificans
- Fibro-osseous pseudotumor of digits
- Ischemic fasciitis
- Elastofibroma
- Fibrous hamartoma of infancy
- Fibromatosis colli
- Juvenile hyaline fibromatosis
- Inclusion body fibromatosis
- Fibroma of tendon sheath
- Desmoplastic fibroblastoma
- Mammary-type myofibroblastoma
- Calcifying aponeurotic fibroma
- Angiomyofibroblastoma
- Cellular angiofibroma
- Nuchal-type fibroma
- Gardner fibroma
- Calcifying fibrous tumor
Intermediate (locally aggressive) fibroblastic/myofibroblastic tumors include the following:
- Superficial fibromatoses - Palmar/plantar
- Desmoid-type fibromatoses
- Lipofibromatosis
- Giant cell fibroblastoma
Intermediate (rarely metastasizing) fibroblastic/myofibroblastic tumors include the following:
- Dermatofibrosarcoma protuberans - Fibrosarcomatous, pigmented
- Solitary fibrous tumor - Solitary fibrous tumor, malignant
- Inflammatory myofibroblastic tumor
- Low-grade myofibroblastic sarcoma
- Myxoinflammatory fibroblastic sarcoma/atypical myxoinflammatory fibroblastic tumor
- Infantile fibrosarcoma
Malignant fibroblastic/myofibroblastic tumors include the following:
- Adult fibrosarcoma
- Myxofibrosarcoma
- Low-grade fibromyxoid sarcoma
- Sclerosing epithelioid fibrosarcoma
So-called fibrohistiocytic tumors
Benign tumors of this type include the following:
- Tenosynovial giant cell tumor - Localized, diffuse, malignant
- Deep benign fibrous histiocytoma
Intermediate (rarely metastasizing) tumors of this type include the following:
- Plexiform fibrohistiocytic tumor
- Giant cell tumor of soft tissues
Smooth-muscle tumors
These tumors include the following:
- Benign - Leiomyoma of deep soft tissue
- Malignant - Leiomyosarcoma (excluding skin)
Pericytic (perivascular) tumors
These tumors include the following:
- Glomus tumor (and variants) - Glomangiomatosis, malignant glomus tumor
- Myopericytoma - Myofibroma, myofibromatosis
- Angioleiomyoma
Skeletal-muscle tumors
These tumors include the following:
- Rhabdomyoma
- Embryonal rhabdomyosarcoma
- Alveolar rhabdomyosarcoma
- Pleomorphic rhabdomyosarcoma
- Spindle cell/sclerosing rhabdomyosarcoma
Vascular tumors
Benign vascular tumors include the following:
- Hemangioma - Synovial, venous, arteriovenous hemagnioma/malformation
- Epithelioid hemangioma
- Angiomatosis
- Lymphangioma
Intermediate (locally aggressive) vascular tumors include the following:
- Kaposiform hemangioendothelioma
Intermediate (rarely metastasizing) vascular tumors include the following:
- Retiform hemangioendothelioma
- Papillary intralymphatic angioendothelioma
- Composite hemangioendothelioma
- Pseudomyogenic (epithelioid sarcoma-like) hemangioendothelioma
- Kaposi sarcoma
Malignant vascular tumors include the following:
- Epithelioid hemangioendothelioma
- Angiosarcoma of soft tissue
Chondro-osseous tumors
These tumors include the following:
- Soft-tissue chondroma
- Mesenchymal chondrosarcoma
- Extraskeletal osteosarcoma
Gastrointestinal stromal tumors
Gastrointestinal stromal tumors (GISTs) include the following:
- Benign GIST
- GIST of uncertain malignant potential
- Malignant GIST
Nerve-sheath tumors
Benign nerve-sheath tumors include the following:
- Schwannoma (including variants)
- Melanotic schwannoma
- Neurofibroma (including variants) - Plexiform neurofibroma
- Perineurioma - Malignant perineurioma
- Granular cell tumor
- Dermal nerve sheath myxoma
- Solitary circumscribed neuroma
- Ectopic meningioma
- Nasal glial heterotopia
- Benign Triton tumor
- Hybrid nerve-sheath tumors
Malignant nerve-sheath tumors include the following:
- Malignant peripheral nerve sheath tumor
- Epithelioid malignant nerve sheath tumor
- Malignant Triton tumor
- Malignant granular cell tumor
- Ectomesenchymoma
Tumors of uncertain differentiation
Benign tumors of uncertain differentiation include the following:
- Acral fibromyxoma
- Intramuscular myxoma (including cellular variant)
- Juxta-articular myxoma
- Deep ("aggressive") angiomyxoma
- Pleomorphic hyalinizing angiectatic tumor
- Ectopic hamartomatous thymoma
Intermediate (locally aggressive) tumors of uncertain differentiation include the following:
- Hemosiderotic fibrolipomatous tumor
Intermediate (rarely metastasizing) tumors of uncertain differentiation include the following:
- Atypical fibroxanthoma
- Angiomatoid fibrous histiocytoma
- Ossifying fibromyxoid tumor - Including malignant
- Mixed tumor NOS - Including malignant
- Myoepithelioma
- Myoepithelial carcinoma
- Phosphaturic mesenchymal tumor - Benign, malignant
Malignant tumors of uncertain differentiation include the following:
- Synovial sarcoma NOS - Spindle cell, biphasic
- Epithelioid sarcoma
- Alveolar soft-part sarcoma
- Clear cell sarcoma of soft tissue
- Extraskeletal myxoid chondrosarcoma
- Extraskeletal Ewing sarcoma
- Desmoplastic small round cell tumor
- Extrarenal rhabdoid tumor
- Neoplasms with perivascular epithelioid cell differentiation (PEComa)
- Intimal sarcoma
Undifferentiated/unclassified sarcomas
These tumorsinclude the following:
- Undifferentiated spindle cell sarcoma
- Undifferentiated pleomorphic sarcoma
- Undifferentiated round cell sarcoma
- Undifferentiated epithelioid sarcoma
- Undifferentiated sarcoma NOS
Benign vs intermediate vs malignant tumors
Benign soft-tissue tumors usually do not recur locally, and if they do, the recurrence is nondestructive and almost always readily curable by complete local excision. Morphologically benign lesions, which are extremely rare, may give rise to distant metastases, which cannot be predicted on the basis of routine, contemporary histologic evaluation. This is best documented in rare, cutaneous benign fibrous histiocytoma.
Intermediate (locally aggressive) soft-tissue tumors show an infiltrative and locally destructive growth pattern. However, although they may recur locally, they do not metastasize. They usually require excision with a wide margin of normal tissue for better local control. The example in this category is desmoid (fibromatosis).
Intermediate (rarely metastasizing) soft-tissue tumors are often locally aggressive, but in some cases, they also have a tendency to produce distant metastases (usually in a lymph node or lung). This risk is low (< 2%), but histomorphologically, it is not reproducibly predictable. The classic examples in this group are plexiform fibrohistiocytic tumor and angiomatoid fibrous histiocytoma.
Malignant soft-tissue sarcomas are locally destructive with the potential to recur. The risk of distant metastasis is significant. (Depending on histologic type and grade, the potential ranges from 20% to almost 100%). Histologically low-grade sarcomas have a lower chance of metastasis (only 2-10%). However, the recurrences of such tumors may advance in grade and attain a higher risk of metastatic potential similar to that associated with myxofibrosarcoma and leiomyosarcoma.
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