Soft Tissue Tumors
Introduction to Soft Tissue Tumors
- soft tissue = complex of non-epithelial extraskeletal structures of the body
- soft tissue includes: fibrous (Connective) tissue, adipose tissue, skeletal muscle, blood and lymph vessels, and peripheral nerves
- Derivation of most of the soft tissue – mesoderm
- Exception – neuroectodermal for peripheral nerves
- Age has a bearing on type of soft tissue tumor
- Prognosis related to: tumor size, depth, microscopic type & grade, surgical margins, clinical stage…
Tumors of Fibrous Tissue – Fibroma, Fibrosarcoma
Fibroma
- benign
- most common site – ovaries
- GROSS – encapsulated small and firm
- MICRO – spindled fibroblasts with intervening collagen; rare mitoses
Fibrosarcoma
- Malignant
- Arise from superficial and deep connective tissue
- Usually slow growing, painless
- GROSS: usually unencapsulated, infiltrative
- MICRO: spindle cells arranged in intersecting fasicles (“herring bone” pattern); uniform fibroblasts, mitoses present and some are atypical
- Increased mitotic activity and increased cellularity are associated with increased incidence of mets.
- Diagnosis of exclusion
Fibrohistiocytic Tumors – Benign Fibrous Histiocytoma, Malignant Fibrous Histiocytoma
Benign Fibrous Histiocytoma
- slow growing, painless
- occurs in dermis or subcutaneous tissue mostly on extremities
- MICRO: variable mixture of histiocyte-like cells and fibroblast-like cells; rare mitoses
Malignant Fibrous Histiocytoma (MFH)
- Most common sarcoma of adults
- Most common malignant soft tissue tumor
- Morphological variants
1) Storiform-pleomorphic
Ø most common MFH
Ø most common post-irradiation sarcoma
Ø located in the deep soft tissues of the extremities
Ø MICRO: mixture of cells, highly pleomorphic tumor cells in storiform pattern, inflammatory cells, atypical mitoses present
Ø Behavior: local recurrence and mets
2) Myxoid MFH
Ø myxoid = resembling mucus
Ø cellular areas typical of MFH interspersed with myxoid stroma
Ø better prognosis than storiform-pleomorphic
3) Inflammatory MFH
Ø tumor cells mixed with inflammatory cells
Tumors of Adipose Tissue – Lipoma, Liposarcoma
Lipoma
- benign
- most frequent soft tissue tumor
- can occur in any location that fat is present
- GROSS:
Ø bright yellow fat separated by fine fibrous trabeculae
Ø encapsulated in superficial soft tissues
Ø poorly circumscribed in deeper locations
- MICRO
Ø lobules of mature adipocytes separated by thin fibrous septa
Ø angiolipoma, fibrolipoma, mylipoma
Liposarcoma
- malignant
- 2nd most common soft tissue sarcoma in adults
- occur in deep soft tissues
- GROSS: well circumscribed, unencapsulated
- MICRO
Ø lipoblast – mono/multinucleated cell, nucleus is pushed to side by cytoplasmic fat vacuoles giving it a scalloped appearance
- if well differentiated or myxoid type – low grade with recurrence
Tumors of Smooth Muscle- Leiomyoma, Leiomyosarcoma
Leiomyoma
- benign
- most of them occur in female genital tract
- GROSS: well circumscribed, firm, white, whorled
- MICRO: spindle shaped smooth muscle cells with ovoid, blunt ended nuclei; rare mitoses
Leiomyosarcoma
- usually occurs in adults and elderly
- most commonly arise in female genital tract
- GROSS: larger and softer than leiomyoma, hemorrhage and necrosis present
- MICRO: spindle cells in fascicles, mitoses, necrosis
- Prone to recur and often metastasize to liver and lungs
Tumors of Blood Vessels – Hemangioma, Angiosarcoma
Hemangioma
- benign
- true neoplasm vs. muscular malformation
- Capillary Hemangioma (Strawberry nevus)
Ø most common type
Ø present at birth or within first month
Ø regress after 6 months
- Cavernous hemangioma (port-wine nevus)
Ø mainly in children
Ø present at birth
Ø slow growing, does not regress
Ø associated with other syndromes
1) Kasabach-Merritt Syndrome (thrombocytopenia purpura)
2) Maffucci’s Syndrome (multiple endochondromas)
Angiosarcoma
- Malignant
- Arises from the endothelial cells of blood vessels
- Usually occurs in the elderly
- Very aggressive
- Usually located in the skin and subQ of head and neck, breast, bone, liver, spleen
- GROSS: hemorrhagic, deeply invasive
- MICRO
Ø irregularly shaped anastomosing vascular channels
Ø deceptively bland to atypical endothelial lining cells
Ø mitoses present
- usually poor prognosis
Synovial Sarcoma
- uncommon
- usually occur in younger aged
- rarely involves the synovial membrane
- GROSS: well circumscribed, firm, gray-pink
- MICRO: biphasic pattern
1) Epithelial component
2) Spindle cell component
- may recur and metastasize
Granular Cell Tumor
- usually benign
- can occur at any age
- usually located in the tongue
- GROSS: vary from well-circumscribed to infiltrative; small, firm, gray-white
- MICRO: nest and sheets of round or polygonal cells, eosinophilic granular cytoplasm
Tumor Like Conditions – Fibromatoses, Myositic ossificans
Fibromatoses
- group of related conditions
- common threads
1) proliferation of well differentiated fibroblasts/myofibroblasts
2) infiltrative growth pattern
3) variable amounts of collagen between the proliferating cells
4) lack cytologic features of malignancy
5) repeated local occurences but lack capacity to metastasize
- Palmar, Plantar, and Penile fibromatosis
Ø nodular aggregates of mature fibroblasts in dense collagen
Ø Palmar pattern (Dupuytren’s contractures)
Ø Penile fibromatosis – Peyronie’s disease
Myositis Ossificans
- not a tumor
- reactive condition that usually occurs in athletic adolescents and young adults
- initial pain, tenderness, swelling, then painless, hard mass
- XR: soft tissue calcification with radiolucent center
- MICRO
Ø “zonal phenomenon”
Ø central cellular area of fibroblast proliferation
Ø intermediate zone of osteoid formation
Ø peripheral shell of organized bone
- usually cured by simple excision
Tags: Angiosarcoma, Benign Fibrous Histiocytoma, Fibroma, Fibromatoses, Fibrosarcoma, Granular Cell Tumor, Hemangioma, Leiomyoma, Leiomyosarcoma, Lipoma, Liposarcoma, Malignant Fibrous Histiocytoma, Myositis Ossificans, Synovial Sarcoma, tumors
