Soft Tissue Tumors

Lucy H. Liu, M.D.Department of Pathology

University of Illinois at Chicagoe-mail: lucyliu@uic.edu

Soft Tissue Tumors

UIC College of MedicineM2 Pathology Course, Lecture # 63

Tuesday, January 28, 200311:30 am

Soft Tissue Tumors

Lecture Goals:

1. Nomenclature & classification system of tumors

2. Differences between benign and malignant tumors

3. Clinical & morphologic features of common tumors

4. Approach to diagnosis of soft tissue tumors

Soft Tissue Tumor

Neoplastic conditions arising in extraskeletal mesodermal tissues

-- Skeletal muscle

-- Fibrous tissue-- Smooth muscle

-- Blood & lymphatic vessels-- Peripheral nerves - neuroectoderm

-- Adipose tissue

Soft Tissue TumorGeneral principles for diagnosis:

-- Deep lesions tend to be malignant

-- Larger tumors tend to be malignant

Location

Size

-- Superficial lesions - benign

-- Rapidly growing - malignant

Growth pattern

-- Infiltrating - malignant

Metastasis-- Malignant

Soft Tissue Tumors

Histological morphologyImmunohistochemistryCytogenetic studyMolecular analysisUltrastructure

Approach to Diagnosis

Soft Tissue Tumors

Cytokeratin Vimentin Smooth muscle actin Desmin S-100 CD 31 CD 34

Immunohistochemistry

Soft Tissue Tumors

t( 2:13) Alveolar rhabdomyosarcoma t( 11;22) Ewing’s sarcoma/PNET t( 11;22) Desmoplastic small round cell tumor t( 12;16) Myxoid liposarcoma t( 9;22) Myxoid chondrosarcoma t(12;22) Clear cell sarcoma t( X;18) Synovial sarcoma

Cytogenetic Changes

Nodular Fasciitis Benign reactive soft tissue lesion Probably secondary to trauma On forearm, trunk, back- well circumscribed Spindle cells ( fibroblasts & myofibroblasts) in loose matrix -“fibroblasts in tissue culture” Rapid growth, frequent mitotic figures Self-limited, cured by excision Must differentiate from a sarcoma

Nodular Fasciitis

Fibromatosis

Fibroproliferative lesions

Desmoid - Infiltrative masses in abdominal, extra-abdominal & intra-abdominal

Fibroblasts & Myofibroblasts

Palmar, plantar fibromatosis Surgical excision

Infiltrative growth pattern Tendency to recur

Fibromatosis

Fibrosarcoma Malignant tumor of fibroblast origin In adults, in lower extremities, upper extremities, trunk

Increased cellularity, high nuclear-cytoplasmic ratios

Spindle cells in a herringbone pattern

Must exclude other tumors which resemble fibrosarcoma

- Peripheral nerve sheath tumor- Synovial sarcoma

Fibrosarcoma

Dermatofibroma

Benign fibrous histiocytoma

Usually in skin

Mixture of fibroblasts, myofibroblasts, histiocytesSurgical excision

Dermatofibroma

Dermatofibrosarcoma Protuberans (DFSP)

Fibrohistiocytic tumor Intermediate malignant potential In skin & subcutis Spindle cells in storiform pattern Local recurrence CD 34 Transformation to fibrosarcoma Surgical excision

Dermatofibrosarcoma Protuberans ( DFSP )

Malignant Fibrous Histiocytoma

Malignant soft tissue tumor with histocytic differentiationMost common type of soft-tissue sarcomaMost frequently encountered sarcoma post radiation therapyIn adults, in deep soft tissue - extremities & retroperitoneumMarked pleomorphism, spindle cells, storiform, myxoid

MFH

Leiomyoma

Benign soft tissue tumor

Arising in subcutaneous tissue or blood vessel wall Usually painful

Fascicles of regular smooth muscle cells

Leiomyoma

Leiomyosarcoma Malignant soft tissue tumor Arising in extremities of blood vessel wall Necrosis, hemorrhage Fascicles, nuclear atypia High mitotic activity

Leiomyosarcoma

Rhabdomyosarcoma

Malignant tumor of striated muscle differentiation In children & young adults Several subtype

- Embryonal - Alveolar - Botryoid- Pleomorphic

Embryonal Rhabdomyosarcoma

Most common in children, in head & neck Most common subtype Rhabdomyoblasts with cytoplasmic cross-striation

Embryonal rhabdomyosarcoma

Botryoid Rhabdomyosarcoma

Most common in hollow visceral organs - genitourinary tract

Polypoid, grape-like tumor masses

Scattered malignant cells in myxoid stroma

Botryoid rhabdomyosarcoma

Alveolar Rhabdomyosarcoma

In extremities

Fibrous septa with loose clusters of rounded cells in center

- alveolar pattern

Alveolar rhabdomyosarcoma

Pleomorphic Rhabdomyosarcoma

In skeletal muscles of older persons, in thigh

Marked pleomorphism

Irregularly arranged cells

Multinucleated giant cells

Pleomorphic Sarcoma

Lipoma Benign, well-circumscribed tumor of well-differentiated adipocytes

Usually subcutaneous, any site of adipose tissue Most common type of benign soft tissue tumor

In adult, upper back, neck, shoulder

Resemble normal adipose tissue Subtypes:angiolipoma, spindle cell lipoma

Lipoma

Liposarcoma Second most common sarcoma in adults

In deep compartments of extremities & retroperitoneum Lipoblasts Several subtypes- Well differentiated/atypical

lipoma- Myxoid / Round cell- Pleomorphic

Liposarcoma

Hemangioma

Benign lesion Resemble normal blood vessels Congenital or non-congenital Most common in infants & children Head & neck, internal organs - liver

Angiosarcoma

Malignant vascular tumor Many locations: skin, soft tissue, breast, live, spleen Irregular channels & atypical endothelial cells CD31- endothelial cell marker

Angiosarcoma

Schwannoma

Benign tumor of neural differentiation - Schwann cells

Antoni A

Antoni B

In association with large nerve trunks Head & neck, extremities

-- Cellular area, palisaded nuclei

-- Less cellular area, myxoid background S-100

Schwannoma

Synovial sarcoma Malignant soft tissue tumor

Arising in region of a joint & other sites of deep soft tissue

Unknown origin- misnomer

Multilobular Biphasic pattern

- spindle cells- epithelial - like cells

t( X;18 )

Synovial sarcoma