Soft Tissue Neoplasms

Soft Tissue Neoplasms
Definition

  • Soft Tissue: All non-epithelial tissue arising from mesodermal derivatives, excluding:

    • Bone

    • Cartilage

    • Brain and coverings

    • Hematopoietic cells

    • Lymphoid tissue

Classification
1. Benign Tumors (more common)

  • Adipose Tissue: Lipoma

  • Fibrous Tissue: Keloid, Fibroma, Nodular Fasciitis

  • Fibrohistocytic: Fibrous histiocytoma

  • Muscle Origin: Rhabdomyoma, Leiomyoma

  • Lymphatic System: Cystic hygroma, Lymphangioma simplex, Lymphangioma

  • Vascular System: Hemangioma, Pyogenic granuloma, Glomus body tumor

  • Nervous System: Neuroma, Neurofibroma, Schwannoma

  • Uncertain Origin: Hamartoma

2. Locally Malignant Tumors (do not metastasize)

  • Desmoid tumor

  • Dermatofibrosarcoma protuberans

3. Malignant Tumors (rare)

  • Liposarcoma

  • Fibrosarcoma

  • Malignant fibrous histiocytoma

  • Rhabdomyosarcoma

  • Leiomyosarcoma

  • Lymphangiosarcoma

  • Hemangiosarcoma

  • Malignant Schwannoma

  • Kaposi sarcoma

  • Malignant hamartoma

  • Synovial sarcoma

  • Epithelioid sarcoma

Benign Tumors Details
Lipoma

  • Common soft tissue neoplasm, can occur anywhere with adipose tissue (excludes eyelids, glans penis).

  • Common sites include head & neck, shoulder, abdominal wall, thighs.

  • Usually solitary; can be familial (Dercum disease).

Types of Lipoma

  • Pathological: Pure lipoma, fibrolipoma, hemangiolipoma, angiolipoma (painful).

  • Anatomical: (in decreasing frequency)

    • Subcutaneous

    • Inter-muscular

    • Retroperitoneal

    • Sub-fascial

    • Sub-serous

    • Sub-mucous

    • Sub-synovial

    • Intra-articular

    • Para-osteal

    • CNS

    • Intra-glandular

Clinical Picture

  • History: Slowly growing, painless lump.

  • Examination: Well-defined, smooth/lobulated surface, non-tender, soft, mobile, pseudo-fluctuant.

  • Investigations: FNAC shows benign fat cells; US shows well-circumscribed, capsulated swelling.

  • Differential Diagnosis: Sebaceous cyst, fibroma, organized hematoma, ganglion.

Complications

  • Sarcomatous changes in specific sites (retroperitoneal, back, thigh)

  • Myxomatous degeneration

  • Calcification

  • Pressure effects

Treatment

  • Standard: Excisional biopsy; Liposuction for cosmetic cases.

  • For multiple tumors: Excise symptomatic/complicating one.

Fibroma

  • Rare as pure fibroma; usually combined types: fibromyoma, fibrolipoma, etc.

  • Soft or hard based on proportion of fibrous to cellular tissue.

Neurofibromatosis

  • Genetics: Autosomal dominant (AD).

  • Types:

    • Type 1: Von Recklinghausen disease; characterized by multiple pedunculated nodules & café-au-lait spots.

    • Type 2: Bilateral acoustic neurofibromatosis; presents with pain, numbness, tenderness along nerve axis.

Local Malignant Tumors
Desmoid Tumor

  • Rare tumor from musculo-aponeurotic tissues.

  • Most common site: Anterior abdominal wall, presents as hard mass.

  • Associated with familial polyposis coli (Gardner syndrome).

Pathology

  • Fibrous tissue structure, multinucleated, un-capsulated; infiltrates surrounding muscles.

  • No metastasis or sarcomatous change.

Treatment

  • Wide excision with safety margins; repair muscular defects with prosthetic mesh.

  • Radiotherapy for adjuvant therapy.

Dermatofibrosarcoma Protuberans

  • Intermediate tumor between benign and malignant.

  • Composed of fibroblasts and lipid-laden phagocytes.

  • Clinical Picture: Rare, occurs in young individuals, presents as bluish dermal nodule; sudden growth, ulceration possible.

  • Treatment: Wide local excision.

Soft Tissue Sarcomas (STS)

  • Rare (1% of human cancers), arise from mesenchymal tissue.

  • Histological grading & clinical staging are significant for prognosis.

Characteristics

  • Younger age; rapid growth; higher local invasion; common blood-borne metastasis; worse prognosis.

Etiology

  • Unknown, but include:

    • Radiation exposure

    • Post-mastectomy lymphedema

    • Von Recklinghausen disease

Grading

  • G1: Well differentiated

  • G2: Moderately differentiated

  • G3: Poorly differentiated

  • G4: Undifferentiated

Staging

  • T1: ≤ 5 cm

  • T2: > 5 cm

  • N0: No regional LN metastasis

  • N1: Regional LN metastasis

  • M0: No distant metastasis

  • M1: Distant metastasis

Differential Diagnosis

  • Benign tumors, hematoma, vascular issues, lymphadenopathy, myositis ossificans.

Prognostic Factors

  1. Tumor type: Malignant histiocytoma is the worst.

  2. Grading: Undifferentiated is worse.

  3. Staging: Distant metastases are often fatal.

  4. Site: Retroperitoneal is more fatal.

  5. Local recurrence: Recurrence predisposes further recurrences.

  6. Biological expression of tumor (e.g., p53).

Clinical Picture of STS

  • Rapidly growing, painless swelling, hot surface, ill-defined borders, fixed structure, variable consistency.

Investigations

  1. CT: Best for abdominal/thoracic lesions

  2. MRI: Better for neurological/muscle lesions

  3. PET: Evaluates metabolic functions

  4. Biopsy: Open incisional or FNAC/cored biopsy under imaging guidance preferred.

Treatment

  1. Surgical: En-bloc wide excision including major neurovascular structures if needed. Amputation for aggressive cases. Localized solitary metastases could be excised.

  2. Radiotherapy: Preoperative reduces size; postoperative adjuvant for suspected margin involvement.

  3. Chemotherapy: Best results in childhood malignancies.

Characterization of Specific Tumors

  • Liposarcoma: Most common, occurs in ages 50-60, frequent in retroperitoneal region.

  • Malignant Fibrohistosarcoma: Common in young adults, highly aggressive, >50% recurrence/metastasis rate.

  • Fibrosarcoma: 2nd most common in 35-50 years; firm, rubbery, painless lump, variable grades.

  • Rhabdomyosarcoma: Predominantly in children, good response to treatments.

  • Kaposi Sarcoma: Rare malignancy with skin lesions; two types based on aggressiveness; treatment includes AZT/IFN and limited surgery.

  • Synovial Sarcoma: Comprises 10% of STS, originates from mesenchymal cells; high grade indicates aggressive nature with high recurrence rate.

Retroperitoneal Tumors
Anatomy

  • Retroperitoneal space: Extends from diaphragm to pelvic brim, contains various vital organs and vasculature.

Classification

  • Cystic: Teratoma, others.

  • Solid benign (20%): Lipoma, others.

  • Malignant (80%): Lymphoma, liposarcoma, fibrosarcoma.

Diagnosis

  • Symptoms include abdominal discomfort, back pain, fatigue.

  • Examination may reveal palpable mass causing vascular obstructions.

  • Imaging: CT/MRI as primary tools; CT-guided biopsy essential.

Treatment

  • Surgical excision is standard, but few are resectable. In unresectable cases, de-bulking and combined treatment offer better prognosis than either alone.