What it is (overview)

A soft tissue biopsy with imaging guidance is a minimally invasive diagnostic procedure in which a clinician removes a small tissue sample from an area of concern in muscles, fat, fascia, tendons/ligaments, or soft-tissue masses. The biopsy is performed while using imaging guidance—most commonly ultrasound or a CT scan—to accurately place the needle into the target. Imaging guidance helps the provider avoid nearby nerves and blood vessels and improves the chance of collecting the most informative tissue.

This test does not “measure” a number like a blood test. Instead, the tissue sample is examined by a pathologist under a microscope and may also be tested with special stains, cultures, and molecular tests. Results typically describe what the tissue is made of and whether abnormal cells are present.

In plain language, the results often fall into categories such as:

Benign (non-cancerous) findings: The tissue may show a non-cancerous growth (such as a lipoma), scar tissue, or reactive changes. This can help avoid unnecessary surgery and guide monitoring.

Malignancy (cancer) or suspected cancer: The biopsy may confirm a tumor diagnosis (for example, sarcoma or metastatic cancer) and may provide details that guide treatment (such as tumor type, grade, and markers).

Infection: The sample may show infection and, when culture is performed, may identify the specific bacteria, fungus, or other organism to help choose the most effective antibiotic or antifungal medication.

Inflammation or autoimmune-related changes: The tissue may show inflammatory patterns consistent with conditions like inflammatory myositis, vasculitis, or granulomatous disease, helping direct further testing and treatment.

Non-diagnostic/insufficient sample: Occasionally, the sample does not contain enough representative tissue. In that case, a repeat biopsy (sometimes with a different approach or imaging method) may be recommended.

When & why it's usually done

A healthcare provider may recommend an imaging-guided soft tissue biopsy when imaging (such as ultrasound, CT, or MRI) shows a lump, mass, or area of abnormal tissue and a diagnosis is needed to plan next steps. It is commonly chosen because it can provide answers without requiring a larger open surgical procedure.

This biopsy procedure is often ordered when a person has:

A new or growing lump in the arm, leg, trunk, neck, or near a joint—especially if it is firm, deep, larger than expected, or increasing in size.

Persistent pain, swelling, or tenderness in a specific soft-tissue area, particularly when symptoms last weeks or do not improve with usual care.

Unexplained inflammation seen on imaging or lab work, such as swelling of a muscle group or soft tissue thickening.

Concern for infection (for example, a suspected abscess or infected fluid collection), especially in people with fever, elevated inflammatory markers, diabetes, immune suppression, recent surgery, or a history of injections/trauma to the area.

History of cancer with a new soft tissue mass that could represent spread (metastasis) or a new primary tumor.

Need to confirm a diagnosis before treatment, such as deciding between observation, antibiotics, surgery, radiation, chemotherapy, or other targeted therapies.

Imaging guidance is selected based on location and visibility of the target. Ultrasound-guided biopsy is often used for superficial or easily visualized masses and allows real-time needle placement without radiation. CT-guided biopsy is helpful for deeper lesions or areas difficult to reach, such as near the pelvis, retroperitoneum, or deep muscle compartments.

Common diseases related to it

• Soft tissue sarcoma (malignant soft tissue tumor)
• Metastatic cancer to soft tissues (spread from another primary cancer)
• Benign soft tissue tumors (e.g., lipoma, benign peripheral nerve sheath tumor)
• Desmoid tumor (aggressive fibromatosis)
• Abscess or deep soft tissue infection
• Cellulitis with suspected deeper involvement
• Necrotizing soft tissue infection (when imaging suggests deep tissue involvement)
• Inflammatory myositis (e.g., polymyositis/dermatomyositis patterns on biopsy)
• Vasculitis affecting soft tissues or muscle
• Granulomatous inflammation (e.g., sarcoidosis or certain infections)
• Hematoma or organizing blood collection that mimics a mass

Health goals where it may help

• Getting an accurate diagnosis of a soft tissue lump or mass to guide a safe treatment plan
• Ruling out cancer or confirming a tumor diagnosis early to improve treatment options
• Identifying an infection and supporting targeted antibiotic/antifungal therapy
• Clarifying the cause of unexplained inflammation to guide specialist care (e.g., rheumatology, infectious disease, oncology)
• Supporting care planning before surgery, radiation therapy, or chemotherapy by confirming tissue type
• Reducing unnecessary procedures by distinguishing benign from serious conditions
• Monitoring overall health decision-making through timely follow-up and appropriate referrals within healthcare