Solitary Fibrous Tumour (Hemangiopericytoma)

What Is a Solitary Fibrous Tumour (SFT)?

A solitary fibrous tumour is a rare growth that arises from the body's fibrous connective tissue — the mesenchymal cells that form the supporting framework around organs, in the chest lining (pleura), and deep in the soft tissues of the limbs, pelvis and head and neck. Despite the word "fibrous," an SFT is not a scar or a simple fibroid; it is a true neoplasm with its own distinct genetic signature, and it is classified by the World Health Organization alongside the other soft tissue sarcoma subtypes covered on our sarcoma — overview hub.

The name often causes confusion, so it is worth being precise. For decades, pathologists used "hemangiopericytoma" for tumours that appeared to grow around small blood vessels, and "solitary fibrous tumour" for fibrous-looking pleural masses. We now know these are the same tumour seen along a spectrum — the two terms have been merged into a single entity, "solitary fibrous tumour," in the current classification. If your old report says hemangiopericytoma and a newer one says SFT, they are describing the same disease, not a change in your diagnosis.

SFTs can develop almost anywhere. The classic site is the pleura (the lining of the lung), but they are increasingly found in the limbs, the retroperitoneum behind the abdominal organs, the pelvis, and even inside the skull lining (meningeal SFT). Because they are usually slow-growing and painless, many are discovered incidentally on a scan done for another reason, or only when they have grown large enough to press on something.

Symptoms: How a Solitary Fibrous Tumour Shows Up

Most solitary fibrous tumours grow slowly and cause few symptoms until they reach a noticeable size. What you feel depends almost entirely on where the tumour sits, because the main problem an SFT causes is pressure on whatever is next to it.

• A painless, slowly enlarging lump — in the arm, thigh, trunk or neck, often present for months or years before it is checked.
• Chest symptoms — a pleural SFT can cause breathlessness, cough or chest discomfort once it is large enough to compress the lung.
• Abdominal or pelvic fullness — a retroperitoneal or pelvic SFT may be found because of vague bloating, a palpable mass, or pressure on the bladder or bowel.
• Low blood sugar (Doege-Potter syndrome) — a rare but striking feature of very large SFTs, where the tumour releases an insulin-like substance causing episodes of hypoglycaemia.

Because the commonest presentation is simply a deep, painless lump, an SFT is easy to dismiss as harmless — which is exactly why any unexplained soft tissue mass deserves proper imaging and a specialist opinion rather than reassurance alone. Our guide to sarcoma treatment in Hyderabad explains how a suspicious lump is worked up from first scan to surgery.

How a Solitary Fibrous Tumour Is Diagnosed

SFT is one of the more confidently diagnosable soft tissue tumours, because it carries a single, defining molecular fingerprint. Putting the diagnosis beyond doubt takes a combination of imaging, a tissue sample, and one key stain.

Imaging — MRI, CT and a Vascular Clue

For a limb or pelvic mass, MRI is the imaging investigation of choice; for a chest mass, CT is used. SFTs are typically well-defined and highly vascular — they take up contrast strongly because of their rich blood supply. That vascularity is an important clue for the surgeon, because it means bleeding has to be planned for during removal. A chest CT is also used to check whether an SFT elsewhere in the body has spread to the lungs.

Biopsy and the STAT6 Stain

A core needle biopsy provides the tissue needed to confirm the diagnosis. Under the microscope, SFTs show a "patternless" arrangement of spindle cells with characteristic branching, "staghorn" blood vessels — the very feature that earned them the old name hemangiopericytoma. The decisive test, however, is the STAT6 immunostain: nuclear STAT6 positivity is the read-out of the underlying NAB2-STAT6 gene fusion and is present in almost all SFTs. A positive STAT6, together with markers such as CD34 and STAT6's molecular confirmation, separates SFT from look-alike sarcomas with very high reliability — which is why getting the biopsy reviewed by a sarcoma pathologist matters.

The Risk-Stratification Score — Benign vs Malignant SFT

The most practical question — "is my SFT benign or malignant?" — is not answered by a single yes or no. Instead, pathologists use a risk-stratification score that combines four features to estimate how likely the tumour is to recur or spread: the patient's age, the tumour size, the number of mitoses (dividing cells) per high-power field, and the presence or absence of tumour necrosis (dead tissue inside the tumour). The score sorts patients into low, intermediate, and high-risk groups, which then guides how aggressively the tumour is treated and how long it is watched. A large tumour with many mitoses and necrosis behaves like a sarcoma and is treated as malignant; a small, low-mitotic tumour in a younger patient usually behaves benignly.

Treatment of Solitary Fibrous Tumour

The cornerstone of treatment for a localised solitary fibrous tumour is complete surgical removal with a clear margin. Done well the first time, surgery offers the best — and often the only — chance of cure. The role of radiation and drug therapy depends on the risk score, the margin achieved, and whether the disease has spread.

Surgery — Complete (R0) Excision

The aim is to remove the whole tumour together with a cuff of normal tissue so that no cancer cells reach the cut edge of the specimen — a margin-negative, or R0, resection. Because SFTs are so vascular, the operation is planned to control bleeding, and the biopsy track is removed along with the tumour. For SFTs of the arm or leg this is the same operation as for other sarcomas: a planned, margin-clear removal. You can read how clear margins are achieved and why they matter in our detailed guide to wide local excision & clear margins explained.

Radiation

Radiation is not needed for every SFT. It is considered when the margin is close or positive and further surgery is not possible, for high-risk (malignant-behaving) tumours where it lowers the chance of local recurrence, or as a way to control symptoms from a tumour that cannot be fully removed — for example, a meningeal SFT inside the skull.

Systemic Therapy for Metastatic SFT

If an SFT has spread — most commonly to the lungs, bones or liver — surgery alone is no longer enough. Because these tumours are richly supplied by blood vessels, anti-angiogenic drugs that target the tumour's blood supply are an important treatment, and are chosen by the medical oncologist according to the pace and pattern of the disease. Conventional sarcoma chemotherapy may also be used in selected cases. A few isolated lung metastases can sometimes be removed surgically (metastasectomy) when the rest of the disease is controlled.

Outlook, Follow-Up and Cost in Hyderabad

For most patients with a low-risk, completely removed solitary fibrous tumour, the outlook is good and the chance of cure with surgery alone is high. The features that worsen the outlook are large size, a high mitotic count, tumour necrosis, and incomplete (positive-margin) surgery — the same factors that drive the risk score. Even so, because SFT can relapse very late, long-term follow-up imaging is standard for everyone, with the interval and duration matched to your risk group.

At CION, that follow-up is planned at the multidisciplinary tumour board so that a low-risk patient is not over-treated and a high-risk patient is not under-watched. If a recurrence or a lung metastasis is found, it is staged and discussed afresh — late relapse is treatable, and a single returning nodule is a very different situation from widespread disease.

Indicative Cost in Hyderabad

Costs are indicative. A personalised estimate is provided after your CION consultation. EMI options and cashless support through major TPAs, Aarogyasri, CGHS, ECHS & ESI are available for eligible patients.

Why Patients Choose CION for Solitary Fibrous Tumour Care

A rare tumour like SFT is best treated where the diagnosis is confirmed precisely, the surgery is planned, and the follow-up is long-term. Here is why patients trust CION.

Get a Clear Answer on Your SFT

A solitary fibrous tumour is rare enough that a confident diagnosis and a planned operation make all the difference. If you are holding an SFT or hemangiopericytoma report, talk to a specialist who treats these tumours regularly.