Angiomatoid Fibrous Histiocytoma, from the CureRays guide library.

Angiomatoid fibrous histiocytoma is a rare, slow-growing soft-tissue tumor of children and young adults that usually behaves gently; complete surgical removal cures most people, and only a small minority ever recur or spread.

What it is.

Angiomatoid fibrous histiocytoma (AFH) is a rare soft-tissue tumor that most often appears in children, teenagers, and young adults, typically as a slow-growing lump just under the skin of an arm, leg, or the trunk. Under the microscope it has a distinctive look — sheets of bland cells surrounding blood-filled spaces (the 'angiomatoid' part) wrapped in a fibrous shell, often with a cuff of immune cells — and it is defined by a characteristic gene rearrangement, most often EWSR1-CREB1 (and sometimes EWSR1-ATF1 or related fusions). Because it can cause systemic symptoms such as low-grade fever, anemia, or weight loss — thought to be driven by the tumor releasing a signaling protein called interleukin-6 — it is sometimes mistaken for an infection or other illness before it is correctly identified. AFH is classified as a tumor of low malignant potential: the great majority are cured by complete surgical removal, around one in seven may recur locally if not fully removed, and only a very small fraction (roughly 1–5%) ever spread to distant sites such as lymph nodes or the lungs. For the rare metastatic case, chemotherapy (such as doxorubicin) and targeted approaches like blocking the interleukin-6 pathway have been explored. The overall outlook is excellent.

How radiation treats it.

Radiation damages the DNA inside cancer cells so they can no longer divide and survive, while healthy cells are better at repairing themselves. Angiomatoid fibrous histiocytoma is treated chiefly with surgery, and most people never need radiation. When it is used, it is usually added after surgery for a tumor that could not be removed with a clean margin and cannot be re-operated, to lower the chance of local recurrence. In those situations radiation is delivered as short, painless daily sessions and leaves no radioactivity in your body, so you remain safe to be around family and children.

The ways we can treat it.

Surgery. Wide local excision removes the tumor with a cuff of normal tissue, the decisive and usually curative treatment; complete removal minimizes the chance it returns.

Radiation (selected). Not routinely needed, but radiation may be added after surgery for tumors with positive margins that cannot be re-excised, or for difficult locations, to improve local control.

Systemic therapy (rare). For metastatic disease, chemotherapy circulates through the body, and targeted drugs that block interleukin-6 signaling have been used in selected refractory cases.

Questions we hear often.

Is angiomatoid fibrous histiocytoma a dangerous cancer? It is considered a tumor of low malignant potential — much gentler than most sarcomas. The great majority are cured by complete surgical removal, only a minority recur locally, and distant spread is rare. The outlook is excellent.

Why did I have fevers and feel unwell before diagnosis? AFH can release a signaling protein called interleukin-6, which causes symptoms such as low-grade fever, anemia, or weight loss. These can mimic an infection, but they typically resolve once the tumor is removed.

Will I need chemotherapy or radiation? Most people need only surgery. Radiation is occasionally added if the tumor could not be removed with a clean margin. Chemotherapy and targeted drugs are reserved for the rare case that spreads to distant sites.

This guide is informational only. It is not medical advice — please confirm anything here with your care team.