In short
- You should have two documents: the histopathology report and a molecular (FISH or NGS) report — ask for copies of both.
- Intimal sarcoma is defined by gene amplification, above all MDM2 (about two thirds of cases), often with CDK4 and PDGFRA.
- R0 on the surgery report means complete removal — the strongest predictor of long survival.
- The molecular profile decides which targeted drugs and trials are even possible.
- Tissue in the pathology archive can usually still be tested later — it is never too late to ask.
The two documents you will receive
After a biopsy or surgery you will get a histopathology report — what the pathologist saw under the microscope — and, if the tissue was tested further, a molecular report from FISH (a test that counts gene copies with fluorescent probes) or next-generation sequencing (NGS, which reads hundreds of genes at once). Ask for copies of both. They are yours, they are the basis of every treatment decision, and they are what any second opinion, trial or research comparison will need.
If you were never given a molecular report, that is worth a question in itself: was the tumour tested for MDM2, and was a sequencing panel run? If not, tissue kept in the pathology archive can usually still be tested, sometimes years later.
Words on the histopathology report
| Term | What it means |
|---|---|
| Intimal sarcoma | The diagnosis: a malignant tumour arising from the inner lining of a large vessel or the heart, recognised as a distinct entity in the WHO classification.4 You may also see "pulmonary artery sarcoma" or "undifferentiated sarcoma of the pulmonary artery". |
| High-grade | The cells look very abnormal and divide fast. Nearly all intimal sarcomas are high-grade; this is expected, not an extra bad sign. |
| Spindle cell / pleomorphic / epithelioid | Descriptions of cell shape. They help the pathologist; they do not change treatment. |
| Mitoses, necrosis, Ki-67 | Measures of how fast the tumour grows and whether parts of it have died. Used for grading. |
| Immunohistochemistry: MDM2 positive, CDK4 positive | Stains showing that the tumour cells make a lot of MDM2 and CDK4 protein — the usual first hint of the gene amplification that defines the disease. Other stains (SMA, desmin, CD31, ERG, S100, keratins…) are used to rule out other tumours. |
| Margins: R0 / R1 / R2 | Only on a surgical specimen. R0 = no tumour at the cut edge (complete removal); R1 = tumour cells at the edge under the microscope; R2 = visible tumour left behind. R0 is the strongest known predictor of long survival, so this line matters a great deal. |
| Tumour size, extent, lymph nodes | How large the tumour was and which structures it reached. Lymph node spread is uncommon in sarcomas. |
Words on the molecular report
| Term | What it means |
|---|---|
| Amplification / copy number gain | The cell has extra copies of a gene. Normal cells have two. A report might say "MDM2 amplified, 14 copies". Amplification — rather than point mutations — is what drives intimal sarcoma.15 |
| MDM2 (12q15) | The defining alteration. Amplified in roughly 65–71% of intimal sarcomas.12 MDM2 switches off p53, the cell's main "brake"; too much of it lets the cell keep dividing. "12q15" is the address on chromosome 12. |
| CDK4 (12q14.1) | Sits next to MDM2 on chromosome 12 and is often amplified with it (reported in 43–81% of cases).1 CDK4 drives the cell cycle; it is the target of CDK4/6 inhibitor drugs. A 2025 study found CDK4 gains or loss of its counter-weight CDKN2A in 81% of 31 tumours.3 |
| PDGFRA (4q12) | A growth-factor receptor gene on chromosome 4, amplified in roughly 60–80% of cases depending on the series and method.12 It is the rationale for trying PDGFR-directed drugs, so far with limited success.6 |
| MDM4, CDK6 | Alternatives: a minority of intimal sarcomas amplify MDM4 or CDK6 instead of MDM2 or CDK4 — they are mutually exclusive.1 If your report shows MDM4 rather than MDM2, the diagnosis still fits. |
| EGFR, TERT, KIT, others | Other genes reported as amplified in some series (EGFR in up to 76% in one older FISH study).2 Their significance is unclear. |
| CDKN2A loss / deletion | Loss of a gene that normally restrains CDK4 — another way to push the cell cycle. Seen in a subset.3 |
| TMB (tumour mutational burden) | Number of mutations per million DNA letters. Intimal sarcomas are usually low (a few per megabase), which generally predicts a weaker response to immunotherapy. |
| MSI / MSS | Microsatellite instability. Nearly always "stable" (MSS) in this disease. |
| PD-L1 | A protein that tumours use to hide from immune cells; measured as a percentage of cells. Positive in a subset of intimal sarcomas.3 |
| Tumour content / purity | The share of tumour cells in the tested sample. Low content (below ~20%) can make results unreliable, especially "negative" ones. |
| VUS (variant of uncertain significance) | A DNA change whose meaning is unknown. Usually not actionable. |
What a typical profile looks like — and what ours looked like
The published series agree on the broad picture: amplification of MDM2, CDK4 and PDGFRA, few point mutations, low mutational burden, microsatellite stable.1235 Beyond that, almost every case has something individual.
To make this concrete, we published our own: Case IS-001, a completely resected pulmonary artery intimal sarcoma sequenced with a 517-gene panel.7 It showed the expected MDM2 (14 copies) and CDK4 (13 copies) amplification — but no PDGFRA amplification, and a very high amplification of a gene called YAP1 (28 copies) that does not appear as recurrent in any published intimal sarcoma series. One case proves nothing; it does show how much a single full report can add to a literature of roughly 120 sequenced cases. All of those published cases are summarised in our literature table.
Why the report matters for what happens next
- It confirms the diagnosis. MDM2 amplification in a tumour inside a large vessel is what separates intimal sarcoma from the things it can be confused with. If your report has no MDM2 result, ask for one.
- It is the basis for targeted treatment. MDM2 inhibitors, CDK4/6 inhibitors and PDGFR inhibitors only make sense if the corresponding gene is altered in your tumour — see targeted drugs.
- It decides trial eligibility. Most trials you could realistically join are defined by a molecular alteration ("MDM2-amplified solid tumours"), not by the diagnosis.
- It lets you compare. Put next to other cases, your profile helps answer the question nobody can answer today: which patterns behave how.
If you do not have a molecular report: what to ask for
- MDM2 testing (immunohistochemistry and/or FISH) on the tumour tissue, if not already done.
- A comprehensive NGS panel (several hundred genes, including copy-number analysis) — at a sarcoma center, through a precision-oncology programme, or via a commercial provider. Ask that the report include copy numbers, TMB and MSI.
- PD-L1 staining, in case immunotherapy is discussed.
- That tissue is preserved — paraffin blocks routinely, and if surgery is still ahead, ask whether a piece can be frozen or donated to research (see questions to ask).
- Copies of everything, as PDFs, for yourself.
In most European countries and in the US, molecular testing of a confirmed sarcoma is covered by insurance or the health system when requested by the treating center; ask your oncologist.
Send us your numbers
If you have a molecular report, the values on it — which genes, how many copies, TMB, MSI — are the single most useful thing you can share with this initiative. No names, no medical records: just the numbers. We will add them to the comparison and send you back what your profile looks like against every other case we hold. Send your profile →
Frequently asked
What does "MDM2 amplified" mean?
The tumour cells have many extra copies of the MDM2 gene instead of the normal two. MDM2 protein switches off p53, the cell's main growth brake, so too much of it lets the cell keep dividing. MDM2 amplification is the defining feature of intimal sarcoma, and the reason MDM2-inhibitor drugs are being tested.
Does a higher copy number mean a worse prognosis?
Nobody knows. There are far too few cases with both copy-number data and long-term outcome data to answer it — which is precisely the kind of question a linked case base could resolve.
Should I have my tumour sequenced?
For a rare, aggressive sarcoma most specialists would say yes: it confirms the diagnosis, identifies targetable alterations, and determines eligibility for molecularly defined trials. Ask your sarcoma center to arrange a comprehensive panel with copy-number analysis, and keep a copy of the report.
Sources
- Koelsche C, et al.. Intimal sarcomas and undifferentiated cardiac sarcomas carry mutually exclusive MDM2, MDM4, and CDK6 amplifications and share a common DNA methylation signature. Modern Pathology 2021. doi:10.1038/s41379-021-00874-y.
- Sarcoma Foundation of America. Intimal sarcoma (subtype information). curesarcoma.org accessed 2026. https://curesarcoma.org/sarcoma-subtypes/intimal-sarcoma/.
- Multi-omics study. Multi-omics analysis revealed potential use of immunotherapy and CDK4/6 inhibitors in intimal sarcoma (31 intimal sarcomas, 35 angiosarcomas). Frontiers in Immunology 2025. doi:10.3389/fimmu.2025.1668537.
- WHO Classification of Tumours Editorial Board. Soft Tissue and Bone Tumours, 5th edition (WHO Classification of Tumours series, vol. 3) — chapter on intimal sarcoma. IARC, Lyon 2020. https://publications.iarc.who.int/588.
- Review. Intimal sarcoma, review and future perspectives. Current Opinion in Oncology 2026. doi:10.1097/CCO.0000000000001246.
- Frezza AM, Assi T, Lo Vullo S, et al.. Systemic treatments in MDM2 positive intimal sarcoma: a multicentre experience with anthracycline, gemcitabine, and pazopanib within the World Sarcoma Network. Cancer 2020;126:98–104. doi:10.1002/cncr.32508.
- Intimal Sarcoma Initiative. Case IS-001 — full molecular profile and clinical course. intimasarc.com/case/; published molecular literature in one table: intimasarc.com/literature/.