| Topic | Key details | Best supporting source (first author year) | Publication date | URL/DOI |
|---|---|---|---|---|
| Definition/classification | IMT is a rare mesenchymal neoplasm of **intermediate malignancy** composed of myofibroblastic spindle cells with inflammatory infiltrates. Review states it is a “**rare neoplasm with intermediate malignancy characterized by a propensity for recurrence but a low metastatic rate**”; WHO-based framing in recent reviews describes it as a low-grade/borderline mesenchymal tumor and recommends AJCC 8th pTNM staging by site (pqac-00000011, pqac-00000007). | Chmiel 2024 | 2024-06-20 | https://doi.org/10.32604/or.2024.050350 |
| Epidemiology | IMT is extremely rare: **150–200 cases/year in the USA** were cited in a 2023 review, and overall prevalence was summarized as **0.04–0.7%**. Age distribution skews young: most patients are diagnosed **below 40 years**, with a **slight female predominance** in one 2024 review, while another notes predilection for children and young adults (pqac-00000008, pqac-00000011, pqac-00000002). | Wang 2023 | 2023-11-08 | https://doi.org/10.1007/s11864-023-01144-6 |
| Anatomic sites | The **lung** is the most common site in multiple reviews; other common locations are **abdomen/pelvis/retroperitoneum**, visceral organs, deep soft tissue, and head/neck. Recent review: “**The most common IMT manifestation is the lung**,” but tumors may arise in almost any site including bone, CNS, pericardium, heart, spinal meninges, uterus, and adrenal gland (pqac-00000011, pqac-00000008). | Chmiel 2024 | 2024-06-20 | https://doi.org/10.32604/or.2024.050350 |
| Recurrence/metastasis | Recurrence is a defining clinical risk: recent reviews report **~25% recurrence** overall. Metastasis is uncommon, typically **<5%**, with Fu et al. reporting **5/92 patients (5.4%)** metastatic. One review notes aggressive/atypical cases can reach **10.2% metastatic risk**, and lung IMT has especially low recurrence (**~2%**). Pediatric recurrence cited at **21%** in one review (pqac-00000008, pqac-00000010, pqac-00000011). | Chmiel 2024 / Wang 2023 | 2024-06-20 / 2023-11-08 | https://doi.org/10.32604/or.2024.050350 ; https://doi.org/10.1007/s11864-023-01144-6 |
| Key molecular alterations | ALK rearrangement is the major driver. Recent reviews summarize **~50%**, **~66.7%**, and **~70%** ALK-positive rates depending on cohort/series; one review states IMT is “**identified by the fusion of the anaplastic lymphoma kinase (ALK) gene, which is present in approximately 70% of cases**.” Known ALK partners include **RANBP2, IGFBP5, TPM4, SQSTM1**. Non-ALK kinase fusions occur, especially in ALK-negative IMT: **ROS1 (~5–10%)**, **NTRK3 (~5%)**, **RET**, **PDGFRB**. A 2023 case added **TPD52L2-ROS1** and notes ROS1 fusions in “**about 10% of IMT**” (pqac-00000011, pqac-00000009, pqac-00000014). | Chmiel 2024 / Liu 2023 | 2024-06-20 / 2023-09-14 | https://doi.org/10.32604/or.2024.050350 ; https://doi.org/10.1186/s13000-023-01382-0 |
| Diagnostics | Diagnosis relies on pathology plus molecular testing. Histology: spindle myofibroblastic/fibroblastic cells in myxoid-to-collagenous stroma with lymphoplasmacytic infiltrates; three patterns are described (myxoid/vascular, compact spindle, hypocellular fibrous). IHC often shows **ALK** (when rearranged) and **SMA** positivity; negative markers may include **S100, myogenin, CD117, EMA**. 2023 review states “**pathological and immunohistochemical tests are considered the gold standard**,” but **NGS** is emphasized because **FISH can be false-negative** and NGS identifies exact fusion partners. Imaging (CT/MRI) is helpful but nonspecific (pqac-00000009, pqac-00000010, pqac-00000014, pqac-00000015). | Wang 2023 | 2023-11-08 | https://doi.org/10.1007/s11864-023-01144-6 |
| Treatments/outcomes | **Surgery** is standard for localized disease and best prognosis when margins are negative. For advanced ALK+ disease, **crizotinib** became FDA-approved in **2020**; later approvals/usage include ceritinib, alectinib, brigatinib, lorlatinib. In adult single-center data, **16** advanced ALK+ patients treated with crizotinib had **ORR 81.3%**, **DCR 87.5%**, **median PFS 20.8 months**, and overall **5-year OS 77%** at median 30-month follow-up. Trial summary table reported crizotinib ORR **66.7% in ALK-positive** versus **14.3% in ALK-negative** disease, with mPFS **18.0 vs 14.3 months**; pediatric ceritinib trial ORR **70%** and DCR **80%**. Chemotherapy retrospective ORRs were **47.6%** (anthracycline-based) and **53.8%** (methotrexate-based). Recent review quotes: “**Targeted therapies are crucial for achieving sustained response**,” while noting resistance is common (pqac-00000013, pqac-00000011, pqac-00000008, pqac-00000007). | Liu 2023 / Chmiel 2024 | 2023-07 / 2024-06-20 | https://doi.org/10.4143/crt.2022.894 ; https://doi.org/10.32604/or.2024.050350 |
| Resistance/precision oncology | Resistance mechanisms are increasingly defined. A 2023 molecular tumor board case found **EML4-ALK** in primary and recurrent tumor, with secondary **ALK I1171N** mutation and persistent **EGFR activation (pEGFRY1068)** in recurrence. Quote: “**EGFR signaling in the background of a secondary ALK mutation is correlated with reduced ALK TKI sensitivity in vitro**,” supporting repeat biopsy plus multi-omics for therapy selection after relapse (pqac-00000012). | Hunt 2023 | 2023-05-31 | https://doi.org/10.1093/oncolo/oyad129 |
| Uterine IMT subset | In uterine IMT, abnormal uterine bleeding was the leading symptom (**51.85%, 14/27**), ALK IHC positivity was **96.3%**, and after median **8 months** follow-up all patients were alive and disease-free. The study emphasizes histology + IHC + **FISH/NGS** and notes fertility-sparing resection may be considered in selected patients (pqac-00000015, pqac-00000006). | Bai 2024 | 2024-09-20 | https://doi.org/10.3389/fonc.2024.1461092 |


*Table: This table compiles high-yield clinical, pathologic, molecular, diagnostic, and treatment facts for inflammatory myofibroblastic tumor using only the provided evidence contexts. It highlights recent statistics and actionable findings useful for a disease knowledge base or research report.*