Overview
Pleomorphic undifferentiated sarcoma, formerly known as malignant fibrous histiocytoma (MFH), is a type of soft tissue cancer (sarcoma) that develops most often in adults. The term 'OBSOLETE' in the disease name reflects that this diagnosis has been reclassified in modern medical practice. What was once called malignant fibrous histiocytoma is now more accurately categorized under other sarcoma subtypes using updated pathology techniques. However, the term pleomorphic undifferentiated sarcoma is still used when a soft tissue tumor cannot be classified into a more specific sarcoma type after thorough testing. This cancer most commonly appears in the arms, legs, or the area behind the abdominal organs (called the retroperitoneum). It typically presents as a painless or sometimes painful lump that grows over weeks to months. The tumor is made up of abnormal cells that look very different from one another under the microscope, which is what 'pleomorphic' means. Treatment usually involves surgery to remove the tumor, often combined with radiation therapy. Chemotherapy may be used in cases where the cancer has spread or cannot be fully removed surgically. The outlook depends on the tumor's size, location, depth, and whether it has spread to other parts of the body. Because this is an aggressive cancer, early detection and treatment by a specialized sarcoma team are very important for the best possible outcomes.
Key symptoms:
A painless or painful lump under the skin or deep in the bodySwelling in an arm or legA mass that grows over weeks to monthsPain or discomfort near the tumorLimited movement if the tumor is near a jointAbdominal fullness or bloating if the tumor is in the belly areaUnexplained weight lossFatigueNumbness or tingling if the tumor presses on nervesDifficulty breathing if the cancer spreads to the lungs
Sporadic
Usually appears on its own, not inherited from a parent
Adult
Begins in adulthood (age 18 or older)
FDA & Trial Timeline
7 eventsYonsei University — NA
M.D. Anderson Cancer Center — PHASE2
Washington University School of Medicine — PHASE1
Medical University of South Carolina — NA
Centre Leon Berard — NA
University Hospital Heidelberg — NA
Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.
Treatments
No FDA-approved treatments are currently listed for OBSOLETE: Pleomorphic undifferentiated sarcoma.
6 clinical trialsare actively recruiting — trials can provide access to cutting-edge therapies.
View clinical trials →Specialists
View all specialists →No specialists are currently listed for OBSOLETE: Pleomorphic undifferentiated sarcoma.
Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Travel Grants
No travel grants are currently matched to OBSOLETE: Pleomorphic undifferentiated sarcoma.
Community
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Caregiver Resources
NORD Caregiver Resources
Support, advocacy, and financial assistance for caregivers of rare disease patients.
Mental Health Support
Rare disease caregiving can be isolating. Connect with counseling and peer support.
Family & Caregiver Grants
Financial assistance programs specifically for caregivers of rare disease patients.
Social Security Disability
Learn how rare disease patients may qualify for SSDI/SSI benefits.
Questions for your doctor
Bring these to your next appointment
- Q1.What is the exact size, grade, and stage of my sarcoma?,Can the tumor be completely removed with surgery, and will I need radiation or chemotherapy?,Should I seek a second opinion at a specialized sarcoma center?,Are there any clinical trials available for my type and stage of cancer?,What is my risk of the cancer coming back after treatment?,How will treatment affect my daily activities and ability to work?,What follow-up schedule and imaging will I need after treatment is completed?
Common questions about OBSOLETE: Pleomorphic undifferentiated sarcoma
What is OBSOLETE: Pleomorphic undifferentiated sarcoma?
Pleomorphic undifferentiated sarcoma, formerly known as malignant fibrous histiocytoma (MFH), is a type of soft tissue cancer (sarcoma) that develops most often in adults. The term 'OBSOLETE' in the disease name reflects that this diagnosis has been reclassified in modern medical practice. What was once called malignant fibrous histiocytoma is now more accurately categorized under other sarcoma subtypes using updated pathology techniques. However, the term pleomorphic undifferentiated sarcoma is still used when a soft tissue tumor cannot be classified into a more specific sarcoma type after th
How is OBSOLETE: Pleomorphic undifferentiated sarcoma inherited?
OBSOLETE: Pleomorphic undifferentiated sarcoma follows a sporadic inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does OBSOLETE: Pleomorphic undifferentiated sarcoma typically begin?
Typical onset of OBSOLETE: Pleomorphic undifferentiated sarcoma is adult. Age of onset can vary across affected individuals.
Are there clinical trials for OBSOLETE: Pleomorphic undifferentiated sarcoma?
Yes — 6 recruiting clinical trials are currently listed for OBSOLETE: Pleomorphic undifferentiated sarcoma on UniteRare. See the clinical trials section on this page for phase, sponsor, and site details sourced from ClinicalTrials.gov.