Pleomorphic undifferentiated sarcoma

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Pleomorphic undifferentiated sarcoma
Pleomorphic undifferentiated sarcoma - very high mag.jpg
Micrograph of a pleomorphic undifferentiated sarcoma. H&E stain.
Classification and external resources
Specialty Oncology
ICD-10 C49 (ILDS C49.M10)
DiseasesDB 31471
eMedicine radio/420
MeSH D051677

Pleomorphic undifferentiated sarcoma (abbreviated PUS), also undifferentiated pleomorphic sarcoma and previously malignant fibrous histiocytoma (abbreviated MFH), is a type of soft tissue sarcoma.

It is considered a diagnosis of exclusion for sarcomas that cannot be more precisely categorized.[1][2]


PUS is regarded as the most common soft tissue sarcoma of late adult life. It rarely occurs in children.[3] It occurs more often in Caucasians than in those of African or Asian descent and is a male-predominant disease, afflicting two males for every female.


PUS occurs most commonly in the extremities and retroperitoneum, but has been reported in other sites. Metastasis occurs most frequently in the lungs (90%), bones (8%), and liver (1%).

In the extremities, it presents itself as a painless enlarging soft tissue mass.


It can be detected by magnetic resonance imaging (MRI), but a biopsy is required for the definitive diagnosis. MRI findings typically show a well-circumscribed mass that is dark on T1-weighted images and bright on T2-weighted images. Central necrosis is often present and identifiable by imaging, especially in larger masses.


Pleomorphic undifferentiated sarcomas are, by definition, undifferentiated, meaning (as the name implies) that they do not bear a resemblance to any normal tissue.

The histomorphology, otherwise, is characterized by high cellularity, marked nuclear pleomorphism, usually accompanied by abundant mitotic activity (including atypical mitoses), and a spindle cell morphology. Necrosis is common and characteristic of high grade lesions.


Treatment consists of surgical excision (the extent of which ranges from tumor excision to limb amputation, depending on the tumor) and in some cases radiation. Chemotherapy remains controversial in MFH. The usual site of metastatic disease is the lungs, and metastases should be resected if possible.


Prognosis depends on the primary tumor grade (appearance under the microscope as judged by a pathologist), size, resectability (whether it can be completely removed surgically), and presence of metastases. The five-year survival ranges from 35 to 60%.

Human-human transmission[edit]

There is a case report of human-human transmission, in a surgeon who injured his hand while working on a PUS case.[4]


  1. ^ Matushansky I, Charytonowicz E, Mills J, Siddiqi S, Hricik T, Cordon-Cardo C (August 2009). "MFH classification: differentiating undifferentiated pleomorphic sarcoma in the 21st Century". Expert Rev Anticancer Ther 9 (8): 1135–44. doi:10.1586/era.09.76. PMC 3000413. PMID 19671033. 
  2. ^ "Neoplasia". 
  3. ^ Alaggio R, Collini P, Randall RL, Barnette P, Million L, Coffin CM (2010). "Undifferentiated high-grade pleomorphic sarcomas in children: a clinicopathologic study of 10 cases and review of literature". Pediatr. Dev. Pathol. 13 (3): 209–17. doi:10.2350/09-07-0673-OA.1. PMID 20055602. 
  4. ^ Gärtner, Hermine-Valeria; Christian Seidl; Christine Luckenbach; Georg Schumm; Erhard Seifried; Horst Ritter; Burkhard Bultmann (1996-11-14). "Genetic Analysis of a Sarcoma Accidentally Transplanted from a Patient to a Surgeon". N Engl J Med 335 (20): 1494–1497. doi:10.1056/NEJM199611143352004. PMID 8890100. Retrieved 2010-01-05. 

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