Case 5 -
Cardiac Sarcoma, Pleomorphic Undifferentiated Type, Arising on Mitral Valve
Allen P. Burke
University of Maryland Medical System
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A 24-year old man presented with shortness of breath. Imaging demonstrated multiple masses in the
lungs, which were believed to represent septic emboli. Echocardiography demonstrated a vegetation of
the anterior mitral valve leaflet, which was excised, and measured 2.5 x 1.2 x 1.1 cm. Further
evaluation demonstrated multiple masses the liver, which demonstrated high-grade sarcoma on biopsy.
Case 5 - Slide 1
The lesion was fragmented, bulbous to bosselated tissue, the largest 2.5 cm in diameter, as well as
portions of mitral valve leaflet.
Cardiac sarcoma, pleomorphic undifferentiated type, arising on mitral valve
Tumors of heart valves are rare. The most common is papillary fibroelastoma, which is not a neoplasm,
but probably a reactive proliferation. Histologically, papillary fibroelastoma has no features in common
with sarcomas, as an avascular, paucicellular papillary structure lined by a single lining of endothelial
cells. Papillary fibroelastomas occasionally occur in areas of previous endocardial damage or in
patients with preexisting heart disease . Most symptoms arise from left-sided lesions that shower
fibrin clots into the cerebral circulation or prolapse into the coronary orifice. The most common
symptoms are transient neurological defects and myocardial ischemia, and rarely sudden death. These
lesions are considered a form of Lambl's excrescence, but unlike Lambl's excrescences, papillary
fibroelastomas can become quite large, and occur on any valve surface or area of the endocardium .
Thrombi may occur on the surface of the proliferation, and dislodged clots are responsible for embolic
symptoms. Histologically, they are avascular papillary structures lined by endothelial cells. They are
often mistaken for cardiac myxoma, which are vascular and of heterogeneous cell types. Papillary
fibroelastoma is cured by surgery, whether there are pre-existing embolic symptoms, or if a lesion is
incidentally discovered. Asymptomatic patients could be treated surgically if the tumor is mobile, as
the tumor mobility is the independent predictor of death or nonfatal embolization. Asymptomatic patients
with nonmobile lesions can be followed-up closely with periodic clinical evaluation and echocardiography,
and receive surgical intervention when symptoms develop or the tumor becomes mobile. Recurrences are
rare, and valve-sparing surgery should be considered whenever possible, as regrowth of partially
resection lesions does not always occur.
Cardiac inflammatory myofibroblastic tumors are probably the second most common heart valve tumor,
although distinctly uncommon. Inflammatory myofibroblastic tumors (IMFTs) are proliferations of
uncertain histogenesis, which vary in appearance from inflammatory, reactive-appearing proliferations to
low-grade sarcomas. These lesions occur in children and young adults, with a mean age at presentation
younger than cardiac sarcoma (10 years, as compared to 40-50 years for sarcomas).
 There is probably
organ-specific variation in the histologic characteristics of IMFT. In the heart, they invariably arise
from the endocardium, including valve leaflets, may have areas that are cellular, and usually have
abundant myxoid matrix and surface fibrin. There is generally a background lymphocytic infiltrate.
However, embolic symptoms and sudden death from coronary occlusion may occur. Several pediatric heart
tumors, reported in the medical literature as sarcomas, are likely IMFT, given good prognosis, location
on valves, and available histologic descriptions. The current designation for these lesions is still
debated, the term low-grade myofibroblastic sarcoma sometimes favored. 
Cardiac sarcomas fall into two general groups: angiosarcomas, and a more heterogeneous group of
sarcomas that appear to derive from the intimal and form luminal masses. Angiosarcomas are typically
right-sided, and are infiltrative lesions that may involve the tricuspid valve, but do not arise from the
endocardial surface . In contrast, so-called "intimal" sarcomas arise from and spread long the left
atrial endocardium, and often have a large intraluminal growth mass before significantly infiltrating the
atrial wall.  Histologically, these lesions are pleomorphic, and typically show undifferentiated
areas similar to MFH, as well as blander areas with fibroblastic spindle cell growth. Spread along the
intimal surface with "in situ" growth is occasionally identified. Other forms of differentiation may
occur, including osteo- chondro- and synovial sarcoma; the latter are usually monophasic and possess
When primary intimal sarcomas of the heart involve the valves, it is typically the mitral valve, as
the left atrium is the most common site. Although the valve may be secondarily involved by an
enlargement mass arising on the atrial endocardium, origin on the valve surface is distinctly rare
The second most common valve involved by sarcoma is the pulmonary valve, and these lesions
overlap with primary sarcomas of the pulmonary intima.
Intimal sarcomas in the pulmonary artery
are more likely to demonstrating heterologous elements and matrix formation than their left atrial
The current case shows difficulty in separating cardiac sarcomas from IMFTs, as they both arise from
intima; the distinction is especially difficult when the valve is the site of origin. Tin contrast to
intimal sarcoma, hose cardiac sarcomas reported on heart valves in children are likely either benign IMFT
or low-grade lesions, in contrast to intimal sarcomas, as this case, which have a dismal prognosis
Histologic features that distinguish the two lesions are several: those that are
characteristic of sarcomas include mitotic activity, severe atypia especially on the surface, and
(somewhat counter intuitively) areas of bland monomorphous growth with dense collagen. Features of IMFT
are the presence of larger myofibroblastic cells with open nuclei ("tissue culture" appearance),
inflammation, and lack of monomorphous spindle cell areas. Features common to both include surface
fibrin, areas of dense collagen, and a polypoid growth pattern.
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