Summary
Description
Benign cellular myxoma, or cellular myxoma of soft tissue, is a benign myxoid lesion that is histologically partway between intramuscular myxoma and low-grade myxofibrosarcoma. This lesion may also be called intramuscular myxoma.
People and Age
Adults, with a wide age range - 25 to 83
Symptoms and Presentation
A mass in the extremities
Brief description of the xray
No abnormality on xray
Brief desc of tx
Marginal excision is curative.
Tumor Name
Tumor Type
Benign or Malignant
Body region
Most Common Bones
Tumor behavior
Tumor density
Complete Information on this Tumor
Introduction and Definition
This solitary benign lesion occurs in the large muscles of the extremities in adults. It is usually found in the thigh, shoulder, upper arm, hip and buttocks.
Incidence and Demographics
Adults 25 to 85. Slighly more likely in females. Mean age around 50.
Symptoms and Presentation
A palpable mass with local pain, or a slowly growing painless mass.
X-Ray Appearance and Advanced Imaging Findings
No xray findings.
MRI Findings
The lesion is well defined, 2-15 cm (average around 5-6cm) with a mildly heterogeneous signal intensity on T! images, with higher signal intensity than fat and bone and lower than muscle. On T2 images the lesion has high to very high signal intensity with some internal complexity.
Laboratory Findings
None
Differential Diagnosis
Soft tissue sarcoma, low-grade myxofibrosarcoma, low-grade fibromyxoid sarcoma, and myxoid liposarcoma, myxoid neurofibroma, myxoid malignant peripheral nerve sheath tumor.
Histopathology findings
Grossly tan to tan-yellow. The cut surface has a wet, gelatinous, lobulated appearance.
Micro: See the five pathology images shown.
1st picture: Low power showing infiltration of skeletal muscle at the right side by a neoplasm with an extensive myxoid matrix and variable cellularity.
2nd picture: High power showing same as above. The lesions typically are grossly circumscribed but microscopically infiltrative.
3rd: Myxoid tumor with cytologically bland small stellate and spindle cells. There is no atypia, mitoses or necrosis. Small vessels may be seen but are not numerous.
4th: Higher power showing same as 3rd
5th: Less cellular or acellular areas of myxoid matrix may be present and have a microcystic appearance. This appearance by itself would be typical of an intramuscular myxoma; however, finding more the above more cellular myxoid matrix in at least 20% of the tumor makes this a cellular myxoma.
Micro: See the five pathology images shown.
1st picture: Low power showing infiltration of skeletal muscle at the right side by a neoplasm with an extensive myxoid matrix and variable cellularity.
2nd picture: High power showing same as above. The lesions typically are grossly circumscribed but microscopically infiltrative.
3rd: Myxoid tumor with cytologically bland small stellate and spindle cells. There is no atypia, mitoses or necrosis. Small vessels may be seen but are not numerous.
4th: Higher power showing same as 3rd
5th: Less cellular or acellular areas of myxoid matrix may be present and have a microcystic appearance. This appearance by itself would be typical of an intramuscular myxoma; however, finding more the above more cellular myxoid matrix in at least 20% of the tumor makes this a cellular myxoma.
Treatment Options for this Tumor
Marginal excision is curative - a more aggressive excision is not needed.
Preferred Margin for this Tumor
Marginal
Outcomes of Treatment and Prognosis
Excellent prognosis, with low rate of recurrence.
Suggested Reading and Reference
Histopathology. 2001 Sep;39(3):287-97.
Cellular myxoma of soft tissue: a clinicopathological study of 38 cases confirming indolent clinical behaviour.
van Roggen JF, McMenamin ME, Fletcher CD.
Cellular myxoma of soft tissue: a clinicopathological study of 38 cases confirming indolent clinical behaviour.
van Roggen JF, McMenamin ME, Fletcher CD.
