A Closer Look At Extraskeletal Myxoid Chondrosarcoma Within The Lower Extremity

Exploring the diagnosis and treatment of a rare case of extraskeletal myxoid chondrosarcoma in a 67-year-old woman, these authors emphasize the importance of imaging, surgical resection and consultations with other specialties.

Extraskeletal myxoid chondrosarcoma is an extremely rare malignancy that possesess unique morphologic, histologic and immunohistochemical features. Extraskeletal myxoid chondrosarcoma comprises an estimated 2.5 percent of soft tissue sarcomas and is characterized in most cases by a chromosomal translocation resulting in the production of the EWSR1-CHN protein.¹ The fusion gene products are generally responsible for alterations in cellular growth and differentiation.

Extraskeletal myxoid chondrosarcoma is slow growing with 10-year survival rates ranging from 65 to 78 percent.¹ To date, wide local excision is the only viable treatment option that offers patients a potential cure. Radiation in doses of up to 70 Gy can reportedly achieve a substantial reduction in tumor size in individual patients but this modality has not been associated with better outcomes in larger comparative studies.¹ No prospective trials have examined the effectiveness of radiation therapy for the treatment of extraskeletal myxoid chondrosarcoma.

With this in mind, let us discuss key considerations in a case involving the management of extraskeletal myxoid chondrosarcoma within the lower extremity.

What You Should Know About The Patient Presentation And Diagnosis

A 67-year-old woman with no significant past medical history initially presented to the podiatric office with concerns of a painful bump on the top of her left foot. According to the patient, the soft tissue mass had been present for a few months and had been increasing in size. She reported occasional bouts of discomfort, especially when ambulating in shoes. Initial radiographs of the left foot revealed no gross bony abnormalities. Subsequently, magnetic resonance imaging (MRI) revealed a prominent lobulated soft tissue mass in relation to the first metatarsal and first interspace, extending as far distally as the first metatarsophalangeal joint region.

Due to the clinical and MRI findings, we took the patient to the operating room for excision of the soft tissue mass. The pathologist evaluated the specimen in the hospital where the procedure took place and then sent out the specimen for further evaluation to the Johns Hopkins pathology department. The pathology report revealed an extraskeletal myxoid chondrosarcoma, Fédération Nationale des Centres de Lutte Contre Le Cancer (FNCLCC) Grade I with positive margins. The mass measured 4.9 x 3.6 x 1.0 cm and weighed 11 g.

The patient then had a positron emission tomography/computed tomography (PET/CT) whole body attenuation scan. This revealed mildly increased soft tissue density over the left foot between the hallux and the second digit. We could not exclude residual postoperative changes or recurrent sarcoma.

Upon reviewing the reports, we referred the patient to an orthopedic oncologist. Due to the findings, the specialist took the patient back to the operating room for a second more definitive procedure. She had an open Lisfranc amputation along with the application of a bilayered bioengineered alternative tissue graft. The use of negative pressure therapy over the graft site assisted with the wound healing process.

To date, the patient requires neither further surgery nor chemotherapy. The orthopedic oncologist will conduct close follow-up. At the six-month follow-up period, the patient remained well healed from surgery and is currently cancer-free.

What The Literature Reveals About Extraskeletal Myxoid Chondrosarcoma

Currently there are very limited case studies and research published on extraskeletal myxoid chondrosarcoma in the literature, especially podiatric literature. The myxoid chondrosarcoma is a rare tumor and according to the literature, only 2 percent occur outside of the skeleton.¹

An accurate diagnostic and therapeutic algorithm allows a precise preparation for surgery.² Wide excision with negative margins appears to be the appropriate initial approach for those diagnosed with this malignancy. Even with adequate surgical margins, recurrence reportedly occurs in about 25 percent of patients.³

It is essential for foot and ankle surgeons to perform a thorough history and evaluation when a patient presents with any sort of soft tissue mass on the foot. Downgrading the importance of further imaging studies as well as a biopsy may result in serious implications. Although the reports revealed the patient’s tumor to be located within the first interspace, the decision to perform a Lisfranc amputation ensured that the resection was proximal enough.

Despite a few reports of chemotherapeutic response, to our knowledge, there are no successful chemotherapeutic agents that effectively fight against extraskeletal myxoid chondrosarcoma. The use of radiotherapy for extraskeletal myxoid chondrosarcoma is controversial. Some studies show that these tumors are resistant to radiotherapy and other studies maintain that this is a radioresponsive tumor and one should consider radiotherapy.³

In Conclusion

Extraskeletal myxoid chondrosarcoma is a rare form of sarcoma that requires immediate attention and aggressive therapy. With overall five- and 10-year survival rates of 87 percent and 63 percent respectively, it is necessary to intervene with a wide surgical resection. Without a surgical cure, patients may face poor outcomes in the future. As podiatric surgeons, It is important for us to obtain proper imaging, perform surgical resections of concerning lesions and consult oncology whenever necessary.

Dr. Masqati is a third-year resident with the Crozer-Keystone Health System Podiatric Residency Program in Chester, PA.

Dr. Cornell is a Diplomate of the American Board of Foot and Ankle Surgery. She is fellowship-trained in diabetic limb salvage and currently in private practice in Havertown, Pa. She is an attending physician with the Crozer-Keystone Health System Podiatric Residency Program.

References

1. Mitchell AP, Poiesz M, Leung A. A case of highly aggressive extraskeletal myxoid chondrosarcoma. Case Rep Oncol. 2011; 4(2):377–84. 
2. Mroczkowski P, Evert M, Tautenhahn J, et al. A rare extra-skeletal myxoid chondrosarcoma of the lower leg - is amputation absolutely necessary. Zentralbl Chir. 2010; 135(1):83–6. 
3. Sayal N, Lepoudre C, Pui J. Extraskeletal myxoid chondrosarcoma of the neck. Otolaryngol Case Rep. 2017; 2(3):22–5.