In the year 1972, Enzinger and Shiraki [1] defined the myxoid variant of extraskeletal chondrosarcoma, based on the multinodular growth of primitive chondroblast-like cells in an abundant myxoid matrix. The age at presentation of this neoplasm ranges from 4 to 92 years, and it mainly affects middle-aged patients. There is no sexual or racial predilection.

Histogenesis of EMC is controversial. In any case, chondroblast differentiation is a proven fact in several histochemical and ultrastructural studies.

In spite of the fact that, according to the reviewed literature, most cases appear on the lower limbs, location on the foot is very rare. In this article, we present the case of EMC of the foot and we review the cases published over the last years.

We present a case of a 39-year-old male who is admitted in our department after being referred from Primary Care, with pain on the plantar region of the right foot of several months of evolution. In the physical examination, the patient presents a hard immobile tumor of approximately 3–4 cm on the base of the fourth metatarsal bone. The rest of the physical examination is normal. An MRI is performed, and it reveals a solid lesion of 3.4×5.3×3 cm in size, with necrotic areas inside, located on the plantar region and infiltrating different musculotendinous and bone structures in the area (Figure 1).

Further bone scan, chest X-ray and blood tests are normal.

A Tru-Cut biopsy is performed on the safest and most accessible area (dorsum of the base of the fourth metatarsal bone). The histopathological report describes a chondral origin tissue, with low cellularity and atypia, surrounded by abundant myxoid matrix. The specimen was unencapsulated. After a review of literature and confirmation that there is no clear consensus on an optimum treatment, an amputation below-knee is performed because it is the most functional choice with non-affected borders. The patient was not undergone to chemotherapy.

The postoperative evolution was favorable. Five months after surgery the patient clinical state is good and there is no evidence of distance metastasis in the monthly controls that are performed.

Extraskeletal myxoid chondrosarcoma is a rare entity that can be located both on the upper and the lower limbs, and is more commonly found on the thigh and the knee [2]. The foot is an extremely rare location for this pathology, and it receives different treatments depending on reviewed literature [3].

The age at presentation ranges from 4 to 92 years, and it is most common in midlife. There is no sexual or racial predilection.

Usually, patients present a clinical history of pain on the affected region and the appearance of a growing mass of months of evolution. The tumor grows very slowly and it is sometimes a casual finding, which can delay diagnosis significantly [4] [5] .

Plain X-rays usually show a soft tissue mass that sometimes penetrates the underlying bone. The diagnostic study is completed with MRI and an adequate staging study that includes a bone scan and an analysis with tumor markers. Diagnostic certainty is obtained with the anatomopathological study of a sample obtained either via biopsy or complete removal of the tumor.

There is no consensus in reviewed literature with regard to the optimum treatment. Table 1 gives an analysis of the cases of EMC of the foot found in the literature. As we can see, in most of them (63%), including our case, the patients underwent amputation (amputation level is not specified in the studies). In view of the data, both the patients who underwent amputation and those in whom the tumor was resected with free margins are alive and disease-free in the follow-up control studies that were carried out (with the exception of one case in which the patient maintains the lung metastasis of the initial diagnosis [6] and another case in which the patient developed a metastasis in the chest wall 36 months after diagnosis and who is still alive 14 years after the initial treatment [7].

The reviewed literature shows a relatively good prognosis of the tumor, with prolonged survival. This characteristic is not only applicable to cases of the foot; most studies report a good prognosis regardless of the location. Saleh et al., in a study from 1992 on 10 patients with EMC of different locations (one of them of the foot) question this good prognosis. The authors present a series in which, in spite of a long survival, 100% of the patients developed distant metastasis or local recurrence (many of them more than 10 years later). The only case of their series in which the location of the tumor was on the foot presented with lung metastasis at diagnosis, and the patient received chemotherapy as a single treatment (without response). Fourteen years later, the patient is still alive and the lung metastases are still present [6].

Our analysis reveals that most of the patients show long-term survival, even in the presence of metastasis. The low number of cases with location on the foot makes it difficult to discern clear prognostic factors. Oliveira et al. [8] refer to prognostic factors such as the size of the tumor, cellularity, mitotic activity, or the presence of different immunohistochemical markers, regardless of the location.

Extraskeletal myxoid chondrosarcoma (EMC) of the foot is an extremely rare condition with a relatively good prognosis even in the presence of distant metastasis, and which in most cases shows good results with amputation, which should be as functional as possible, as a treatment of choice. Larger case series are required to establish clear criteria with regard to prognostic factors.

1. Enzinger FM, Shiraki M. Extraskeletal myxoid chondrosarcoma. An analysis of 34 cases. Hum Pathol 1972 Sep;3(3):421–35.   [Pubmed]    
2. Meis-Kindblom JM, Bergh P, Gunterberg B, Kindblom LG. Extraskeletal myxoid chondrosarcoma: A reappraisal of its morphologic spectrum and prognostic factors based on 117 cases. Am J Surg Pathol 1999 Jun;23(6):636–50.   [Pubmed]    
3. Amir D, Amir G, Mogle P, Pogrund H. Extraskeletal soft-tissue chondrosarcoma. Case report and review of the literature. Clin Orthop Relat Res 1985 Sep;(198):219–3.   [CrossRef]   [Pubmed]    
4. Ream JR, Corson JM, Holdsworth DE, Millender LH. Chondrosarcoma of the extraskeletal soft tissue of the finger. Clin Orthop Relat Res 1973 Nov-Dec;(97):148–52.   [CrossRef]   [Pubmed]    
5. Goldenberg RR, Cohen P, Steinlauf P. Chondrosarcoma of extraskeletal soft tissues. A report of seven cases and review of literature. J Bone Joint Surg Am 1967 Dec;49(8):1487–507.   [Pubmed]    
6. Saleh G, Evans HL, Ro JY, Ayala AG. Extraskeletal myxoid chondrosarcoma. A clinicopathologic study of ten patients with long-term follow-up. Cancer 1992 Dec 15;70(12):2827–30.   [CrossRef]   [Pubmed]    
7. Kawaguchi S, Wada T, Nagoya S, et al. Extraskeletal myxoid chondrosarcoma: a Multi-Institutional Study of 42 Cases in Japan. Cancer 2003 Mar 1;97(5):1285–92.   [CrossRef]   [Pubmed]    
8. Oliveira AM, Sebo TJ, McGrory JE, Gaffey TA, Rock MG, Nascimento AG. Extraskeletal myxoid chondrosarcoma: A clinicopathologic, immunohistochemical, and ploidy analysis of 23cases. Mod Pathol 2000 Aug;13(8):900–8.   [CrossRef]   [Pubmed]