PMC3350304_01
Preoperative view showing an enlarging mass in the third web space.
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fig1
On examination, there was a firm, round mass measuring 9 x 7 cm in the third web space (Figure 1).
Preoperative positron emission tomography. (a) Abnormal uptake involving the affected foot. (b) No abnormal uptake was observed except left inguinal region.
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Radiological examination including fluorodeoxyglucose positron emission tomography showed no evidence of definite distant metastases except left inguinal region (Figures 2(a) and 2(b)).
Intraoperative views of ablative surgery and secondary reconstructive surgery. (a) Ipsilateral inguinal dissection at the first operation. (b) Wide excision of the primary lesion with a 30 mm surgical margin. (c) Free latissimus dorsi musculocutaneous flap transfer to the amputated stump.
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fig3
Left inguinal dissection was carried out (Figure 3(a)), and an adequately wide excision of the primary tumor with a 30 mm surgical margin (i.e., transmetatarsal amputation) was performed (Figure 3(b)). One week postoperatively, the stump was resurfaced with a free latissimus dorsi musculocutaneous flap with a split-thickness skin graft following histological confirmation of adequate surgical margins (Figure 3(c)).
Histological findings. (a) Proliferation of spindle cells with abnormal mitotic activities reminiscent of conventional malignant schwannoma (hematoxylin-eosin, x400). (b), (c) Epithelioid features of round-to-polygonal or rhabdoid cells with cellular atypia resembling malignant melanoma (hematoxylin-eosin, x400). (d) Immunohistochemical staining demonstrating strongly positive for S-100 protein.
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Histologically, the lesion consisted of two components: proliferation of spindle cells with some differentiation to nerve cells, reminiscent of conventional malignant schwannoma (Figure 4(a)), and epithelioid proliferation of round-to-polygonal or rhabdoid cells with hyperchromatic nuclei, reminiscent of malignant melanoma (Figures 4(b) and 4(c)). Tumor cells stained positive for S-100 protein and negative for HMB45 (Figure 4(d)).
Ten weeks after the first operation. (a), (b) Development of multiple lung metastases (M1, M2, M3).
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 Ten weeks after the first operation, computed tomography demonstrated the development of multiple small bilateral lung nodules (Figures 5(a) and 5(b)).
After two courses of adjuvant chemotherapy showing good response to all metastases. Note M3 was not recognizable.
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After two courses of the adjuvant therapy, follow-up computed tomography revealed a good response to all abnormal shadows; however, two lesions in segment 8 and one in segment 10 of the left lung field were still observable (Figures 6(a) and 6(b)).
Twelve months after the first operation. All metastatic lesions were eliminated through the chemotherapy and thoracic surgery.
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At the 12-month followup after radical surgery of the primary tumor, during which time four courses of adjuvant chemotherapy and a thoracic surgery were added, no signs of local recurrence or metastasis were observed (Figures 7(a) and 7(b)).
Clinical view at 12 month postoperatively.
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fig8
The patient maintained ambulation without a brace (Figure 8).