Epithelioid sarcoma with muscle metastasis detected by positron emission tomography

Abstract

Background: Epithelioid sarcoma is an uncommon high-grade sarcoma, mostly involving the extremities.

Case presentation: A 33-year-old man was referred to our institute with a diagnosis of Volkmann's contracture with the symptom of flexion contracture of the fingers associated with swelling in his left forearm. Magnetic resonance imaging (MRI) showed abnormal signal intensity, comprising iso-signal intensity on T1- and high-signal intensity on T2-weighted images surrounding the flexor tendons in the forearm. Diagnosis of epithelioid sarcoma was made by open biopsy, and amputation at the upper arm was then undertaken. [18F]-2-fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) detected multiple lesions with an increased uptake in the right neck, the bilateral upper arms and the right thigh, as well as in the left axillary lymph nodes, with maximum standardized uptake value (SUVmax) ranging from 2.0 to 5.5 g/ml. Magnetic resonance imaging confirmed that there was a lesion within the right thigh muscle which was suggestive of metastasis, even though the lesion was occult clinically.

Conclusion: Increased uptake on FDG-PET might be representative of epithelioid sarcoma, and for this reason FDG-PET may be useful for detecting metastasis. Muscle metastasis is not well documented in epithelioid sarcoma. Accordingly, the frequency of muscle metastasis, including occult metastasis, needs to be further analyzed.

Figure 1

Epithlioid sarcoma in the forearm. Flexion contracture of the fingers can be seen (A). Plain radiograph shows irregular surface of the ulna (B). MRI of the forearm shows an abnormal lesion with iso-signal intensity on T1-weighted image (top) and high-signal intensity on T2-weighted image (middle) (C). Enhancement with gadolinium can be seen on T1-weighted fat-suppression image (bottom) (C).

Figure 2

Epithelioid sarcoma in the forearm shows atypical epithelioid cells in sheets associated with tumor necrosis (right portion) (A). The neoplastic cells have nuclei and prominent nucleoli, with eosinophilic glassy cytoplasm (B). (Hematoxylin and Eosin original magnification; A, ×150; B, ×200).

Figure 3

Metastatic lesions of epithelioid sarcoma. FDG-PET identifies lesions with an increased uptake in the right neck (SUVmax; 4.6), right upper arm (SUVmax; 4.1 g/ml), left upper arm (SUVmax; 4.2 g/ml), right thigh (SUVmax; 5.5 g/ml) left thigh (SUVmax; 2.0 g/ml), back (SUVmax; 3.6 g/ml), and lower back (SUVmax; 4.6 g/ml), as well as the left axilla (SUVmax; 3.9 g/ml) (arrows) (A). CT with contrast medium shows a swollen axillary lymph node (B). Sagittal MRI section of the right thigh shows a nodular lesion associated with prominent longitudinal abnormal signal intensity on T2-weighted image (C). The nodular lesion shows iso-intensity on T1-weighted fat-suppression image (top), and heterogeneous high-intensity on T2-weighted image (middle) (D). Enhancement with gadolinium can be seen on T1-weighted fat-suppression image (bottom) (D).