We present a clinical case of a 48-year-old man who complained of pain and swelling of a soft tissue mass in the foot with one year of evolution.
We performed an X-Ray and found an extremely calcified lesion in the plantar foot (Figure 1).
Scintigraphy showed an increased uptake of the radiotracer (Figure 2).
CT demonstrated a heterogeneous soft-tissue mass showing areas of enhancement and also calcifications (Figure 3 and 4).
T1 MRI-weighted images showed a prominently heterogeneous soft-tissue mass (Figure 5), while T2-weighted images identified areas of hight intensity signal (Figure 6). With MRI intravenous contrast a heterogeneous enhancement was evident (Figure 7).
Biopsy guided by CT to the more calcified component was performed (Figure 8).
Synovial sarcoma is an aggressive soft tissue tumour that can occur at any age but most frequently between 15-40 years old [1]. It has a similar incidence in male and female gender [2] and represents about 10% of all soft-tissue sarcomas [3].
It does not seam to have a synovial origin. In fact, it has epithelial markers and only a small number of cases originate within a joint, with the majority of these tumours taking place adjacent to a joint [4]. Although it affects any part of the body, it occurs most commonly in the inferior limbs, with an increased prevalence in the popliteal fossa.
It usually presents as a mass that is noted by the patient. Most of the times, it is very indolent and has a slow growth rate. Nonetheless, it is a high-grade tumour with a considerable number of local recurrence and distant metastasis, mostly in the lung [2].
X-ray, CT and ultrasound can play an important role in characterizing this lesions, specially due to their great accuracy to detect the calcifications that are present in 30% of al cases [5]. Calcifications in rare cases, as in the one we report, can have extensive osteoid mineralization[5]. Around 11-20% of the patients have erosion of the bone or periosteal reaction [1], which can be detected in CT and X-Ray. However MRI is the gold standard not only for the diagnosis, but also for planning the surgery.
On MRI, the lesion can manifest as a heterogeneous mass mostly due to hemorrhage, necrosis, calcified and fibrotic tissue.
After the contrast injection the lesion usually shows enhancement [1] which can be evaluated both on CT and MRI.
Biopsy allows diagnostic to be made. Biopsy to the more superficial soft tissue component was primarily guided by ultrasound but, due to the fact that the pathological anatomy was inconclusive, we than performed biopsy of the more calcified component guided by CT.
Surgery for excision of the mass is currently the Gold standard treatment. However, when free margens are not achieved, than amputation should be considered [1]. Adjuvant therapie play an importante role when it comes to treatment: chemotherapy should be an option for the metastatic or residual disease, and radiation therapy, on the other side, can be important in two situations: previously to surgery, when one thinks negative margins will not be achieved or, after surgery, when one comes across positive margins [1].
Synovial sarcoma
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Based on the provided X-ray, CT, and MRI images, the following findings can be observed:
• A distinct mass-like lesion is visible in the soft tissue of the dorsum of the foot, showing relatively blurred margins and notable local soft tissue thickening.
• X-ray and CT demonstrate multiple patchy calcifications/ossification-like high-density areas within the mass, with local bone erosion or thinning of the cortical bone, suggesting aggressive behavior.
• On MRI, the lesion exhibits a markedly heterogeneous signal, possibly with cystic changes, necrosis, and potential hemorrhagic zones. T2-weighted images show partially hyperintense areas; irregular signals are also noted in the surrounding soft tissue.
• After contrast administration, the lesion shows significant enhancement with an uneven distribution.
Considering the patient's age (48-year-old male), clinical symptoms (foot pain with a soft tissue mass), and imaging findings (an invasive mass, internal patchy calcifications, heterogeneous MRI signals, and local bone erosion), the following differential diagnoses should be considered:
1) Synovial Sarcoma: Commonly occurs in young to middle-aged adults, often located around joints or in deep soft tissues. Imaging frequently shows calcifications, and it exhibits aggressive features consistent with this lesion.
2) Chondrosarcoma: A malignant tumor originating from cartilaginous tissue, which can show calcification or ossification on imaging; however, its typical locations and growth patterns differ somewhat from this case.
3) Malignant Fibrous Histiocytoma or Other Soft Tissue Sarcomas: These tumors can also present with a soft tissue mass and local bone erosion, though calcification is generally less common. Pathological examination is necessary to exclude these possibilities.
Based on the patient's clinical symptoms, imaging findings (prominent soft tissue mass, evident calcifications, bone involvement), and biopsy results, the most likely diagnosis is: Synovial Sarcoma.
If the pathology report is not definitive, further histological and immunohistochemical studies are required for a final confirmation. However, given the current data, Synovial Sarcoma is the primary consideration.
(1) Treatment Strategy:
• Surgical Treatment: For confirmed Synovial Sarcoma, complete surgical resection (aiming for negative margins) is the mainstay of treatment. If achieving a clear margin is not feasible, a more radical surgical approach (e.g., amputation) might be necessary to minimize the risk of recurrence.
• Radiation Therapy: May be used preoperatively to shrink the tumor or postoperatively when margins are positive or if there is a high risk of residual disease, as an adjuvant treatment.
• Chemotherapy: For patients with distant metastases or those at high risk of recurrence, chemotherapy can be considered to control the disease. It may also be employed as an adjuvant treatment modality.
(2) Rehabilitation and Exercise Prescription:
• After surgical or combined treatment, rehabilitation should be tailored to the patient's specific condition and postoperative recovery status. The primary goals are to promote local blood circulation and maintain or restore joint function and muscle strength.
• Progressive Exercise Principles (FITT-VP):
• Frequency: Start with basic functional training 3–4 times a week in the early phase. Depending on wound healing and pain levels, short daily sessions can be added.
• Intensity: Begin with very light to moderate intensity, avoiding excessive load, then gradually increase resistance or repetitions.
• Time: Each session can start with 5–10 minutes, allowing breaks. As tolerance improves, it can be extended to 20–30 minutes.
• Type: Begin with passive movement of the ankle and metatarsophalangeal joints, joint mobilization exercises, gradually transitioning to light resistive exercises and full-body coordination training.
• Progression: As function improves, consider low-impact activities such as cycling or swimming. Weight-bearing exercises for the lower extremities should be conducted under the guidance of a qualified physical therapist.
• Volume and Progression Speed: According to the patient's tolerance and improvement in limb function, assess the weekly or monthly increases in training volume and intensity.
• Special note: If bone stability is compromised postoperatively or if skin flaps were used, ensure proper use of braces or protective devices to prevent excessive loading and reduce falls. Regular follow-up is essential to monitor local conditions and imaging changes, and to adjust the rehabilitation plan accordingly.
This report is a reference analysis based on the current imaging and clinical information. It does not substitute for an in-person consultation with a professional physician. Specific treatment plans must be tailored to the patient’s actual condition and should be devised by a specialist after comprehensive assessment.
Synovial sarcoma
