Radiological Findings

Based on the provided X-ray and MRI scans, the following can be observed:

• A well-defined lobulated soft tissue mass is seen within the plantar soft tissue of the left foot.
• On the X-ray, cartilage-like calcifications are observed within and around the mass, partially presenting as ring or segmented calcifications. No obvious bony connection or significant bone destruction is noted.
• MRI shows heterogeneous signal intensities on T1 and T2 sequences, with mixed high and low signals in certain areas. The mass margins are clear, with no definite involvement of bone.
• No significant invasion into adjacent structures is noted. An old healed fracture is visible in the fourth metatarsal.

Possible Diagnoses

Based on the patient's clinical presentation (several months of plantar pain and swelling without a clear history of acute trauma) and the imaging findings (cartilage-like calcifications within the soft tissue mass, no obvious bony connection or destruction), the following diagnoses are considered:

1. Soft tissue chondroma
   Characteristics: A benign cartilaginous tumor arising in the soft tissues, sometimes accompanied by calcification or ossification; commonly found in the hands and feet. Radiologically, it often appears as a lobulated soft tissue mass with cartilage-like calcifications.
2. Synovial sarcoma
   Characteristics: Can exhibit calcification and typically occurs in individuals aged 30–40. On MRI, contrast enhancement is often more pronounced than in this case, and it can sometimes involve periarticular structures.
3. Heterotopic ossification / Myositis ossificans
   Characteristics: Often follows trauma or surgery. In early stages, it appears as a soft tissue mass. Later, a more regular zone of ossification forms. The pattern of calcification differs from that of cartilage.
4. Calcific myonecrosis
   Characteristics: Typically associated with severe trauma, multiple surgeries, or chronic ischemia. It manifests as band-like or layered calcification following the orientation of muscle fibers.
5. Extraskeletal chondrosarcoma
   Characteristics: A more malignant entity that can show calcification. Histologically, typical features of chondrosarcoma may be present. It generally grows faster, accompanied by pain and more aggressive appearances on imaging.

Final Diagnosis

Considering the patient’s age, clinical symptoms (a slowly growing soft tissue mass with pain for several months), local imaging findings (a soft tissue tumor-like lesion with cartilage-like calcifications and no obvious bone destruction), and histology/pathology results (showing cartilaginous tissue and partial ossification with no clear signs of malignancy), the most likely diagnosis is:

Soft tissue chondroma.

This condition is generally benign, with malignant transformation being extremely rare. If pathological findings suggest malignancy, extraskeletal chondrosarcoma should be ruled out. In this case, there is currently no evidence of malignancy based on histological examination.

Treatment Plan and Rehabilitation

Based on the diagnosis and local symptoms in this case, the following recommendations are provided:

1. Treatment Strategies
   • Surgical excision: Complete excision is typically performed for soft tissue chondromas. Postoperative monitoring is necessary, as local recurrence rates can reach 15–25%, though distant metastasis or malignant transformation is extremely rare.
   • If pain and functional impairment gradually subside after excision, regular follow-up is required, including imaging examinations to detect any local recurrence.
   • For patients who are not suitable candidates for surgery or decline surgery temporarily, conservative treatment (e.g., temporary pain management and physical therapy) can be considered based on clinical symptoms. However, surgical treatment is recommended if the tumor significantly affects foot function or causes pronounced pain.
2. Rehabilitation and Exercise Prescription

   Postoperative rehabilitation should be adjusted according to the patient’s wound healing, pain level, and activity capacity. In general, it follows the gradual FITT-VP principle (Frequency, Intensity, Time, Type, Progression, and Individualization):

   • Early Phase (1–2 weeks after surgery):
     • Mainly focus on wound care and static muscle strength exercises, avoiding heavy weight-bearing on the foot.
     • Within a safe range, perform gentle active movements of the ankle and toes to promote circulation.
     • Frequency: 1–2 sessions per day, each lasting about 10–15 minutes.
   • Mid Phase (2–6 weeks after surgery):
     • Gradually increase localized weight-bearing activities, such as walking with braces or crutches.
     • Emphasize foot joint range of motion and soft tissue stretching exercises to prevent adhesions or contracture of the plantar fascia and aponeurosis.
     • Frequency: 3–4 sessions per week, each session 15–20 minutes, adjusted according to tolerance.
   • Late Phase (6 weeks and beyond):
     • Gradually transition to walking without aids and moderate weight-bearing exercises, continuing stable training as tolerated based on pain levels.
     • Light balance and strength training under professional guidance can be introduced, such as resistance exercises for the small foot muscles or band exercises.
     • One or two sessions of moderate-intensity exercises per week (e.g., swimming, cycling), each lasting 20–30 minutes, can improve foot endurance and overall cardiorespiratory fitness.

   Throughout the rehabilitation process, close monitoring of foot pain and swelling is essential. In case of significant abnormalities or high-risk factors (such as fragile foot bones or poor cardiopulmonary function), prompt follow-up and adjustment of the training program are advised.

Disclaimer

The above report is a reference analysis based on the current information and cannot replace an in-person consultation or professional medical advice. If you have any questions or if your condition changes, it is recommended you promptly visit a hospital for further evaluation and treatment.