Medical Analysis Report

I. Imaging Findings

According to the provided ultrasound and CT images, a soft tissue mass is observed in the subcutaneous soft tissue of the left calf:

• On ultrasound: A localized hypoechoic-to-isoechoic nodular lesion with relatively clear boundaries and heterogeneous internal echoes. The surrounding soft tissue structure remains largely intact.
• On CT images: A relatively dense mass within the soft tissue, with a slightly different density compared to nearby tissues. Visible soft tissue silhouette and septation, no obvious adhesions to surrounding muscles, and no significant osseous destruction.
• The lesion appears nodular or lobulated, exhibits mild enhancement in some areas, and there is no obvious edema or exudation surrounding it.

Overall, the imaging suggests a benign, nodular lesion located in the soft tissue layer of the left lower limb.

II. Potential Diagnoses

Combining the patient's clinical history (60-year-old male with a painless, mobile subcutaneous mass), the imaging characteristics (subcutaneous site, benign appearance), and histological indications, the differential diagnoses include:

1. Nodular Fasciitis
   This lesion is often composed of rapidly proliferating fibroblasts. It can appear as a rapidly growing mass yet is usually benign. Pathological features often include abundant fibrous tissue, myxoid stroma, and a vascular network.
2. Desmoid Tumor or Fibromatous Lesion
   These can appear similar to nodular fasciitis on imaging or early pathological examination but often demonstrate more aggressive behavior, less well-defined margins, and slower growth.
3. Fibrosarcoma or Other Malignant Soft Tissue Tumors
   These also involve proliferation of fibroblasts. Cellular atypia, mitotic figures, and imaging features suggesting invasion must be evaluated to rule out malignancy.

III. Final Diagnosis

Taking into account the patient's age (60 years), clinical presentation (painless, mobile subcutaneous nodule), imaging findings (a well-defined soft tissue nodule lacking malignant signs), and histological exam results (fibroblast components with abundant myxoid matrix arranged in fascicles, lacking significant atypia), the most likely diagnosis is:

Nodular Fasciitis

If there is any doubt or rapid growth of the lesion, further immunohistochemical testing or biopsy confirmation is recommended.

IV. Treatment Plan and Rehabilitation

1. Treatment Strategy
   • Most nodular fasciitis cases are self-limiting. Observation can be considered if the mass is stable or shrinking; surgery may not be necessary.
   • If the mass enlarges significantly or causes pain or functional impairment, surgical excision is an option. A local resection is usually curative.
   • Postoperative pathology should be performed to exclude malignancy.
2. Rehabilitation/Exercise Prescription
   • Early Postoperative Phase: Focus on incision healing and prevention of scar adhesions. Perform gentle passive limb movements, avoiding excessive pulling on the wound.
   • Recovery Phase: Gradually increase joint range of motion and muscle strength training. Aim for 3–4 sessions per week of low-intensity stretching and strengthening exercises (e.g., leg lifts, light resistance band training), each lasting about 15–20 minutes.
   • Consolidation Phase: If limb function has recovered well, engage in moderate-intensity exercise such as brisk walking or cycling 3–5 times a week for at least 30 minutes each session. Adjust the intensity based on individual responses.
   • Throughout the entire process, monitor for unusual swelling or pain around the lesion or surgical site. If discomfort or signs of recurrence arise, seek medical attention promptly.

Following the FITT-VP principle (Frequency, Intensity, Time, Type, Volume, Progression), exercise intensity and duration should progress from low to moderate in a planned, gradual manner. Always stay within a comfortable range, avoiding pain or excessive discomfort during activities.

Disclaimer: This report is for reference only and should not be considered a definitive diagnosis or treatment for any medical condition. The specific treatment plan should be based on the patient’s actual condition and professional medical evaluation. If any questions or new symptoms appear, please consult an orthopedic specialist or relevant doctor promptly.