Medical Analysis Report

I. Imaging Findings

The patient is a 65-year-old female. During staging examinations for breast cancer, an incidental soft tissue mass was discovered in the buttock. Based on the provided CT and MRI images:

• CT Scan: The mass is located in the deep soft tissue layer of the buttock, with relatively clear boundaries, showing slightly low density, somewhat uneven compared to surrounding fatty tissue. No obvious signs of local invasion or osteolytic destruction were noted, although mild cortical pressure or focal indentation on bone cortex is observed.
• MRI Examination: On T1-weighted images, the lesion signal is slightly lower than that of normal mature adipose tissue, with a clear margin and uneven internal signals. On STIR (or fat-suppressed sequence), it is not completely suppressed, suggesting it may contain fibrous vascular septa or brown fat components. After contrast enhancement, fine intralesional vessels and fibrous septa exhibit enhancement, without a markedly thick wall or solid enhancing area.

The overall presentation of the mass is relatively benign, lacking obvious malignant features such as thick (>2 mm) septa, significant soft tissue infiltration, or local bone destruction.

II. Potential Diagnoses

Based on the patient’s history (previous breast cancer, but the buttock mass shows no marked invasiveness) and imaging findings (partial fat signal, prominent septa, and enhancement), the following differential diagnoses can be considered:

1. Lipoma: A common benign fatty tumor. On imaging, it usually shows a signal consistent with normal subcutaneous fat. On T1-weighted images it appears hyperintense and is usually completely suppressed on fat-suppression sequences, with few fibrous vascular septa or marked enhancement.
2. Hibernoma (Brown Fat Tumor): A rare benign tumor composed of brown adipose cells, characterized by a T1 signal slightly lower than mature adipose tissue. It is not completely suppressed on STIR fat suppression, often contains abundant fibrous vascular septa, and demonstrates notable vascular enhancement after contrast injection.
3. Well-Differentiated Liposarcoma: Although it often appears with fatty density, it commonly shows septa thicker than 2 mm or a solid nodular component, accompanied by local invasive features. In this case, no thick septa, suspicious malignant nodules, or aggressive changes were observed, though definitive exclusion would require histopathology.

III. Final Diagnosis

Ultrasound-guided biopsy and pathological examination confirmed that the tumor is composed of brown adipose cells (S100 positive on immunohistochemistry) and fibrous vascular tissue, consistent with a diagnosis of hibernoma. The patient then underwent complete surgical resection, with postoperative pathology showing no malignant components, confirming the final diagnosis of hibernoma.

IV. Treatment Plan and Rehabilitation

Treatment Strategy:

• Complete surgical excision is the main treatment for a confirmed hibernoma. In this case, the patient’s tumor was completely removed, and pathology confirmed clear margins with no malignant components.
• If surgical margins are clean and pathology confirms benign growth, no further radiotherapy or chemotherapy is generally required. However, patients with a prior tumor history or extensive lesions are advised to undergo regular imaging follow-ups.

Rehabilitation/Exercise Prescription (FITT-VP Principle):

• Frequency (F): Start with 3 sessions per week and gradually increase to 4–5 sessions per week to aid in restoring physical fitness.
• Intensity (I): Begin with low-intensity activities (e.g., walking on level ground or light resistance training), keeping the subjective experience at a level of no fatigue or slight exertion (RPE ~3–4). Increase gradually to moderate intensity as the patient’s condition improves.
• Time (T): Start each exercise session at 15–20 minutes and gradually extend to 30 minutes or more. Advise the patient to avoid overexertion, especially considering their recovery status after breast cancer treatment.
• Type (T): Combine aerobic exercises (e.g., walking, stationary cycling, light swimming) with low-to-moderate intensity resistance training. After buttock surgery, avoid direct pressure on the surgical site initially, and progressively add core and lower-limb strengthening exercises.
• Volume (V): The total weekly exercise volume should be individualized based on overall tolerance, with a gradual progression to 150 minutes of moderate-intensity aerobic activity plus 2–3 sessions of strength training.
• Progression (P): As the patient’s strength and tolerance improve, safely increase resistance training loads and aerobic exercise duration. Carefully monitor local postoperative healing, and consult a physician if any discomfort arises.

Since the patient is older and has a history of breast cancer, attention should be paid to bone density and cardiopulmonary function. Exercise should be increased gradually to avoid falls or overexertion. Regular follow-up of bone density, cardiopulmonary status, and primary tumor is recommended. Adjust the plan promptly if any abnormalities occur.

Disclaimer

This report is provided as a reference based on current imaging and pathological information. It does not replace an in-person clinical diagnosis or the individualized opinion of a professional physician. Please seek continued care and rehabilitation guidance under the supervision of a qualified medical professional.