個案報告：後腹腔良性血管肌肉脂肪瘤癌化為惡性去分化脂肪肉瘤

陳柏翰¹、林文榮^1,2、陳建志^1,2,3

¹台灣基督長老教會馬偕醫療財團法人馬偕紀念醫院 泌尿科；²馬偕學校財團法人馬偕醫學院；³馬偕學校財團法人馬偕醫護管理專科學校 化妝品應用與管理科

A case report: Retroperitoneal angiomyolipoma with malignant progression to dedifferentiated liposarcoma

Bo-Han Chen¹, Wen-Rong Lin^1,2, Marcelo Chen^1,2,3

Department of Urology, MacKay Memorial Hospital, Taipei, Taiwan¹; School of Medicine, MacKay Medical College, New Taipei City, Taiwan²; Department of Cosmetic Applications and Management, MacKay Junior College of Medicine, Nursing and Management, Taipei, Taiwan³

Background:

Liposarcoma is the most common malignancy in retroperieoneal soft tissue. [1] It is usually classified into five category including myxoid, welldifferentiated, round cell, dedifferentiated and pleomorphic type according to its morphology. However, a dedifferentiated liposarcoma of the retroperitoneum is an extremely rare tumor. [1] Dedifferentiated liposarcomas are high-grade with high propensity for local recurrence and metastasis. [2] Since there are lots of other diagnoses similar to dedifferentiated liposarcoma, preoperative biopsy is recommended and does not negatively impact survival. [3] With definite pathologic diagnosis, surgical resection is considered to be standard treatment of dedifferentiated liposarcoma. [4] We hereby present a 71-year-old patient, who reported a growing retroperitoneal mass which was resected and diagnosed as benign angiomyolipoma previously and had malignant progression into dedifferentiated liposarcoma after four years follow up.

Case presentation:

A 71-year-old gentleman came to our outpatient clinic with the chief complaint of left abdominal palpable mass for a few weeks. He had experienced robotic assisted enucleation of left retroperitoneal tumor 4 years ago. The pathologic result at that time was angiomyolipoma. He had regularly follow up at local clinic in these years after that operation. (shown in Fig. 1)

However, he found himself having a palpable mass at left abdominal without tenderness recently. CT image found a huge mass (around 16cm) at left posterior para-renal space abutting kidney with anterior displacement of left kidney, encasement of left ureter & possible psoas muscle involvement, favoring malignancy. (shown in Fig. 2) Most of lab data including tumor markers were within normal range. Bone scan showed: (1) urine stasis in the left renal pelvis is noticed, compatible with a huge renal mass and (2) There is no other abnormality in the skeleton except for some stress or degenerative changes. CT-guided biopsy was done for tissue proof and sarcoma was diagnosed.

Under the impression of resectable retroperitoneum sarcoma, he was admitted for left nephrectomy and retroperitoneal exploration. Final pathological diagnosis was a dedifferentiated liposarcoma. The greatest dimension of sarcoma was 22.2cm. No venous or lymphatic invasion was noted. Surgical margin of resection was uninvolved. (shown in Fig. 3) It was a grade 2 lesion according to FNCLCC histologic grading system. With stable condition, he was discharged and told to have regular follow up in our outpatient clinic. According to guideline of National Comprehensive Cancer Network, postoperative radiotherapy should not be administered routinely for patient with R0 status. It has been three months postoperatively; there wasn’t any specific symptom or sign that implied the recurrence of tumor.

Conclusion:

Although an angiomyolipoma is thought to be a benign solid lesion, its possible malignant progression should be considered during the postoperative follow up. Preoperative biopsy can help us to rule out other systemic malignancies such as retroperitoneal lymphoma and metastatic germ cell tumors which may manifest as retroperitoneal masses. Pretreatment biopsy can also fortify our determination that surgery is beneficial to patient with dedifferentiated liposarcoma. To the best of our knowledge, surgical resection is the gold standard treatment to most liposarcomas unless patients’ condition is not qualified to operation. It seems to have good surgical result in our case.