腎上腺和後腹腔惡性血管周圍上皮樣細胞瘤的侵襲性表現 - 案例報告

許程皓¹、張延驊^1,2、黃志賢^1,2
1臺北榮民總醫院泌尿部; ²國立陽明交通大學書田泌尿科學研究中心

An aggressive presentation of adrenal and retroperitoneal

malignant perivascular epithelioid cell tumor (PEComa) - A case report

Chen-Hao Hsu¹, Yen-Hwa Chang^1,2, William J. Huang^1,2

¹ Department of Urology, Taipei Veterans General Hospital, Taipei, Taiwan

² Department of Urology, School of Medicine, College of Medicine and Shu-Tien Urological
Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan

Introduction: Perivascular epithelioid cell tumor (PEComa) is an extremely rare subtype of soft tissue sarcomas consisting of mesenchymal tumor cells with the estimated incidence of approximately 0.3 per 1,000,000. We report a case with an aggressive presentation of left adrenal and retroperitoneal malignant PEComa leading to rapidly-progressed inferior vena cava (IVC) tumor thrombus and intraoperative pulmonary tumor embolism.

Case presentation: A 68-year-old woman with no significant medical history, had an incidental finding of Lt suprarenal mass lesion by Sono at health checkup in May, 2023. The computed tomography (CT) scan revealed a heterogeneously enhancing tumor (8.9 x 7.4 cm) at the left suprarenal region, attaching to the upper pole of the left kidney with tumor thrombus at the retro-aortal renal vein (Fig. 1 & 2). She later developed left flank soreness and visited the emergency department at an outside hospital where CT-guided tumor biopsy was performed with pathology report as malignant perivascular epithelioid cell tumor (PEComa). Surgery was recommended and she visited our Urology Clinic for a second opinion. And, she was then admitted for the scheduled operation. A follow-up CT before surgery disclosed progressive change with increased size of the mass to 9.2 cm, abutting the upper pole of left kidney, pancreatic tail, spleen, and aorta; with tumor thrombosis in left renal vein and IVC was also noted (Fig. 3).

The operation of debulking resection of the tumor with left nephrectomy, and para-aortic lymph nodes dissection was performed. The Lt renal vein with tumor thrombus was transected at the hilum level due to an extraordinarily stiff texture of the tumor and unrecognizable renal vessels. Right ventricular dilatation and strain with cardiogenic shock was disclosed by the intraoperative transesophageal echocardiography (TEE), and acute pulmonary embolism due to the tumor thrombus was highly suspected to be. The cardiovascular surgeon was consulted, and a venoarterial extracorporeal membrane oxygenation (VA ECMO) was placed, and preplanned renal vein and IVC thrombectomy was aborted. The post-operative CT disclosed embolism at the right main pulmonary artery and inferior branch of the left pulmonary artery (Fig. 4). Emergent surgery of bilateral pulmonary artery embolectomy was performed the next day. An 8.0 x 2.0 cm thrombus from the right main pulmonary artery, and a 3.0 x 1.0 cm thrombus from the inferior branch of the left pulmonary artery was removed respectively. With significant improvement of right ventricular dilatation after the surgery, VA ECMO was weaned post-operatively.

The final pathology of the resected tumor confirmed malignant PEComa from the retroperitoneum with kidney, adrenal gland invasion and regional lymph nodes metastases as well as bilateral pulmonary artery tumor thrombi involvement. The microscopic findings of the tumor showed proliferation of epithelioid cells with eosinophilic cytoplasm. By immunohistochemical stains, the tumor cells were positive for cathepsin K, while being negative for CK, SF1, a-inhibin, melan A, HMB45, GPNMB, synaptophysin, calretinin, GATA3, PAX8, p63, SMA, HHF35, desmin. TFE3 expression was equivocal. p53 was overexpressed.

The patient had an uneventful recovery and adjuvant chemotherapy and local radiotherapy was recommended at MDT tumor boards, however the patient declined initially. Unfortunately, she had local tumor recurrence and liver metastasis at two months following surgery. And she then underwent systemic chemotherapy (ifosfamide + epirubicin) and local radiotherapy (60Gy/25Fx) to the tumor bed. She developed progressive lower limbs weakness in Feb, 2024, and spine MRI at ER revealed multiple spine metastases with T8-10 cord compression and paraplegia. Total laminectomy (T8-10) with tumor removal was performed afterwards with post-operative fair neurological function recovery.  

Discussion:

PEComas are a group of mesenchymal tumors consisting of epithelioid cells or spindle cells around small blood vessels [1], and they encompass subgroups of tumors including angiomyolipoma (AML), clear-cell “sugar” tumor (CCST) of the lung, lymphangioleiomyomatosis (LAM), clear-cell myomelanocytic tumor of the falciform ligament, and clear-cell tumors of other visceral organs such as pancreas or rectum. PEComas are more often diagnosed in middle age with a 7 to 1 female to male ratio [2]. They most frequently originate from the uterus and retroperitoneum, while they can also occur in the kidney, lung, or liver [3]. Most of the PEComas are benign in nature with good prognosis; malignant cases are rare, however, they often present with aggressive local recurrence and distant metastasis [4]. The high-risk features of the PEComas defined by Folpe et al. include size more than 5 cm, infiltrative growth pattern, high nuclear grade and cellularity, mitoses above 1/50 HPFs, necrosis, and lymphovascular invasion. If two or more high-risk features are present, it is classified as malignant PEComas [5].

Few cases of malignant PEComas have been reported in the adrenal gland. Battistella et al. presented a case with an adrenal incidentaloma who was initially diagnosed as adrenocortical adenoma by histopathology after surgical resection, but later complicated with bone metastases and disc compression status post emergent laminectomy with pathology finding of metastasized PEComa and a pathological review of the adrenal mass revising the diagnosis to adrenal PEComa [6]. Due to the scarcity of cases reported, there is currently no criteria established for the resectability of PEComas. However, complete surgical excision of the tumor with negative margin remains as the mainstay of treatment for locally advanced malignant PEComas. For unresectable or metastatic malignant PEComas, chemotherapy, mTOR inhibitors and VEGFR inhibitors may be considered. [7].

Conclusion:

This case demonstrated a rapidly-progressed presentation of the adrenal and retroperitoneal malignant PEComas, underscoring the clinically aggressive behavior of them and the importance of keeping them as a differential diagnosis among adrenal neoplasm despite diagnostic challenges.