Klin Onkol 2018; 31(6): 448-452. DOI: 10.14735/amko2018448.
Background: Epithelioid angiomyolipoma (EAML) of the kidney, in contrast to classic benign renal angiomyolipoma, is a rare mesenchymal neoplasm with malignant potential. Representing a member of the perivascular epithelioid cells (PEComa) tumor family arising from the perivascular epithelioid cells, its accurate diagnosis and therapeutic approach remains challenging. Methods: We report a case of a patient with malignant EAML, initially treated as renal cell carcinoma (RCC) at our institution. In this paper, we briefly summarize current status of clinical and histopathological knowledge of renal PEComas with metastatic potential and reconsider the diagnostic and therapeutic approach in this particular case to highlight the risk of misdiagnosis, malignant potential of renal PEComas and to demonstrate an unexpected treatment response. Results: The patient in our case was diagnosed with chromophobe RCC with sarcomatoid features. She underwent a radical nephrectomy and epinephrectomy with a satisfactory postoperative history. Local recurrence urged chemotherapy commencement with sunitinib in the first line, and shortly afterwards, the patient was enrolled in a clinical trial with everolimus, with an extraordinary favorable treatment response for 30 months. Following the extirpation of single abdominal nodularity after 36 months of treatment with mTOR inhibitor, and proceeding the everolimus administration, the disease slowly progressed to the right liver lobe, resulting in right hemihepatectomy in another 24 months. The immunoprofile of liver metastases with positive staining of melanoma markers and smooth muscle markers induced the revaluation of the primary tumor and abdominal nodularity specimen to an invasive EAML of the kidney. Further disease progression was unavoidable despite several chemotherapy regimens, and the patient died 104 months after primary diagnosis. Conclusions: Renal tumors with adverse radiographic and histopathological features should become candidates for immunohistochemical staining as its omission frequently leads to a misdiagnosis, as showed in our case report. Atypical treatment response might suggest a possibility of a diagnostic mistake and should lead to reevaluation of the diagnostic and treatment process in the particular patient.
