Late local, peritoneal and systemic recurrence of renal angiomyolipoma: A case report

Abstract

Renal angiomyolipoma (AML) is a relatively rare tumor that is generally considered as merely benign. However, epithelioid AML (EAML), an uncommon subtype, is associated with potentially malignant behavior. We herein present the case of a 60-year old male patient who had undergone left nephrectomy with left adrenalectomy and lymphadenectomy for a renal tumor 12 years earlier, and presented to our hospital with dull abdominal pain. The histology report after the previous surgery had revealed an AML of the left kidney with a maximal diameter of 17 cm. Imaging studies demonstrated a large tumor of 13 cm in diameter in the area of the resected kidney, as well as hepatic and peritoneal metastases. Computed tomography-guided core needle biopsy of the mass and revision of the histology of the nephrectomy revealed an EAML. Four years after a two-stage resection of the recurrences the patient is in excellent condition and free of disease. From this case report and the literature review on EAML, it appears that correct histological diagnosis of this subtype of renal AML is crucial. Erroneous diagnosis of simple renal AML instead of EAML may lead to insufficient postoperative management. Clinicians should be aware of the malignant potential of EAML and the need for long-term follow-up. As effective surgical and emerging medical treatment options are available, timely detection of recurrent disease may lead to improved outcome.

Keywords: metastatic disease; recurrence; renal epithelioid angiomyolipoma; treatment.

Figure 1.

(A) Axial contrast-enhanced CT image showing a heterogeneous, large mass, occupying the surgical bed. (B) Corresponding axial T2-weighted MRI revealed a heterogeneous signal intensity mass, with cystic/necrotic spaces, areas of hemorrhage exhibiting a ‘shading effect’ (arrow), with (C) matching hyperintensity areas on T1 fat-saturated, unenhanced 3D GRE image (arrow). (D) The MRI also showed heterogeneous enhancement of the predominately solid areas of the tumor (arrow) and (E) infiltration of the splenic capsule (arrow). GRE, gradient echo; MRI, magnetic resonance imaging; CT, computed tomography.

Figure 2.

(A and B) Histological re-examination of the primary tumor demonstrated characteristics of an AML, with proliferation of predominantly round to polygonal epithelioid cells with enlarged vesicular nuclei and prominent nucleoli (H&E staining; magnification, ×100). Histological examination of the locally recurrent EAML demonstrated (C) more extensive epithelioid characteristics with atypia (H&E; magnification, ×100), (D) invasion of the spleen (H&E staining; magnification, ×100) and expression of (E) Melan-A and (F) HMB-45 in tumor cells (magnification, ×200). H&E, hematoxylin and eosin; AML, angiomyolipoma; EAML, epithelioid AML.

Figure 3.

(A) Mesenteric infiltrating mass (arrow) exhibiting the same imaging properties as the locally recurrent mass, with (B) heterogeneity on sagittal T2-weighted MRI, with areas of necrosis and heterogeneous enhancement on axial T1 fat-saturated 3D GRE images. (C) Half-Fourier acquisition single-shot turbo spin-echo depicted moderately high signal intensity of the focal liver lesion in liver segment VIII, (D) restricting diffusion on diffusion weighted imaging, ADC map (arrow), suggesting malignant, metastatic liver lesion. GRE, gradient echo; ADC, apparent diffusion coefficient; MRI, magnetic resonance imaging.