Imaging appearance of renal epithelioid angiomyolipoma: A case report and literature review

Abstract

Rationale: Epithelioid angiomyolipoma (EAML) is an extremely rare disease. It commonly occurs in middle-aged females and mainly involves the kidney. Histological and immunohistochemical examination play important roles in differentiating EAML from renal cell carcinoma (RCC) and poor-fat angiomyolipoma (AML).

Patient concerns: Here, We report the imaging phenotype, as well as the pathological findings of a case of EAML in a 39-year-old female.

Diagnoses: Preoperative noncontrast computed tomography (CT) scan revealed a 6.0 × 5.2 × 7.0 cm soft tissue mass with necrosis, located in the left kidney. On contrast-enhanced CT images, aprogressive enhancement pattern was observed. CT angiography did not show any enlarged vessels or vascular malformation. Abdominal MRI showed a well-circumscribed solid mass with a heterogeneous signal on T1-weighted and T2-weighted images. Ultrasonography of the abdomen demonstrated a hypoechoic mass with abundant blood flow. This patient underwent radical nephrectomy. The pathologic diagnosis was EAML.

Interventions: This patient underwent operative resection of the tumor. The resection margins were negative for the neoplastic proliferation and no distant metastases were found. The patient did not receive advanced radiotherapy or chemotherapy.

Outcomes: Four months after surgery, the follow-up CT scan did not reveal any local recurrence or distant metastases.

Lessons: This case adds to the experience with EAML by summarizing its imaging characteristics as well as reviewing the literature. Additionally, we described the state-of-the-art management of the management of this rare tumor.

Figure 1

(A) Unenhanced CT scan shows a mass (white arrow) with necrosis (white triangle) in the left kidney. (B–D) On contrast-enhanced CT images, the tumor presents progressive and heterogeneous enhancement. CT = computed tomography.

Figure 2

CT angiography does not reveal any tumor feeding vessels or vascular malformation. CT = computed tomography.

Figure 3

(A–C) The tumor presents as low to high signal on T1WI and T2WI with slightly diffusion restriction.

Figure 4

Ultrasonography of the abdomen shows increased blood flow signal around the hypoechoic mass. LK = left kidney, M = mass.

Figure 5

(A) The tumour is comprised of the proliferation of predominantly epithelioid cells with granular eosinophilic cytoplasms (H&E, ×100). (B) Immunostain for human melanoma black 45 in tumor cells. (C) Immunohistochemical stain for Melan-A. (D) The proliferation index, expressed as a percentage of Ki-67 antigen-positive nuclei, is around 10%.