Archives of Medicine and Health Sciences

CASE REPORT
Year
: 2016  |  Volume : 4  |  Issue : 2  |  Page : 222--224

Pure epithelioid angiomyolipoma of kidney in tuberous sclerosis patient: A case report and review of literature


Azar Naimi1, Maryam Riahinejad2, Fereshteh Mohammadizadeh1, Mehrdad Hosseinpour3,  
1 Department of Pathology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
2 Department of Radiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
3 Department of Surgery, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran

Correspondence Address:
Azar Naimi
Department of Pathology, School of Medicine, Isfahan University of Medical Sciences, Isfahan
Iran

Abstract

The majority of renal angiomyolipoma (AML) is sporadic, and occasionally it occurs in the background of tuberous sclerosis complex. Epithelioid AML (EAML) is an uncommon variant, with uncertain behavior. We present a case of tuberous sclerosis with right large renal tumor. The tumor revealed epithelioid cells accompanied by thick wall vessels and muscular bundles in all the sections; devoid of lipocytes. Immunohistochemistry confirmed the diagnosis of epithelioid perivascular epithelioid cell tumor. Pure EAML is a rare tumor with potential malignancy. Accurate diagnosis, especially differentiation it from renal cell carcinoma, is very important for proper management of the patient.



How to cite this article:
Naimi A, Riahinejad M, Mohammadizadeh F, Hosseinpour M. Pure epithelioid angiomyolipoma of kidney in tuberous sclerosis patient: A case report and review of literature.Arch Med Health Sci 2016;4:222-224


How to cite this URL:
Naimi A, Riahinejad M, Mohammadizadeh F, Hosseinpour M. Pure epithelioid angiomyolipoma of kidney in tuberous sclerosis patient: A case report and review of literature. Arch Med Health Sci [serial online] 2016 [cited 2022 May 25 ];4:222-224
Available from: https://www.amhsjournal.org/text.asp?2016/4/2/222/196201


Full Text

 Introduction



The majority of renal angiomyolipoma (AML) is sporadic, and occasionally it occurs in the background of tuberous sclerosis complex (TSC). Epithelioid AML (EAML) is an uncommon variant, with uncertain behavior.

Epithelioid AML is associated with tuberous sclerosis in more than 50% of cases. These tumors are related to loss of TSC genes, TSC1 (9q34) or TSC2 (16p13.3) which seem to have a role in the regulation of Rheb/mTOR/p70S6K pathway.[1]

Pure EAML is rare, and it is a challenging case in diagnosis for its similarity to renal cell carcinoma which has different management.

 Case Report



A 7-year-old girl with abdominal pain admitted to the hospital. On physical examination the pain was in a right lower quadrant of the abdomen and a large, firm, mobile mass was detected on palpation on lower paramedian, right side. Obstruction signs were not detected. Vital signs, including heart rate, blood pressure, and temperature were unremarkable, and all laboratory findings were within normal limits.

In her past medical history, she was the case of tuberous sclerosis since 4 months, and she was treated with gabapentin, acethazolamide, and sodium valproate for her seizure.

A few simple cysts were reported in her last computed tomography (CT) scan 3 years ago.

A spiral CT scan of the abdomen demonstrated multivariable hypodense masses (favor of cysts) in bilateral kidneys. Furthermore, a lobulated huge enhancible mass with necrotic center reported in the mid and lower part of the right kidney with extension to the midline of the retroperitoneum. The mass encompassed aneurysmal vessels accompanied by dilated right renal vein [Figure 1]. According to past patient history, AML was the first diagnosis.{Figure 1}

All other organs in the mediastinum or abdomen were unremarkable.

She was planned for surgery for radical nephrectomy. At the time of surgery, a large mass (approximately 20 cm × 9 cm × 6 cm) was observed in the right kidney place and was subsequently excised [Figure 2].{Figure 2}

Pathological analysis of the mass showed proliferation of admixture of smooth muscle cells, thick-walled vessels, and epithelioid cells [Figure 3].{Figure 3}

In Immunohistochemistry study, the epithelioid cells were negative for cytokeratin and were positive for HMB45 [Figure 4].{Figure 4}

Smooth muscle actin was positive in muscle cells and <1% of nuclei revealed positivity for Ki67 marker.

After 18 months follow-up, although the patient's seizures are not controlled, she has no new problem with her kidneys.

 Discussion



AMLs can be classified as classical AML and EAML. Classic AML is a triphasic tumor characterized by an admixture of fat, smooth muscle cells, and thick-walled vessels. The classic examples are often found incidentally and are relatively easy to identify on imaging studies because of the presence of fat in them.[2]

EAML can be further classified as atypical AML or malignant EAML.[1]

It also defined EAML as a potentially malignant mesenchymal neoplasm characterized by the proliferation of predominantly epithelioid cells.[3]

In different studies, various criteria defined as predictor of aggressive behavior of AML, these common in (a) >70% atypical epithelioid cells, (b) >2 mitotic figures/10 HPF, (c) atypical mitoses, and (d) necrosis; presence of three or more of the feature was highly associated with malignant behavior.[4]

Folpe et al. reported 26 cases of perivascular epithelioid cell tumors (PEComas), they observed a significant association between tumor size >5 cm, infiltrative growth pattern, high nuclear grade, necrosis and mitotic activity >1/50 HPF and subsequent aggressive clinical behavior of PEComas.[5]

Classic AMLs of the kidney are initially recognized at or before the age of 10 years in approximately 10%–15% of TSC cases. It is estimated that 25%–30% of all EAMLs present in the clinical setting of TSC.[6]

Our case was a pure epithelioid AML with relative 100% epithelioid cells, <5% lipid component accompanied by abnormal vessels. The most important point in correct diagnosis of this tumor was differentiating it from renal cell carcinoma, and it was not possible without applying immunohistochemistry study.

A few EAML are in reports, but pure form and in the setting of tuberous sclerosis is rare.

Of the 33 patients with follow-up data reported by Nese et al., five patients recurred with a mean time to recurrence of 32 months (range, 8–72 months).[7]

Aydin et al. detailed the pathologic characteristics and clinical outcomes of 194 renal AMLs. They found that EAML is indeed uncommon and seen in about 8% of renal AMLs. The mean epithelioid component was 51% (range: 10%–100%). Pure EAML with 100% epithelioid component is even rarer (2/194, 1%).[8]

Nese et al. analyzed the clinicopathologic parameters in a large series of 41 cases of pure EAMLs of the kidney, which we designate as pure epithelioid PEComas to contrast them from classic AMLs that are regarded by some as PEComas.

Nine patients had a history of associated tuberous sclerosis. Recurrence and metastasis were seen in 17% and 49% of patients; 33% of patients died of disease. Lymph node involvement was seen in 24% of patients; the liver (63%), lung (25%), and mesentery (18.8%) were the most common metastatic sites.[7]

Bleeker et al. evaluated all 234 cases of PEComa-not otherwise specified reported in the English literature, extracting information regarding diagnostic features, treatment approaches, and outcomes. Multivariate analysis of a number of variables evaluable for pathologic review was performed to refine preexisting risk stratification criteria. Primary tumor size ≥5 cm and a high (1/50 HPF) mitotic rate were the only factors significantly associated with recurrence following surgical resection.[9]

He et al. reviewed 437 consecutive renal AMLs with primary resection at three tertiary-care institutions with high nephrectomy volumes. Only tumors showing 80% epithelioid histology were included in this study. Twenty of these 437 (4.6%) were classified as EAML. The female to male ratio was 11:9, mean age 49 years, and mean tumor size 8.7 cm. Microscopic tumor necrosis was present in 10 (50%) tumors and mitotic activity (range, 1–5/10 high power fields) in 8 (40%); atypical mitoses were seen in only 1 (5%) tumor. With a mean follow-up of 82.5 months, 17 patients were alive with no-evidence-of-disease at the time of the last follow-up; two patients died of unrelated causes with no-evidence-of-disease, and one patient (5%) developed distant metastases.[2]

 Conclusion



EAML is a tumor with potential malignancy. Accurate diagnosis, especially differentiation from renal cell carcinoma, is very important for proper management of the patient.

According to close similarity, immunohistochemistry can provide sufficient confidence for accurate diagnosis.

Generous sampling and obsessive review of slides for detecting morphologies representative aggressive behavior are mandatory.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

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