Rev Nefrol Dial Traspl. oct.-dic. 2020; 40(4):352-355

Retroperitoneal angiomyolipoma

IMÁGENES EN NEFROLOGÍA

Retroperitoneal angiomyolipoma mimicking adrenal cortical neoplasm. An unusual localization

Angiomiolipoma retroperitoneal que simula una neoplasia cortical suprarrenal. Una ubicación inusual

Murat Zor ORCID , Orhan Demir, Ibrahim Yavan, Ferhat Cuce, Mesut Gurdal

Recibido en su forma original: 3 de julio de 2020
Aceptación final: 26 de agosto de 2020

Cómo citar este artículo (How to cite this article): Zor M, Demir O, Yavan I, Cuce F, Gurdal M. Retroperitoneal angiomyolipoma mimicking adrenal cortical neoplasm. An unusual localization. Rev Nefrol Dial Traspl. 2020; 40(4):352-5.

INTRODUCTION

Angiomyolipoma are relatively rare benign mesenchymal neoplasms that derive from perivascular epitheloid cells.⁽¹⁾ These tumors may occur in a sporadic form or as a part of systemic diseases especially with tuberosclerosis.⁽²⁾ Compatible with its name, tumor consists of three components: smooth muscle cells, adipose tissue, and blood vessels. It is mostly seen in kidney, and rare extrarenal lesions mostly involve liver.⁽³⁾ Extrarenal retroperitoneal angiomyolipomas (ERAML) are extremely rare. It poses a diagnostic problem by mimicking other retroperitoneal tumors.

In our current study, we reported an AML located adjacent to left adrenal gland mimicking adrenal neoplasm.     

CASE HISTORY

A 53-year-old female patient was referred to our outpatient clinic with an incidentally diagnosed left adrenal mass. Her medical history revealed breast carcinoma, dysritmia and hypertension. She underwent mastectomy 9 years ago and was on follow-up with no recurrences. She was not also taking any medication for breast cancer. Initially she admitted to the chest disease clinic with dyspnea and cough and her chest tomography revealed a left 3 cm solid adrenal mass. A full adrenal biochemical workup was performed (24 hour VMA: 2,85 mg/day; 24 hour normetanephrine 187 mg/day; 24 hour metanephrine: 91.24 mg/day; noradrenaline: 26.56 mg/day; plasma renin activity: 3.06; cortisol dexamethasone 0.533; DHEA-S: 142mg/dL; aldosterone: 5.91 ng/dL). There was no sign for a hormonally active adrenal lesion. Adrenal MRI, and 18F-fluoro-deoxyglucose (FDG) PET/CT were performed. Adrenal MRI revealed a 35X28 mm lesion that was suggestive of an adrenocortical carcinoma or a metastatic primary tumor. (Figures 1 and 2)

Figure 1. Heterogeneous mass is seen that is of high signal on T2 sequences

Figure 2. Heterogeneous circumferential contrast enhancement is seen with administration of gadolinium. There was no macroscopic fat within the lesion

FDG PET/CT demonstrated an abnormal FDG accumulation within the mass which was in the left adrenal region. Maximum standardized uptake value [SUVmax] 2.6 g/mL.

Due to her previous history of breast cancer and imaging properties, the initial diagnosis is thought to be metastatic adrenal tumor or primary adrenal carcinoma. After written constent taken from the patient, she underwent left sided laparoscopic adrenalectomy. A well- shaped spherical encapsulated ~3.5 cm solid adrenal mass separate from the left kidney was resected. (Figure 3)

Figure 3. Macroscopic view of the resected specimen

The lesion was surgically seemed to be related with adrenal gland and did not worry us for a non-adrenal lesion.  On the other hand, macroscopic evaluation of the specimen revealed 2.5 cm well shaped mass adjacent to the adrenal gland. The whole specimen was nearly 6x3x2.5 cm. The histopathological examination revealed that the lesion was angiomylopoma and consisted of mature adipose tissue, thick-walled blood vessels and smooth muscle in different proportions (Figures 4 and 5). HMB-45 and Desmin antibodies also used immunohistochemically to confirm the diagnosis. 

Postoperative period was uneventful, and the patient discharged on postoperative 2^nd day. Her postoperative 1st year follow-up was also insignificant.

Figure 4. Histopathological examination demonstrating the distinction between tumor (on the right side) and adrenal gland (on the left side) (x40)

Figure 5. Histopathological view of the adipose structures and thick walled blood vessels (x100)

DISCUSSION

AMLs are uncommon lesions of perivascular epitheloid cells. Its incidence in general population is 0.013%.⁽⁴⁾ Dysmorphic blood vessels, epitheloid smooth muscle and adipose cells are three components of the tumor. The diagnosis is based on its radiological characteristics and histopathological properties. Immunohistochemical stains with HMB-45 and MAR-1/Mela A antibodies are also helpful.⁽⁴⁾ AMLs mostly occur in kidney but occasionally can be found in extrarenal sites. To date 30 cases of retroperitoneal origin has been reported but none of them included periadrenal adjacent area.⁽⁵⁾ Most of the reported cases were originated from the perinephritic region of the retroperitoneal area. As in our case most patients reported in the literature were female. Out of 30 cases reported in the literature 25 (84%) cases were female.⁽⁵⁾ Extrarenal retroperitoneal AMLs (ERAML) may present in a variety of clinical symptoms and signs. Most of them are related to the place and organ involved. In our case the patient had no symptoms or signs. Her chest clinic visit due to dyspnea and cough revealed an incidental adrenal mass. Imaging modalities for such adrenal lesions are crucial for preoperative diagnosis and guiding for surgery. Computed tomography and especially MRI are the most preferred imaging modalities for evaluating these lesions.⁽⁵⁾ Although imaging modalities guide surgeon fort preoperative evaluation, the value of histopathological examination is undeniable. In our case complete workup including biochemical workup and imaging modalities (adrenal MRI and FDG PET Ct scan) directed us for a metastatic adrenal tumor or an adrenocortical carcinoma. There was no sign for a non-adrenal lesion. So, we did not consider performing a percutaneous image-guided biopsy. The lesion was removed laparoscopically for histopathological examination.

CONCLUSION

ERAMLs are rare tumors and retroperitoneal region is an extremely rare location. The diagnosis can be challenging despite complete biochemical and imaging workup. Histopathological examination and complete resection with preserving the adjacent organs is crucial in the management of suspicious lesions.           

Conflict of interest: All authors declare that they have no conflict of interest. This study was not funded by any organization or committee.

BIBLIOGRAPHY

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