Solitary contralateral adrenal metastasis of renal cell carcinoma 15 years following radical nephrectomy: A case report and review of literature

Highlights • A well-recognized phenomenon in RCC is late metastatic recurrence after nephrectomy.• Solitary contralateral adrenal metastatic recurrence of RCC is extremely rare.• Early diagnosis of adrenal metastasis is challenging because they are usually silent.• This paper is the delayed solitary metastatic recurrence of the renal cell carcinoma to the contralateral adrenal gland.


Introduction
Renal cell carcinoma (RCC) is known to metastasize to almost every organ. A well-recognized phenomenon in RCC is late metastatic recurrence after nephrectomy which is arbitrarily defined as more than 10 years. This could happen even in early stages of RCC when it has been completely removed. Lungs, abdomen, bones, and brain are among the most common metastatic sites [1,2]. However, isolated adrenal metastasis from RCC is uncommon. The incidence of solitary ipsilateral and contralateral adrenal metastasis is 3% and 0.7% respectively in patients who have underwent radical nephrectomy. Good prognostic signs include an early stage and low grade tumor with a long interval from the diagnosis to the development of metastasis [3]. In line with the SCARE criteria [4]. We here present a case of metastatic recurrence of RCC to the contralateral adrenal gland 15 years after radical nephrectomy.   arranged in sheets. The picture was consistent with renal cell carcinoma, Grade II Fuhrman nuclear characteristics, confined to the capsule, neither pelvicalyceal nor vascular invasion was found (pT1bN0M0). Postoperatively she did not receive immunotherapy or chemotherapy. Apart from her hypertension which was well controlled with amlodipine and valsartan, subsequent clinical and radiological follow up showed no local or metastatic recurrence till 5 years after the operation then she stopped her visits. On October 2016 an incidental mass was found in the right adrenal gland during a checkup visit for the status of her right solitary kidney. Abdominal and pelvic computed tomography scan was done, revealing a well-defined mass with a smooth outline in the right adrenal gland measuring 54 × 48 × 39 mm with a central necrosis. The density of the solid component was 38 HU. In dynamic study the solid component showed significant enhancement after intravenous contrast administration (Fig. 2). Thorough hematological, biochemical and hormonal investigations were performed; all were within normal range. The results of laboratory examination showed the adrenal mass to be nonfunctional. The condition was well clarified for the patient and consent was taken to do right adrenalectomy. Under general anesthesia, in left lateral position through right transcostal incision, right adrenalectomy was done (Fig. 3). No any perioperative complications were recorded and she was discharged home on 4 th post-operative day. Pathological examination revealed morphological and immunohistochemical findings in line with metastatic renal cell carcinoma, including positive staining for AE1/AE3, cytokeratin 7, vimentin, and CD10, and negative staining for CDX-2, inhibin, and synaptophysin (Figs. 4 and 5). During the last 2 years she has being on regular follow up. Whole body Positron Emission Tomography-Computed Tomography with fluorodeoxyglucose was performed, neither local nor metastatic recurrence was observed in any system.

Discussion
RCC has the characteristic features of late local and metastatic recurrence. In a large published series of patients with RCC treated with radical nephrectomy, those who survived more than 10 years had 11% chance of late recurrence. Therefore 10 year follow up by imaging is suggested, yet chance of recurrence exists even beyond this timeline, so special care should be maintained in patients with previous history of RCC [2]. Late metastatic contralateral adrenal recurrence from RCC is very rare and to the best of our knowledge, the literature contains only 5 cases similar to our case where metastatic recurrence happened after 10 years of radical nephrectomy (Table 1). This delayed metastatic recurrence can be explained by 2 reasons; First, slow growth of tumors, specifically in case of low grade tumors. Second, in some cases the detection of metastasis will be delayed due to failure of regular imaging follow up. Both of these points were present in our case [5]. Early diagnosis of adrenal metastasis is challenging because they are usually asymptomatic both anatomically and functionally, although on rare occasion the patient may present with symptoms and signs of adrenal insufficiency. So the main means to diagnose these lesions are regular imaging during the follow up period [1]. However it is difficult to determine whether the mass is a primary adrenocortical carcinoma, benign adrenal adenoma or metastasis through imaging studies. The presence of a well vascularized solitary adrenal mass

Table 1
Literature summary of contralateral adrenal metastasis from renal cell carcinoma more than 10 years after radical nephrectomy. with normal hormonal studies is more suggestive of metastatic lesion rather than primary adrenal mass. In 82% of the reported CAM cases diagnosis was made through CT scan, thus it is the imaging of choice [3]. Similarly in our patient the findings in CT scan were consistent with adrenal metastasis. The only known effective treatment in patients with limited metastasis is surgical removal that improves 5 year survival rate by 29 to 35%. This approach is also amenable to solitary adrenal metastasis [6]. Although laparoscopic technique is regarded as the standard of care in cases of small adrenal mass, however we did open adrenalectomy due to limited experience of laparoscopy at our center.

Conclusion
Solitary contralateral adrenal metastatic recurrence of RCC is extremely rare event. It can occur late after radical nephrectomy. CT scan with contrast is the imaging of choice that helps in diagnosis of adrenal metastasis. Surgical removal of CAM is a wise option in these cases that may improve survival.

Conflicts of interest
There is no conflict of interest.

Funding
None to be stated.

Ethical approval
Approval has been given by Ethical committee of University of Sulaymanyiah.

Consent
Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.