Renal Metastasis Arising From a Pulmonary Adenoid Cystic Carcinoma: A Rare Case Report and Literature Review

Abstract

Adenoid cystic carcinoma (ACC), a rare malignancy, typically originates in salivary glands and is rarely found in other locations. In this case report, we describe a 54-year-old male patient who was presented to the Urology Department of Yantai Yuhuangding hospital with right-sided waist pain. The patient underwent percutaneous ultrasound-guided biopsies of lesions in the kidney and lung, which were histologically confirmed as primary adenoid cystic carcinoma of the lung and metastatic renal adenoid cystic carcinoma, respectively. Given the presence of multiple metastases, the patient received systemic palliative chemotherapy, which was well-tolerated and effectively controlled the tumor. At the last follow-up, there was no evidence of tumor progression in the patient.

Introduction

Adenoid cystic carcinoma (ACC) is a rare yet highly invasive tumor that typically originates in secretory glands, including the minor salivary glands of the upper jaw, the parotid gland, and the submandibular gland. It can arise in other sites such as lacrimal glands, breast, skin, and vulva (Resio et al., 2018). Despite its slow growth, ACC is associated with poor outcomes, with a 10-year survival of less than 50%, regardless of its histologic grade (Piazza et al., 2021). ACC tend to recur and metastasize (Friedrich & Bleckmann, 2003). Pulmonary adenoid cystic carcinoma (PACC), previously referred to as the “columnar tumor,” is a rare and slow-growing neoplasm known for its indolent. PACC often metastasizes to regional lymph nodes, the lung, bone, liver, skin, and brain (Moran et al., 1994; Piazza et al., 2021; Turnbull et al., 1972). While kidney metastasis is recognized, it remains an infrequent site of dissemination (Freling et al., 2016). We present a case of a 54-year-old male who was diagnosed with PACC that had also metastasized unilaterally to the kidney, an exceptionally rare occurrence. Our aim in reporting this case is to emphasize its exceptional characteristics concerning the primary site (lung) and metastasis, and to underscore important considerations including differential diagnosis, effective treatment approaches, and the necessity for long-term follow-up in managing this rare malignancy.

Case Report

A 54-year-old male presented to the Urology Department of Yantai Yuhuangding Hospital due to persistent right-sided waist pain lasting for 1 month. The patient did not report any other associated discomforts, such as hematuria or swelling. Tumor marker testing yielded negative results.

An abdominal CT scan revealed a right kidney mass (Figure 1A). The abdominal enhanced CT scan revealed a 4.1 × 3.8 cm hypodense lesion in the mid-portion of the right kidney, which raised suspicion of a neoplasm. There was a slight increase in density noted in the local regions of the 12th thoracic, second lumbar, and first sacral vertebral bodies, which could not rule out the possibility of metastatic tumors. The right kidney mass exhibited slight enhancement in the arterial phase (Figure 1B), with a CT value of 45 ± 5 HU. The degree of enhancement in the venous phase (Figure 1C) was greater than that in the arterial phase, with a CT value of 60 ± 5 HU. Based on these findings, the patient was diagnosed with a tumor in the right kidney using CT imaging. A subsequent chest CT scan revealed an irregular nodule in the apical segment of the right upper lobe of the lung. This nodule measured approximately 2.9 × 2.7 × 3.0 cm, with a CT attenuation value of 33 ± 5 HU. It exhibited lobulated contours and short, fine spiculations, which raised suspicion of a pulmonary malignant tumor (Figure 1D).

Figure 1.

(A) Image of Computed Tomography Shows Right Kidney Space Occupying Lesions. Image of Contrast-Enhanced Computed Tomography Arterial (B) and Venous (C) Showing Right Kidney Mass With a Slight Enhancement. (D) Image of Computed Tomography Shows Pulmonary Space Occupying Lesions

The patient underwent a percutaneous ultrasound-guided biopsy of the renal lesion. Microscopically, tumor cells were arranged in typical cribriform, tubular, and focally solid growth patterns (Figure 2A). The IHC result revealed that tumor cells displayed a positive expression of receptor tyrosine kinase inhibitors, including c-Kit (CD 117), cytokeratin 7 (CK7), cytokeratin 34 beta E12 (34βE12), and epithelial membrane antigen (EMA). The tumor exhibited negative expression for thyroid transcription factor 1 (TTF1), thus confirming the diagnosis of ACC. There was no staining observed for smooth muscle actin (SMA), S100 protein and protein 63 (P63). The proliferation index, Ki-67, was estimated to be 20%.

Figure 2.

(A) Metastatic Adenoid Cystic Carcinoma to the Kidney, Showing the Characteristic Cribriform Histological Pattern of Growth. (B) Puncture Pathology of Adenoid Cystic Carcinoma of the Lung (Hematoxylin-Eosin Stain)

The PET-CT examination indicated suspicions of malignant tumors in the posterior segment of the right upper lobe of the lung and the middle-lower portion of the right kidney. In addition, there was elevated FDG metabolism observed in multiple areas across the skeletal system, accompanied by partly increased bone density, indicating the potential presence of metastatic lesions.

The patient underwent percutaneous ultrasound-guided biopsy of the pulmonary lesion. The pathological examination revealed a malignant lung tumor, with the possibility of ACC not being ruled out (Figure 2B). The IHC assay demonstrated positive expression of CK7, CK8/18 (glandular epithelium), P63 (myoepithelium), and partial expression of CD117 and TTF-1. It showed negative expression of Dog-1, confirming the concurrence presence of ACC. Ki-67 was estimated to be approximately 20% in the hotspot area. The IHC results revealed extremely low expression of PD-L1 in the patient. This indicates that immune checkpoint inhibitors might not be an effective treatment for this case.

Due to the presence of multiple metastases, surgical intervention was not deemed suitable. Therefore, in November 2022, the patient commenced systemic palliative chemotherapy. The treatment regimen consisted of monthly administrations of 400 mg of albumin-bound paclitaxel and 600 mg of carboplatin, complemented by zoledronic acid to address bone metastasis treatment. The patient exhibited good tolerance to this therapeutic approach, and the treatment effectively controlled the tumor. At the most recent follow-up, there was no evidence of tumor progression in the patient.

Discussion

Renal metastasis typically arises from hematogenous dissemination of primary tumors, and it commonly manifests as multiple or multifocal lesions. In most cases of metastatic renal carcinoma, clear symptoms such as hematuria are not observed. In the present case, the patient did not display prominent clinical symptoms apart from mild discomfort in the right flank region. This case was unique in that the patient exhibited a solitary metastasis located in the mid-portion of the right kidney, making the clinical diagnosis of the mass more challenging.

An accurate and early diagnosis plays a crucial in the treatment and prognosis of ACC patients. CT and bronchoscopy examination are important for diagnosing ACC and planning treatment strategies. ACC typically exhibits invasive growth with perineural invasion and has a propensity to metastasize to the lungs, bones, liver, and brain (Junejo et al., 2019; Philippou et al., 2021). However, the occurrence of ACC to the kidneys is exceptionally rare. In primary renal carcinoma, hemodynamic characteristics often manifest as a rapid influx and efflux enhancement pattern, along with contrast agent elimination during the venous phase (Macari & Bosniak, 1999). The examination of these enhancement features served as the foundation for the clinical diagnosis in the current case.

IHC assay reveals that ductal cells predominantly exhibit positive staining for EMA, CK7, CEA, and CD117, while myoepithelial cells primarily exhibit positive staining for P63, SMA, Calponin, S-100, and CK5/6. These IHC markers serve as valuable tools for distinguishing between two distinct tumor cell differentiations, providing essential insights for the diagnosing and differential diagnosing of ACC.

Although progression-free survival of PACC patients treated with chemotherapy alone typically ranges from only 4 to 6 months (Ferrarotto et al., 2017; He & Chen, 2017; Huo et al., 2014), chemotherapy remains a primary treatment approach for advanced PACC patients. The platinum-containing dual-drug regimen recommended by the NSCLC guidelines, which includes carboplatin, cisplatin combined with pemetrexed, paclitaxel, and gemcitabine, is the mainstay chemotherapy regimen for PACC (Zhao et al., 2022). PACC patients often exhibit low or absent expression of PD-L1 (Wang et al., 2020), suggesting that immune checkpoint inhibitors alone might not be a beneficial treatment for PACC. There is an urgent need for alternative effective treatments.

There are still some constraints to this case report. The patient’s follow-up time is only a few months, and lifelong follow-up should be recommended.

Conclusion

The uniqueness of this case relies on the uncommon occurrence of renal metastasis from ACC, particularly originating from the lung, and the intricate nature of its diagnosis and treatment. Due to the high propensity for invasion and metastasis exhibited by adenoid cystic carcinoma, lifelong follow-up is recommended.