CASE REPORT Sinonasal renal cell-like adenocarcinoma: Easily misdiagnosed sinonasal tumor Ching-Nung Wu MD 1 | I-Chieh Chuang MD 2 | Ming-Jung Chuang MD 3 | Wei-Chih Chen MD 1 1 Department of Otolaryngology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan 2 Department of Anatomic Pathology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan 3 Department of Neurosurgery, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan Correspondence Wei-Chih Chen, Department of Otolaryn- gology, Kaohsiung Chang Gung Memo- rial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan. Email: jarva@adm.cgmh.org.tw Abstract Background: Sinonasal renal cell-like adenocarcinoma is rare and exhibits unique pathological and clinical manifestations. Correct diagnosis and treatment of this newly described entity are challenging for both clinicians and pathologists. Methods: We report a female patient with sinonasal renal cell-like adenocarcinoma who initially presented with right intermittent epistaxis. Results: A 26-year-old woman presented with a 1-year history of right intermittent epistaxis and hyposmia. Nasal endoscopy revealed a reddish tumor in the right nasal cavity. An MRI revealed a hyperintense tumor arising from the right olfactory cleft accompanied by prominent feeding vessels originating from the anterior ethmoid artery (AEA). We performed a bicoronal incision with ligation of the AEA followed by endo- scopic resection of the skull base tumor. The patient is currently free of recurrence. Conclusion: This is the first study to review the clinical features of sinonasal renal cell-like adenocarcinoma. We recommend surgical resection as the mainstay of treatment. KEYWORDS clear cell carcinoma, low-grade adenocarcinoma, outcome, sinonasal malignant tumor, treatment 1 | INTRODUCTION Sinonasal renal cell-like adenocarcinoma is an extremely rare sinonasal malignant neoplasm. This tumor was first described by Moh’d Hadi et al 1 and Zur et al 2 in 2002, who noted the resemblance of its cell morphology to that of the clear-cell type of renal cell carcinoma (RCC) but with no evidence of a preex- isting, synchronous, or subsequent RCC after a detailed survey. In 2008, 2 more cases were reported by Storck et al. 3 Later, Brandwein-Gensler and Wei 4 identified another possible 10 patients in the published literature, although the degree of detail regarding those cases varies. In 2015, Shen et al 5 added 2 more patients with sinonasal renal cell-like adenocarcinoma based on a pathological review. Thus, currently, only 15 possible cases have been reported in the English medical literature. In previous reports, the pathologic features of sino- nasal renal cell-like adenocarcinoma were thoroughly dis- cussed. However, the clinical features of the tumor have yet to be adequately determined. Moreover, given the rar- ity of this tumor, its treatment is still controversial. A fur- ther difficulty is that most of the tumors were initially misdiagnosed, a problem that also gained our attention. Here, we report 1 case of sinonasal renal cell-like adeno- carcinoma and provide a clinical review of this extremely rare disease, including its clinical features, prognosis, and treatment. 2 | CASE REPORT A 26-year-old woman presented with a 1-year history of right intermittent epistaxis, progressive right nasal obstruction, and Jonathan Irish, MD, FRCSC, Section Editor Head & Neck. 2018;1–5. wileyonlinelibrary.com/journal/hed V C 2018 Wiley Periodicals, Inc. | 1 Received: 6 November 2017 | Revised: 16 February 2018 | Accepted: 7 May 2018 DOI: 10.1002/hed.25338