Case Report Primary Clear Cell Microcystic Adenoma of the Sinonasal Cavity: Pathological or Fortuitous Association? Rosalin Cooper, 1 Hannah Markham, 1 Jeffery Theaker, 1 Adrian Bateman, 1 David Bunyan, 2 Matthew Sommerlad, 1 Gillian Crawford, 3,4 and Diana Eccles 3,4 1 Department of Cellular Pathology, University Hospital Southampton NHS Foundation Trust, Southampton, UK 2 Wessex Regional Genetics Laboratory, Salisbury NHS Foundation Trust, Salisbury, UK 3 University of Southampton, Southampton, UK 4 Wessex Clinical Genetics Service, University Hospitals Southampton NHS Foundation Trust, Southampton, UK Correspondence should be addressed to Rosalin Cooper; rosalinanisha.cooper@uhs.nhs.uk Received 13 August 2016; Revised 14 December 2016; Accepted 15 January 2017; Published 5 February 2017 Academic Editor: Adriana Handra-Luca Copyright © 2017 Rosalin Cooper et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Primary clear cell microcystic adenoma of the sinonasal cavity is rare. It has previously been described only as a VHL-associated tumour. Von Hippel-Lindau (VHL) syndrome is an inherited cancer syndrome characterised by an elevated risk of neoplasia including clear cell renal cell carcinoma (ccRCC), haemangioblastoma, and phaeochromocytoma. We describe the second reported case of a primary clear cell microcystic adenoma of the sinonasal cavity. Te 39-year-old patient with VHL syndrome had previously undergone resection and ablation of ccRCC. He presented with epistaxis. Imaging demonstrated a mass in the ethmoid sinus. Initial clinical suspicion was of metastatic ccRCC. However, tumour morphology and immunoprofle were distinct from the previous ccRCC and supported a diagnosis of primary microcystic adenoma. Analysis of DNA extracted from sinonasal tumour tissue did not show loss of the wild-type allele at the VHL locus. Although this did not support tumour association with VHL disease, it was not possible to look for a loss-of-function mutation. Te association of primary microcystic adenoma of the sinonasal cavity with VHL disease remains speculative. Tese lesions are benign but are likely to require regular surveillance. Such tumours may require repeated surgical excision. 1. Introduction Von Hippel-Lindau (VHL) disease is a cancer syndrome characterised by an increased risk of multiple tumour types occurring across diferent organ systems. Tese include haemangioblastomas within the central nervous system and characteristic visceral lesions including clear cell renal cell carcinoma (ccRCC) and phaeochromocytoma [1]. Microcys- tic pancreatic lesions can also occur in the context of VHL disease [2]. Afected individuals carry germline mutations in the VHL tumour-suppressor gene with loss of the wild-type allele (normal gene copy) in a VHL disease-associated organ system leading to tumour formation [1, 3]. Sinonasal tumours are rare [4, 5]. Common benign lesions include inverted papillomas and osteomas [4], whilst common malignant lesions include squamous cell carcinoma and adenocarcinoma [5]. Tere has been only one reported case of a primary clear cell microcystic adenoma of the sinonasal cavity in the literature [6]. In this previously reported case, molecular analysis of tumour DNA confrmed tumour VHL disease association. Here we describe the sec- ond reported case of primary clear cell microcystic adenoma of the sinonasal cavity. 2. Case Report 2.1. Clinical History. A 39-year-old man with molecularly confrmed VHL disease presented with epistaxis in 2012. Molecular analysis had confrmed a germline VHL mutation in 2004. He had previously undergone excision of cerebellar haemangioblastoma in 2003. He had also undergone bilateral nephron sparing surgery for ccRCC (stage pT1a, Fuhrman grade up to 3) in 2005 and renal radiofrequency ablation in both 2008 and 2012. CT imaging demonstrated an ethmoid Hindawi Publishing Corporation Case Reports in Pathology Volume 2017, Article ID 9236780, 5 pages http://dx.doi.org/10.1155/2017/9236780