Hong Kong Med J Vol 16 No 4 # August 2010 # www.hkmj.org 307 Introduction The commonest presenting symptoms of nasopharyngeal carcinoma are an enlarged neck node or mass; nasal symptoms, such as unilateral nasal obstruction, blood-stained nasal secretions, or epistaxis; ear symptoms, such as unilateral hearing loss, tinnitus, and ear fullness; and blood-stained saliva. 1 Signs of nasopharyngeal carcinoma on endoscopy of the nasopharynx include an asymmetrical or eccentric mucosal covered fullness, ulceration, slough, blood and an obvious mass or tumour, which is usually exophytic, ulcerating or asymmetrical (Fig 1a and b). The diagnosis of nasopharyngeal carcinoma is made histopathologically on biopsy of nasopharyngeal tissue. The endoscopist samples nasopharyngeal tissue, usually with biopsy forceps, to determine the pathology of any lesion seen. Assessing the nasopharynx for abnormal lesions is subjective and requires experience. Changes may be subtle, and lesions may be in the submucosa of an otherwise normally appearing nasopharynx. Narrow-band imaging uses light in which the bandwidth has been narrowed, to illuminate the mucosa. The wavelength is shorter than standard white light. This shorter wavelength light is strongly absorbed by haemoglobin, which has an absorption peak of 415 nm, leading to a high contrast of blood vessels to surrounding non-vascular mucosal tissue. 2 Narrow-band imaging thus allows the endoscopist to assess the architecture of epithelial capillaries. This has proved useful in the detection of early oesophageal cancer, in which mucosal dysplasia is associated with changes in epithelial vessels. 3 Angiogenesis is essential for the transition of a premalignant to a malignant lesion, and so this ability to detect morphological changes in the microvessels of the mucosa has great potential benefit. 4 Normal nasopharyngeal mucosa contains various amounts of lymphoid tissue (Fig 1c). Large amounts of lymphoid tissue in children and adolescents are known as adenoids, while nasopharyngeal lymphoid tissue may be minimal or absent in adults. Mucosal lymphoid tissue in adults has a regular follicular pattern on narrow-band imaging, in which pale follicles have a thin, dark border (Figs 1d and 2a). The ratio of the pale follicle to the dark border (pale-to-dark ratio) is roughly 90%. The authors have noticed that this ratio is reversed in some patients undergoing routine nasopharyngeal endoscopy, with each ‘follicle’ consisting of a dark centre, surrounded by a pale border. The pale-to-dark ratio is in the order of 50%. This apparent reversal of the narrow-band imaging characteristics of nasopharyngeal mucosa appears similar to the abnormal capillary loop pattern seen on narrow-band imaging of early oesophageal cancer. 5 In the oesophagus, the increased microvascular density in the mucosa indicates dysplasia or malignancy, and is therefore an indication for biopsy. An illustrative case is presented of a patient who had features of an abnormal capillary pattern on endoscopic narrow-band imaging of the nasopharynx, adjacent to a biopsy-proven carcinoma. Reversal of pale-to-dark nasopharyngeal follicle ratio on narrow-band imaging C A S E R E P O R T Key words Biopsy; Carcinoma; Diagnostic imaging; Endoscopy; Nasopharynx Hong Kong Med J 2010;16:307-9 The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong: Department of Otorhinolaryngology, Head and Neck Surgery AC Vlantis, FCS(SA)ORL HS Chan, FRCSEd JKS Woo, FRCSEd MCF Tong, FRCSEd(ORL) CA van Hasselt, MMed(Otol) Department of Anatomical and Cellular Pathology ABW Chan, FHKCPath Correspondence to: Dr AC Vlantis Email: lexvlantis@cuhk.edu.hk Alexander C Vlantis Amy BW Chan HS Chan John KS Woo Michael CF Tong C Andrew van Hasselt 屈力行 陳碧雲 陳慶生 吳港生 唐志輝 尹懷信 Normal nasopharyngeal mucosa contains varying amounts of lymphoid tissue, which in adults may be minimal or absent. Nasopharyngeal mucosa with minimal lymphoid tissue has a regular follicular pattern on narrow-band imaging; pale follicles have thin, dark borders and the ratio of the pale follicle to the dark border (pale-to-dark ratio) is roughly 90%. In some patients undergoing routine nasopharyngeal endoscopy, the pale-to-dark ratio is reversed on narrow-band imaging, with dark centres surrounded by pale borders and a pale-to-dark ratio of roughly 50%. These dark follicles may represent abnormal capillary loops, as they have the same appearance as microvascular changes seen on narrow-band imaging of the oesophageal mucosa which indicate dysplasia or malignancy. While this observed change in the follicular pattern may be an early event in the evolution of nasopharyngeal carcinoma, the significance of this finding remains to be confirmed by a larger-scale study.