Value of 18F-FDG PET/CT examination in the differential diagnosis of primary nasopharyngeal lymphoma and nasopharyngeal carcinoma

Abstract

Objective To explore the value of 18F-FDG PET/CT examination in the differential di-agnosis of primary nasopharyngeal lymphoma (PNL) and nasopharyngeal carcinoma (NPC). Methods PET/CT data of 33 patients with PNL and 71 patients with NPC who were confirmed histopathologically and had not undergone oncotherapy before examination were retrospectively analyzed. The form, range, in- vasion, volume, SUVmax of nasopharyngeal lesion, and lymphadenopathy involvement were analyzed com-paratively. The SUVmax and volume of lesions that confirmed diffuse large B cell lymphoma(DLBCL) were compared with NPC. t-text and χ2-text with SPSS 13.0. Results Diffuse infiltration of all nasopharyn-geal walls was detected in 20 of 33 patients with PNL(bilateral symmetry in 14 patients and asymmetry in 6) and 10 of 71 patients with NPC(bilateral symmetry in 4 patients and asymmetry in 6). Partial infiltra-tion of nasopharyngeal walls was observed in 13 of 33 patients with PNL(unilateral invasion in 7 patients and bilateral invasion in 6) and 61 of 71 patients with NPC(unilateral invasion in 39 patients and bilat-eral invasion in 22). Statistical significances were found between diffuse and partial infiltration, unilateral and bilateral invasion, and symmetry and asymmetry of nasopharyngeal walls of PNL and NPC(χ2=23.75, 10.38, and 16.74, respectively; all P 0.05). The SUVmax's of PNL and NPC were 12.00±6.34, 14.26±6.42, and 10.09±4.41, respectively. No significant difference was found between the SUVmax's of PNL and NPC(t=1.55; P>0.05). Significant difference was found between DL-BCL and NPC(t=2.67; P 0.05). Through CT imaging, lymphatic ne-crosis was detected in 3 of 26 patients with lymphatic involvement of PNL and 31 of 51 patients with lym-phatic metastasis of NPC. Significant difference was found between the two groups(χ2=16.94; P 0.05). Conclusions PET/CT examination has a definite diagnosis value in patients with PNL and NPC. The differential diagnosis between PNL and NPC was mainly according to form, range, and invasion of nasopharyngeal lesion. The metabolic level of differ-ent pathological subtypes may be higher or lower than that of NPC. The metabolic activity of DLBCL was higher than that of NPC. The volume of nasopharyngeal lesion cannot be considered as a main basis to dis-tinguish between PNL and NPC. Key words: Nasopharyngeal neoplasms; Fluorodeoxyglucose F18; Positron-emission tomography; Tomography, X-ray computed; Nasopharyngeal lymphoma