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Background In clinical practice, we often encounter patients with concurrent papillary thyroid carcinoma (PTC) and nodular goitre (NG). What are the similarities and differences between these patients and patients with simple NG? Whether NG-related nodules can affect the occurrence and development of PTC still remains unknown. Methods We retrospectively analysed 650 patients undergoing surgery for a thyroid nodule in our hospital from January 1, 2015, to January 31, 2016. A total of 574 patients who met the inclusion criteria were divided into the NG, PTC and NG&PTC groups according to their postoperative pathological features. SPSS 22 software was used to compare the characteristics of patients between the three groups, the similarities and differences of potential risk factors (such as age, sex, residence location, BMI…) and thyroid function between the NG&PTC and NG groups, and the similarities and differences of tumour pathological features between the NG&PTC and PTC groups. Results There were significant differences in the composition ratios of age, gender and residence location between the NG, PTC and NG&PTC groups. There were significant differences in residence location and body mass index (BMI) between the NG group and the NG&PTC group. There were significant differences in the number of cancer nodules, lymph node metastasis, and central lymph node metastasis between the NG&PTC and PTC groups. Conclusions Overweight may affect the occurrence of PTC in patients with NG. NG may limit the intra- or extra-glandular metastasis of PTC but does not affect the growth and invasion of PTC.

Polycyclic aromatic hydrocarbon (PAH) concentrations and fluxes were measured monthly in situ from rain events in an urban forest in the megapolitan city Guangzhou, China, to investigate impacts of forest canopy and soils on PAHs. Mean Σ9-PAH concentrations were 107.5, 101.6, 106.3, 107.1 and 42.4 ng L(-1) in precipitation, throughfall, seepage water at the 30 and 60 cm soil depth, and runoff, respectively, indicating a great decrease in the form of runoff. Meanwhile, annual fluxes of total PAHs decreased from precipitation (205.9 µg m(-2) year(-1)), to throughfall (156.3 µg m(-2) year(-1)), and to seepage water (65.3 µg m(-2) year(-1) at 30-cm soil depth and 7.5 µg m(-2) year(-1) at 60-cm soil depth), but increased in runoff (34.1 µg m(-2) year(-1)). When compared to precipitation, PAH fluxes decreased by 83.4% in runoff, with 29% contributed by forest canopy and 71% by soils. Soil biodegradation explained 18.2% of PAH reduction by the surface soil layer and 34.6% by the middle soil layer.

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