Dear Editor,

I read with interest the original article entitled “Indeterminate pulmonary subsolid nodules in patients with no history of cancer: growing prediction, CT pattern, and pathological diagnosis” by Guo et al.¹ In this retrospective study, the authors assessed the growth patterns of indeterminate subsolid pulmonary nodules on computed tomography in patients without a history of malignancy. The authors reported that the risk of pulmonary subsolid nodule growth increases by 4% each year in patients without a history of malignancy. They further stated that partial solid nodules have a three-fold greater risk of growth than non-solid nodules, and that subsolid nodules with aggressive pathological features grow faster. Although these results are remarkable and make an essential contribution to the literature, I suggest a few points need to be clarified to ensure the reproducibility of this study and the reliability of the data.

First, the authors reported that 80 subsolid nodules in 77 patients were resected. However, they have specified only 77 pathological diagnoses, including 29 adenocarcinomas in situ, 29 minimally invasive adenocarcinomas, 18 invasive adenocarcinomas, and one atypical adenomatous hyperplasia.¹ There is a discrepancy in the number of resected and histopathologically reported nodules in the study.

Second, Guo et al.¹ reported that all indeterminate subsolid nodules in their study were pre-malignant or had malignant histopathology. However, according to the literature, the incidence of malignancy in subsolid lung nodules is much lower than in the study of Guo et al.¹ It is known that the presence and size of the solid component and the size of the subsolid nodule increase the risk of malignancy. The malignancy rate of non-solid nodules smaller than 1 cm is approximately 1%, whereas the malignancy rate of partial solid nodules with a solid component of ≥6 mm is around 20%.^2,3,4 The frequency of malignancy in indeterminate subsolid lung nodules in the current study is inconsistent with that reported in the literature.