Abstract
Background
Pulmonary sclerosing pneumocytoma (PSP) is a rare benign tumor with various manifestations, posing a challenge for accurate diagnosis and appropriate management. Imaging, particularly computed tomography (CT), is crucial for the diagnosis of PSP, and imaging surveillance is adopted as a strategy for the management of PSP patients. However, the natural history and growth patterns of PSP remain poorly characterized, creating an urgent need for evidence-based surveillance protocols to guide clinical management. This study aimed to investigate the CT manifestations and tumor growth patterns of PSP to enhance understanding and provide evidence for the clinical management of PSP patients.
Methods
A retrospective observational cohort study was conducted among PSP patients diagnosed between August 2014 and August 2025 at a single tertiary hospital in southwestern China. Inclusion criteria were: (I) histopathologically diagnosed PSP registered in the pathology information system; (II) available preoperative chest CT; and (III) complete clinical records. Exclusion criteria included: (I) incorrect diagnosis of PSP; (II) incomplete CT data or CT of poor quality; and (III) prior lung surgery or malignancy affecting follow-up assessment. Baseline clinical factors (age, sex, symptoms, smoking history) and CT features (size, location, morphology, calcification, enhancement patterns) were systematically recorded. For 17 patients with serial CT scans, tumor volume doubling time (TVDT) was calculated using the modified Schwartz formula. Growth patterns were classified as stable or no growth [volume doubling time (VDT) >6,000 days], slow or indolent (600–6,000 days), and rapid (<600 days) according to the TVDT. The predefined primary outcome was tumor growth kinetics; secondary outcomes included CT characteristics and postoperative recurrence.
Results
The cohort was predominantly female, with a mean age of 48.4±12.5 years at the time of diagnosis. Most patients were asymptomatic. All of the PSP lesions manifested as solitary, well-circumscribed nodules or masses, predominantly in the lower lobes. The top three most common CT features observed in PSP included oval shape, calcification, and significant enhancement after contrast administration. Twenty-five out of 68 patients were correctly diagnosed as PSP preoperatively. Among 17 cases with serial CT, 5 (29.4%) showed no growth, 6 (35.3%) showed slow growth, and 6 (35.3%) showed rapid growth. All patients underwent surgical resection with no recurrence or metastasis observed.
Conclusions
This study indicates that PSP might have characteristic features, and radiological features may suggest the diagnosis of PSP. PSP exhibits heterogeneous growth patterns ranging from no growth to slow-growing and rapid-growing rates. These findings suggest that individualized surveillance intervals should be adopted for PSP-suspicious nodules: while some PSP cases with no growth or slow-growing rates may permit extended follow-up, cases with rapid growth warrant shorter follow-up intervals. This evidence supports tailored clinical management for PSP patients.
Keywords: Pulmonary sclerosing pneumocytoma (PSP), computed tomography (CT), tumor growth rate (TGR), tumor volume doubling time (TVDT), retrospective cohort study
Highlight box.
Key findings
• This study included 68 pulmonary sclerosing pneumocytoma (PSP) patients, predominantly asymptomatic females. Computed tomography (CT) mostly showed solitary nodules with smooth margins, commonly with calcification and obvious enhancement. Analysis of 17 cases with serial CT scans revealed significant heterogeneity in PSP growth patterns: 5 stable, 6 slow-growing, and 6 rapidly growing.
What is known and what is new?
• PSP has traditionally been regarded as a benign, slow-growing tumor; preoperative diagnosis remains challenging, and little is known about the tumor growth rate of PSP.
• This study systematically reveals CT features and the growth patterns of PSP, and heterogeneous growth patterns—with some lesions demonstrating stable or slow growth and others exhibiting rapid growth with volume doubling times of less than 600 days—challenge the traditional perception of PSP as a uniformly indolent lesion.
What is the implication, and what should change now?
• Individualized management strategies should be adopted for PSP: imaging surveillance may be considered for stable or slow-growing lesions, while shorter follow-up intervals and active intervention are needed for rapidly growing cases. Enhanced awareness of PSP imaging features is needed to improve preoperative diagnostic accuracy.
Introduction
Pulmonary sclerosing pneumocytoma (PSP) is a benign tumor with malignant potential, classified as a type of adenoma according to the World Health Organization classification (1,2). The diagnosis of PSP remains challenging due to its rarity, histological heterogeneity, and diverse clinical presentations (3,4). Although pathology remains the gold standard in diagnosing PSP, the invasive nature of obtaining specimens limits its early and widespread application. Additionally, intraoperative frozen section has a high misdiagnosis rate of 10–55.9% for diagnosing PSP (5,6), contributing to clinical uncertainty. This diagnostic uncertainty has profound clinical implications, often leading to either unnecessary overtreatment (e.g., lobectomy for a benign lesion) or inadequate surveillance (5).
Clinically, PSP typically presents as a well-circumscribed peripheral pulmonary nodule, frequently detected incidentally on imaging performed for physical examinations or unrelated reasons (7,8). Despite its generally benign nature, PSP has the potential for local invasion (9), and rare instances of metastasis have been documented (10,11). This potential, though rare, creates a significant clinical dilemma regarding whether patients should undergo active surveillance or surgical resection. Distinguishing PSP from other pulmonary malignancies, particularly adenocarcinoma, is therefore clinically crucial given the stark differences in therapeutic strategies and prognostic outcomes (5). However, this distinction remains challenging as PSP may mimic common lung cancers both clinically and radiologically (12,13).
While some imaging features, especially those based on computed tomography (CT), have been reported in the literature (7,14), the preoperative diagnosis of PSP in real-world practice requires further investigation. More importantly, understanding tumor growth kinetics is essential for differential diagnosis between benign tumors and aggressive malignancies, as the growth features might reflect the biological nature of the tumor (15). However, the natural history and growth pattern of PSP remain poorly characterized, resulting in a critical knowledge gap regarding imaging surveillance strategies for PSP. The existing literature on this topic consists primarily of case reports or small series with limited follow-up data (16). Some recent case reports have suggested that PSP may exhibit rapid growth rates with a volume doubling time (VDT) of 426 days (17), contradicting its traditional perception as a slow-growing (18) or indolent lesion (19,20). This inconsistency represents another knowledge gap regarding the appropriate management of pulmonary nodules, for which active imaging surveillance might play an important role.
Given the rarity of PSP and the scarcity of systematic data regarding its growth kinetics, this retrospective cohort study aims to investigate the clinical and radiological manifestations and growth patterns of PSP. By systematically analyzing this real-world cohort, we seek to investigate the imaging features and the tumor growth patterns of PSP based on CT imaging to enhance understanding of this entity and provide evidence-based insights for clinical management, especially imaging surveillance, of PSP patients. We present this article in accordance with the STROBE reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-0786/rc).
Methods
Study design and patient selection
A retrospective cohort study was conducted at The Affiliated Hospital of Guizhou Medical University to identify patients diagnosed with PSP between August 2014 and August 2025. We did not perform estimation of sample size, as this was an observational study, and we collected all the patients during this period. The eligibility criteria for patient inclusion, which are shown in Figure 1, were as follows:
Figure 1.
Flow chart of the present study. CT, computed tomography; PSP, pulmonary sclerosing pneumocytoma.
Histopathologically confirmed PSP registered in the pathology information system;
Available preoperative chest CT images;
Complete clinical records.
Exclusion criteria included:
Patients with an incorrect diagnosis on frozen biopsy;
Incomplete CT data or CT of poor quality;
Prior lung surgery or malignancy affecting follow-up assessment.
The pathology diagnosis was retrospectively validated by two pathologists (Y.W. and Y.Y., both with diagnostic experience in pathology for more than 8 years) based on a combination of gross examination, frozen tissue, and the immunohistochemical staining findings. Key diagnostic evidence included findings of surface cuboidal cells and round polygonal stromal cells organized in at least two of the four typical architectural patterns—papillary, sclerotic, solid, and hemorrhagic—characteristic of PSP.
Data collection
A review of electronic medical records in the hospital information system of The Affiliated Hospital of Guizhou Medical University was performed to collect demographic information, clinical information (age, sex, symptoms, smoking history), CT features (size, location, morphology, calcification, enhancement patterns), and treatment details. Data extraction was performed by two investigators (L.T. and X.Z.) and cross-verified for accuracy.
Imaging acquisition and analysis
Non-contrast CT scans of the patients in this cohort were acquired on several multi-slice spiral CT scanners with more than 32 detector rows in our hospital during breath-hold, with the scan range covering the lung apex to the lung base. Contrast-enhanced scans were performed on a 128-slice spiral CT scanner (Somatom Definition AS, Siemens Healthineers, Forchheim, Germany). Images for the arterial and venous phases were acquired at 30 and 60 seconds after contrast administration, respectively. The chest CT scan parameters were as follows: tube voltage 100–120 kV, automatic tube current modulation (reference mAs, approximately 100), field of view (FOV) 350 mm, matrix of 512×512. Images were reconstructed using both standard and high-resolution algorithms, with reconstruction slice thicknesses and intervals of 5 and 1 mm, respectively, and measurements were taken using lung window settings.
Chest CT scans of the patients were retrospectively reviewed by two experienced radiologists (H.X. and X.G., both with more than 10 years of thoracic diagnostic experience) who were blinded to the clinical outcomes and pathological results. The longest dimension of the tumor in the axial plane and the orthogonal dimensions were recorded. For cases with two or more CT scans, the initial CT was adopted to record its clinical and radiological features, and the initial CT and the last CT were used to calculate their volume, tumor growth rate, and VDT. Tumor volume was calculated using the ellipsoid formula: . When possible, at least two sequential scans were identified to calculate the VDT using the formula: (21), where t1 and t2 are the times of the scans, and V1 and V2 are the tumor volumes at these times.
All patients were instructed to undergo follow-up at 3 months, 6 months, 1 year, and annually thereafter, with non-contrast-enhanced chest CT scans performed at our hospital during each visit. Most patients adhered to the regular follow-up schedule. All follow-up chest CT scans of the patients were interpreted by two certified radiologists. Those who did not follow up regularly were contacted by phone and advised to undergo chest CT scans at local hospitals, and their recurrence and disease progression were tracked by telephone follow-up.
Quality assurance
To ensure the accuracy of the data, a quality assurance program was implemented, which included double data entry, range checks, and regular audits of the data collection process.
Statistical analysis
Descriptive statistics were used to summarize patient demographics and tumor characteristics. Continuous variables were expressed as mean ± standard deviation (SD), and categorical variables were presented as frequencies and percentages. The VDT was calculated for each patient and summarized as mean ± SD. The analysis was performed with the statistical software package Free software version 2.1 based on R-3 (http://www.R-project.org; The R Foundation).
Ethical considerations
This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. This study was approved by the Institutional Review Board of The Affiliated Hospital of Guizhou Medical University (Nos. 2022-734 and 2023-288), and the requirement for informed consent was waived due to its retrospective nature.
Results
Patient characteristics and clinical presentation
This study included 68 patients with pathologically confirmed PSP, and the detailed information of this cohort is shown in Table 1. The cohort was predominantly female (95.6%, 65/68), with a mean age of 48.4±12.5 years at the time of diagnosis. The majority of patients were non-smokers (98.5%, 67/68) and non-drinkers (92.6%, 63/68). Most patients were asymptomatic at diagnosis (75.0%, 51/68), with 25.0% (17/68) presenting with symptoms. The mean body mass index was 23.7±3.2 kg/m2.
Table 1. Baseline characteristics of the study population.
| Variables | Total (n=68) | Subgroup 1 (n=51) | Subgroup 2 (n=17) |
|---|---|---|---|
| Gender | |||
| Female | 65 (95.6) | 49 (96.1) | 16 (94.1) |
| Male | 3 (4.4) | 2 (3.9) | 1 (5.9) |
| Symptoms | |||
| No | 51 (75.0) | 35 (68.6) | 16 (94.1) |
| Yes | 17 (25.0) | 16 (31.4) | 1 (5.9) |
| Height (cm) | 158.0±5.7 | 157.6±5.9 | 159.3±5.3 |
| Weight (kg) | 59.1±9.1 | 59.0±8.7 | 59.5±10.4 |
| BMI (kg/m2) | 23.7±3.2 | 23.7±3.1 | 23.4±3.6 |
| Smoking | |||
| No | 67 (98.5) | 50 (98.0) | 17 (100.0) |
| Yes | 1 (1.5) | 1 (2.0) | 0 (0.0) |
| Drinking | |||
| No | 63 (92.6) | 48 (94.1) | 15 (88.2) |
| Yes | 5 (7.4) | 3 (5.9) | 2 (11.8) |
| Diameter (mm) | 23.6±11.8 | 24.9±12.2 | 19.9±9.8 |
| Volume (mm3) | 11,050.0±19,156.8 | 12,726.7±21,398.6 | 6,019.7±8,364.5 |
| CT value (HU) | 5.0±127.1 | 35.4±17.1 | −49.7±204.5 |
| Arterial CT value (HU) | 59.6±84.6 | 73.1±30.0 | 24.4±152.0 |
| Venous CT value (HU) | 64.3±84.8 | 77.3±25.6 | 30.2±155.0 |
| Lobe | |||
| RUL | 10 (14.7) | 6 (11.8) | 4 (23.5) |
| RML | 10 (14.7) | 7 (13.7) | 3 (17.6) |
| RLL | 24 (35.3) | 19 (37.3) | 5 (29.4) |
| LUL | 7 (10.3) | 6 (11.8) | 1 (5.9) |
| LLL | 17 (25.0) | 13 (25.5) | 4 (23.5) |
| Shape | |||
| Oval | 62 (91.2) | 47 (92.2) | 15 (88.2) |
| Round | 3 (4.4) | 2 (3.9) | 1 (5.9) |
| Irregular | 3 (4.4) | 2 (3.9) | 1 (5.9) |
| Intratumoral calcification | |||
| No | 51 (75.0) | 38 (74.5) | 13 (76.5) |
| Yes | 17 (25.0) | 13 (25.5) | 4 (23.5) |
| Overlying vessel sign | |||
| No | 49 (72.1) | 38 (74.5) | 11 (64.7) |
| Yes | 19 (27.9) | 13 (25.5) | 6 (35.3) |
| Halo sign | |||
| No | 61 (89.7) | 48 (94.1) | 13 (76.5) |
| Yes | 7 (10.3) | 3 (5.9) | 4 (23.5) |
| Spiculation | |||
| No | 64 (94.1) | 47 (92.2) | 17 (100.0) |
| Yes | 4 (5.9) | 4 (7.8) | 0 (0.0) |
| Lobulation | |||
| No | 60 (88.2) | 43 (84.3) | 17 (100.0) |
| Yes | 8 (11.8) | 8 (15.7) | 0 (0.0) |
| Growth across pleural | |||
| No | 64 (94.1) | 47 (92.2) | 17 (100.0) |
| Yes | 4 (5.9) | 4 (7.8) | 0 (0.0) |
| Air crescent sign | |||
| No | 64 (94.1) | 47 (92.2) | 17 (100.0) |
| Yes | 4 (5.9) | 4 (7.8) | 0 (0.0) |
| Preoperative diagnosis | |||
| Benign | 65 (95.6) | 49 (96.1) | 16 (94.1) |
| Malignant | 3 ( 4.4) | 2 (3.9) | 1 (5.9) |
| Radiological diagnosis | |||
| PSP | 25 (36.8) | 18 (35.3) | 7 (41.2) |
| Solitary nodules | 12 (17.6) | 7 (13.7) | 5 (29.4) |
| Benign tumor | 23 (33.8) | 19 (37.3) | 4 (23.5) |
| Tuberculosis | 2 (2.9) | 2 (3.9) | 0 (0.0) |
| Hamartoma | 3 (4.4) | 3 (5.9) | 0 (0.0) |
| Lung cancer | 3 (4.4) | 2 (3.9) | 1 (5.9) |
| Operation method | |||
| Wedge resection | 58 (85.3) | 43 (84.3) | 15 (88.2) |
| Lobectomy | 10 (14.7) | 8 (15.7) | 2 (11.8) |
| Complications | |||
| No | 48 (70.6) | 36 (70.6) | 12 (70.6) |
| Yes | 20 (29.4) | 15 (29.4) | 5 (29.4) |
Data are presented as n (%) or mean ± SD. Subgroup 1: exclude patients without follow-up CT (n=45) and follow-up CT interval <4 weeks (n=6). Subgroup 2: patients with serial CT to calculate tumor growth rate (n=17). For more details, see Figure 1. BMI, body mass index; CT, computed tomography; HU, Hounsfield units; LLL, left lower lobe; LUL, left upper lobe; PSP, pulmonary sclerosing pneumocytoma; RLL, right lower lobe; RML, right middle lobe; RUL, right upper lobe; SD, standard deviation.
CT imaging characteristics and preoperative diagnostic performance
A total of 68 patients with eligible CT data (including 17 cases with two serial CT scans) were reviewed. PSP lesions were most commonly located in the right lower lobe (35.3%, 24/68), followed by the left lower lobe (25.0%, 17/68), right upper lobe (14.7%, 10/68), right middle lobe (14.7%, 10/68), and left upper lobe (10.3%, 7/68). The mean tumor length was 23.6±11.8 mm and mean volume of 11,050.0±19,156.8 mm3.
The majority of lesions presented as oval nodules or masses (91.2%, 62/68), as shown in Figure 2. The mean CT attenuation values were 5.0±127.1 Hounsfield units (HU) on non-contrast imaging, 59.6±84.6 HU in the arterial phase, and 64.3±84.8 HU in the venous phase. As for radiological signs reported previously in other literature (22), the lobulation sign was observed in 11.8% (8/68) of cases. A halo sign was present in 10.3% (7/68) of lesions. Intratumoral calcification was identified in 25.0% (17/68) of cases. The air crescent sign was seen in only 5.9% (4/68) of lesions. Growth across the pleura was observed in 5.9% (4/68) of cases (as shown in Figure 2D). Besides, a minority of the lesions exhibited irregular (4.4%, 3/68) or lobulated shapes (4.4%, 3/68), which were more commonly reported in malignant tumors, such as pulmonary carcinomas.
Figure 2.
Typical images of the PSP cases included. (A,B) A 63-year-old woman with a right lower lobe lesion detected on physical examination 10 days ago. (A) An oval soft-tissue nodule (blue arrow) could be observed in the medial basal segment of the right lower lobe. (B) Contrast-enhanced CT revealed a nodule with homogenous enhancement, with adjacent vessel contact (red arrow) and intratumoral vascular penetration. (C,D) A 63-year-old woman with a left lung mass detected on physical examination 1 week ago. (C) A patchy soft-tissue density lesion (blue arrow) was noted in the left lower lobe near the mediastinal pleura, demonstrating homogeneous enhancement. (D) Trans-fissure growth across the oblique fissure (red arrow) could be observed on coronal reconstruction images. (E) A 51-year-old woman referred for evaluation of a left lower lobe mass detected at a local hospital. Contrast-enhanced CT showed an oval nodule in the left lower lobe (blue arrow) with intralesional calcifications (red arrow). (F) A 47-year-old woman with intermittent chest pain for more than 4 years. A nodule was detected in the left lower lobe near the oblique fissure (blue arrow), surrounded by a halo sign (red arrow) and air crescent sign (yellow arrow). CT, computed tomography; PSP, pulmonary sclerosing pneumocytoma.
In terms of the performance of preoperative diagnosis on CT, 65 cases were correctly diagnosed as benign based on preoperative CT, and 3 cases were misdiagnosed as lung cancer. Of all the cases, 25 cases were diagnosed as PSP based on preoperative CT, 35 cases were reported as benign lesions without a specific pathological diagnosis, 3 cases were considered as hamartomas, and 2 cases were preoperatively considered as tuberculomas, as shown in Table 1.
Growth patterns
Seventeen cases were finally included to investigate the growth kinetics, and tumor growth patterns were described using tumor VDT (TVDT) and tumor growth rate (TGR). TVDT and TGR were calculated based on volumes measured on serial CT scans (as shown in Figure 3). The TVDT and distribution of each lesion were displayed in the left panel of Figure 4. To better distinguish the growth differences between patients, we used 600 and 6,000 days as cut-off values to further stratify the enrolled patients into three groups, and the right panel of Figure 4 shows the results of our grouping. Five of the tumors demonstrated no growth during the follow-up period, and we defined this group (group 3) as stable lesions, indicating that the PSP lesion showed no growth and its TVDT was longer than 6,000 days, which was shown in Figure 4 as 10,000+ days. Six of the lesions demonstrated with TVDT ranging between 600 and 6,000 days, and we defined it as an indolent or slow-growing lesion, which was shown as group 2 in Figure 4. The remaining six cases of PSP exhibited with more rapid growth, with TVDT shorter than 600 days, and we defined this as the rapid growth group, which was shown as group 1 in Figure 4.
Figure 3.
Cases demonstrated with different TGRs. Case (A,B): a 43-year-old woman with a right lower lobe pulmonary nodule with no growth. (A) Chest CT on February 13, 2024, showed a solid nodule (11 mm × 10 mm) in the medial basal segment of the right lower lobe. (B) Follow-up chest CT on September 19, 2024, demonstrated no significant change in the right lower lobe nodule. Case (C,D): a 54-year-old woman with a slow-growing nodule. The patient presented with right-sided back pain for 15 days. (C) Chest CT on July 22, 2021, revealed a rounded nodule (9 mm × 8 mm) in the posterior basal segment of the right lower lobe. (D) Follow-up chest CT on July 3, 2025, showed growth of the nodule in the posterior basal segment of the right lower lobe, now measuring 13 mm × 11 mm with well-defined margins. Case (E,F): a 59-year-old woman with a rapid-growing nodule. The patient presented with cough and sputum production for more than 10 days. (E) Chest CT on January 25, 2024, demonstrated a nodule (16 mm × 13 mm) in the medial basal segment of the left lower lobe. (F) Follow-up chest CT on March 14, 2024, revealed enlargement of the nodule in the medial basal segment of the left lower lobe, now measuring 17 mm × 15 mm. CT, computed tomography; TGR, tumor growth rate.
Figure 4.
TVDT of patients investigated and subgroups. The bar chart on the left shows the TVDT in days for 17 enrolled patients, among whom 5 patients showed no observed tumor growth and were described as 10,000+. The right figure presents the grouping based on growth rate and TVDT, using 600 and 6,000 days and their corresponding TGR values as the cutoff thresholds for stratification. Group 1: rapid-growth lesion; PSP exhibited with more rapid growth, with TVDT shorter than 600 days. Group 2: indolent or slow-growing lesion; TVDT ranging between 600 and 6,000 days. Group 3: stable lesion; PSP lesion showed no growth, and its TVDT was longer than 6,000 days. PSP, pulmonary sclerosing pneumocytoma; TGR, tumor growth rate; TVDT, tumor volume doubling time.
Treatment and follow-up
Surgical resection was performed in all patients. The majority of patients (58/68) underwent wedge resection, while a minority (10/68) underwent lobectomy. Postoperative complications included minor pneumothorax, hydropneumothorax, and subcutaneous emphysema. No other complications—such as postoperative hemorrhage, bronchopleural fistula, or empyema—were observed. The median follow-up duration after surgery was 21 months (range, 3 to 120 months). No local recurrences or distant metastases were observed during the follow-up period.
Discussion
The current study provides an observational study of the clinical, CT features, and tumor growth patterns of pulmonary PSP based on a real-world cohort in a single hospital for over 10 years. In this cohort, most PSPs were detected through physical examinations or incidental findings for other purposes. All of the lesions presented as solitary nodules or masses in the lung, with a female predominance. On CT scans, most PSPs present as a solid lesion with smooth margins, and calcification is a relatively common finding on non-contrast CT scans in this cohort. Following contrast-enhanced CT, most tumors demonstrated intense enhancement, which could be either homogeneous or heterogeneous. On serial CT, PSP demonstrated heterogeneous growth patterns.
PSP might have some characteristic clinical features, and it might be possible to suggest the diagnosis of PSP operatively. In this cohort, a significant gender predominance, with only 3 male patients and the remainder being female, was observed, resulting in a male-to-female ratio of over 1:20, which was higher than others previously reported in the literature (5,23). Regarding clinical detection methods and manifestations, the majority (75%, 51/68) of patients were asymptomatic preoperatively. A possible reason for the high proportion of asymptomatic cases is the increasingly widespread availability of screening CT in recent years. In this study, 25 cases were diagnosed as PSP based on enhanced CT preoperatively, suggesting that preoperative imaging might have certain diagnostic value for typical PSP. 65 cases were preoperatively diagnosed as benign lesions, indicating that PSP had some characteristic features on CT. These findings underscore the necessity of strengthening research into distinguishing features between PSP and other lesions manifesting as pulmonary nodules.
PSP had some typical features on CT, and the diagnosis of PSP should be made cautiously based on radiological findings. All the lesions presented as solitary lesions with smooth boundaries in this cohort, and an oval shape was observed in 91.2% of the cases, which is in accordance with other studies regarding CT features reported for diagnosing PSP (7,22). Overlying vessel or adjacent vessel sign (27.9%) and intratumoral calcification (25%) were commonly observed. Lobulation, the halo sign, and air crescent were also identified (24,25) in this cohort. Following contrast administration, most lesions demonstrate obvious enhancement, which may be homogeneous or heterogeneous. These findings were consistent with previously reported imaging characteristics (7), indicating that radiologists could suggest the diagnosis of PSP for cases with typical imaging features. Although the incidence is low, the possibility of PSP should be considered in the differential diagnosis of pulmonary nodules (26). Unexpectedly, some of the PSP lesions exhibited lobulation and spiculation, suggesting that PSP might present with a variety of imaging features. Three cases were diagnosed as malignant tumors preoperatively. In addition to that, a higher probability of transpleural growth (as shown in Figure 2D) was observed in five of the lesions, indicating that more imaging features and experience with PSP were still needed.
PSP demonstrates heterogeneous growth rates, and this has several clinical implications for management of this rare tumor. Among the 17 cases investigated, five cases showed virtually no growth during the observation period, and six cases demonstrated with TVDT ranging between 600 and 6,000 days, suggesting that the majority of PSPs exhibit benign biological behavior with a stable condition or rather slow growth. This is in accordance with some reported in the literature (15,18,26), supporting the traditional belief about PSP as a benign tumor. At the same time, six cases in this cohort demonstrated rapid growth rates at a VDT ranging from 330 to 517 days, and this is consistent with several case reports published in recent years (17,19,27), in which the VDT of PSP ranges from 249 (19) to 426 days (17). Such rapid TGRs overlap with that of lung cancers (21), suggesting that the role of growth kinetics in differentiating between benign and malignant tumors might need more explorations. Our findings have significant clinical implications. On the one hand, the majority of the PSP lesions in our cohort had stable or indolent growth rates, suggesting that active surveillance may be a safe and appropriate management strategy for selected PSP patients, particularly considering the invasive nature of surgery and difficulties in distinguishing PSP from its mimics. On the other hand, the rapid growth of PSP in group 1 indicated that some PSPs might have distinct behavior from that of traditional benign tumors, and this provides clues for further research, including more cases to validate this phenomenon, and more studies combining multidisciplinary evidence, including radiological, pathological, and other evidence, to explain the possible mechanisms (9,28,29). In addition to that, given the potential for coexistence of PSP with other tumor components, late recurrence and malignant transformation reported in the literature (10,30,31), close monitoring of PSP lesions with regular imaging is essential.
The results of our study should be interpreted in the context of certain limitations. First, the retrospective nature of the study may introduce biases, such as selection bias. Second, the relatively small sample size may affect the generalizability of our findings. Third, the measurement accuracy of current imaging for PSP remains suboptimal, and this might have an impact on the precise calculation of the VDT. Enhancing research in this area and improving preoperative diagnostic accuracy are expected to provide more therapeutic options for patients with PSP, thereby facilitating precision and personalized management for this patient population. Despite these limitations, our study offers valuable insights into the natural history of PSP. While surgical resection remains the suggested treatment (5,13) for PSP, the observed variability in growth rates in this cohort supports individualized approaches—including surveillance for select cases with slowly growing or stable lesions (32) at longer intervals and shorter intervals for rapidly growing cases. However, longer-term follow-up studies with larger cohorts are needed to confirm these findings and to better understand this rare tumor and its growth kinetics.
Conclusions
In conclusion, PSP might have some characteristic features, and radiological features may suggest the diagnosis of PSP. PSPs show heterogeneous growth rates, and this growth heterogeneity challenges the traditional perception of PSP as a uniformly indolent lesion and has significant implications for the clinical management of this rare tumor.
Supplementary
The article’s supplementary files as
Acknowledgments
The authors greatly thank Doctors Xiao Jun Du and Chao Fan for their valuable help. We used Kimi (K2.6, an advanced AI assistant developed by Moonshot AI from China) to translate the original paper, which was written in Chinese, into English. Additionally, we used Kimi for language polishing and revising some sentences. We thank Kimi for this process.
Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. This study was approved by the Institutional Review Board of The Affiliated Hospital of Guizhou Medical University (Nos. 2022-734 and 2023-288), and the requirement for informed consent was waived due to its retrospective nature.
Footnotes
Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-0786/rc
Funding: This work was supported by the Science and Technology Program Project of Guizhou Provincial Department of Science and Technology (No. Qiankehe Basic Research QN[2025]134) and the Cultivate Project for the National Natural Science Foundation of China (Nos. gyfynsfc[2020]-27 and gyfynsfc[2021]-17).
Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-0786/coif). The authors have no conflicts of interest to declare.
Data Sharing Statement
Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-0786/dss
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