Case Report: Rare Pulmonary Sclerosing Pneumocytoma: Large, Multiple, Metastatic, and Fatal

Revisiting Pulmonary Sclerosing Pneumocytoma

Pulmonary sclerosing pneumocytoma (PSP) is a quite rare tumor outside Eastern countries. This rarity, together with a wide histological appearance, makes its correct identification a diagnostic challenge for pathologists under the microscope. Historically, PSP was considered a vascular-derived neoplasm (sclerosing hemangioma), but its immunohistochemical profile clearly supports its epithelial origin. No specific molecular fingerprint has been detected so far. This short narrative revisits the clinical, histological, immunohistochemical, and molecular aspects of this tumor, paying special attention to some controversial points still not well clarified, i.e., clinical aggressiveness and metastatic spread, multifocality, the supposed development of sarcomatoid change in a subset of cases, and tumor associations with lung adenocarcinoma and/or well-differentiated neuroendocrine hyperplasia/tumors. The specific diagnostic difficulties on fine-needle aspiration cytology/biopsy and perioperative frozen sections are also highlighted. Finally, a teaching case of tumor concurrence of lung adenocarcinoma, neuroendocrine lesions, and PSP, paradigmatic of tumor association in this context, is also presented.

Pulmonary sclerosing pneumocytoma - approaching a solitary pulmonary nodule and the limitations of risk prediction models

Our case is an asymptomatic, non-smoking, East Asian woman in her 40s presenting with a solitary pulmonary nodule (SPN). On imaging, the 1.7 cm solid SPN located in the left upper lobe, was rounded in morphology and moderately fluorodeoxyglucose avid. The clinical pretest probability of malignancy assessed by risk prediction models such as Brock (19.1%), Mayo Clinic (56.2%) and Herder (51.4%) was discordant. She underwent a percutaneous CT-guided needle biopsy, establishing a diagnosis of pulmonary sclerosing pneumocytoma (PSP). PSP is a rare benign lung neoplasm with indolent growth characteristics that has been described predominantly in non-smoking women. Our case illustrates the limitations of applying existing risk prediction models in Asia where the epidemiology and biology of lung cancer differ significantly from the Caucasian derivation cohorts. Additionally, the risk models do not account for tuberculosis, which is endemic in Asia and can mimic malignancy. Non-surgical lung biopsy remains useful in minimising unnecessary thoracotomy.

Giant pulmonary sclerosing pneumocytoma with potentially malignant biological behavior: a case report and literature review

Background

Pulmonary sclerosing pneumocytoma (PSP) is a rare benign lung tumor which generally presents as a solitary pulmonary nodule in middle-aged females. However, the PSP in some patients exhibits potentially malignant biological behavior, with recurrence and lymphatic or distant metastasis being observed.

Case Description

We encountered a case of a 46-year-old female with an inordinately massive tumor 9.5 cm in diameter and a relatively high Ki-67 proliferation rate. Fine needle aspiration (FNA) played a significant but limited role in the preoperative diagnosis: the computed tomography (CT)-guided lung puncture biopsy was consistent with the typical pathology of PSP; however, endobronchial ultrasound-guided transbronchial lung biopsy (EBUS-TBLB) could not provide a definitive diagnosis. The patient ultimately underwent thoracoscopic resection and mediastinal lymph node dissection. Here, we provide a review of the literature on patients with PSP with malignant biological behavior to raise awareness of the malignant potential of PSP and describe our experience to inform future management.

Conclusions

PSP lacks specificity in its clinical and radiological characteristics and has complex pathological manifestations. FNA is valuable in the diagnosis and differential diagnosis of PSP but involves the risk of misdiagnosis or missed diagnosis. Additionally, we believe that the accepted benign features of PSP need to be updated and that the potential malignant features of PSP should be carefully monitored. Surgical resection is curative but strict follow-up is crucial.

Case report: Rare epithelioid hemangioendothelioma occurs in both main bronchus and lung

Pulmonary epithelioid hemangioendothelioma (PEH) is a rare vascular tumor of endothelial origin with low- to intermediate-grade malignant potentials. Since there is no characteristic clinical or biological marker available for PEH, most cases require a surgical lung biopsy for diagnosis. To date, although some patients with PEH reported in the literature were diagnosed through bronchoscopic biopsy, most of the patients still underwent surgical lung biopsy for confirmation. In this case report, we present a rare case diagnosed as PEH through endobronchial biopsies due to the presence of an intraluminal mass that blocked the trachea and caused atelectasis in the right upper lobe. Moreover, since surgery was not appropriate for this patient with unresectable bilateral multiple nodules, we adopted genetic analysis using NGS to provide a guide for personalized treatment. Then, based on the NGS results, the patient was treated with anti-PD-1 mAb and sirolimus for 1 year and has been stable in a 1-year follow-up examination.

Pulmonary sclerosing pneumocytoma and mortality risk

Background

Surgical resection is usually recommended for the treatment of pulmonary sclerosing pneumocytoma (PSP). However, no comparative study has demonstrated that surgical resection leads to improved outcomes. We aimed to compare all-cause mortality between patients with PSP who underwent surgery or did not and those without PSP.

Methods

Participants aged ≥18 years who had pathologically diagnosed PSP between 2001 to 2018, at 3 hospitals were included. Randomly selected (up to 1:5) age-, sex-, and smoking status-matched controls without PSP who were randomly selected from those who underwent health checkups including chest CT were included. Mortality was compared using Kaplan–Meier estimates and Cox proportional hazards regression models. Literature review of studies reporting PSP was also conducted.

Results

This study included 107 patients with PSP (surgery:non-surgery, 80:27) and 520 matched controls. There were no cases of lymph node or distant metastasis, recurrence, or mortality from PSP. No significant difference in all-cause mortality risk was observed between the PSP surgery, PSP non-surgery, and non-PSP groups (log rank test P = 0.78) (PSP surgery vs. non-PSP: adjusted hazards ratio [aHR], 1.80; 95% confidence interval [CI], 0.22–14.6; PSP non-surgery vs. non-PSP: aHR, 0.77; 95% CI, 0.15–3.86; PSP surgery vs. PSP non-surgery: aHR, 2.35; 95% CI, 0.20–28.2). In the literature review, we identified 3469 patients with PSP from 355 studies. Only 1.33% of these patients reported metastasis, recurrence, or death.

Conclusions

All-cause mortality did not differ between patients with PSP and those without, irrespective of undergoing surgery. Our study and the literature review suggest that PSP has less impact on increased mortality risk.

Clinical Characteristics of Malignant Pulmonary Sclerosing Pneumocytoma Based on a Study of 46 Cases Worldwide

Objective

To analyze the clinical characteristics of patients with malignant pulmonary sclerosing pneumocytoma (PSP) with metastasis, recurrence, and growth and to improve clinicians’ understanding of PSP in patients with malignant tumor characteristics.

Methods

A total of 46 PSP patients with malignant tumor characteristics were identified in the literature search and compared with 38 patients with benign PSP diagnosed and treated in our hospital in the past 5 years. We explored the pathogenesis, clinical symptoms, diagnostic methods, treatment strategies and prognosis of PSP patients with malignant tumor.

Results

The characteristics of young age (≤41 years old), larger tumor (≥36mm), lymph node metastasis and distribution in East Asians are indicative of PSP with malignant potential. Such patients should undergo segmental resection or lobectomy, combined with necessary lymph node dissection or biopsy. All patients with PSP should have an entire course of follow-up management, because they may have an adverse prognosis such as recurrence, growth, metastasis, and even death.

Conclusion

PSP has the potential for malignancy. Anatomical lobectomy or segmental resection combined with lymph node dissection should be performed in PSP with some specific characteristics. Inappropriate diagnosis and treatment may lead to poor prognosis in PSP patients.