Large pulmonary sclerosing pneumocytoma with massive necrosis and vascular invasion: a case report

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.

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.

Pulmonary sclerosing pneumocytoma masquerading adenocarcinoma with co-existing BRAF V600E and PTEN mutation

We report a case of a massive primary sclerosing pneumocytoma (PSP) involving the right lower lobe adhering esophagus with small synchronous PSP on the superior segment of the left lower lobe with concurrent mutation for B-RAF proto-oncogene, serine/threonine kinase (BRAF V600E), and phosphatase and tensin homolog (PTEN) gene in a young female. She underwent right lower lobectomy and mediastinal lymph node dissection under single lung ventilation with tumor-free margins on diagnosis-based findings of preoperative computed tomography-guided biopsy and positron emission tomography. Histopathology was suggestive of PSP-papillary variant with concurrent mutation of BRAF V600E and PTEN genes. Post-operative follow-up at four weeks was uneventful. She has to undergo wedge resection for the contralateral disease after six weeks following recovery from the first surgery.

Huge Pulmonary Sclerosing Pneumocytoma with Endobronchial Invasion: A Case Report with a Literature Review

Pulmonary sclerosing pneumocytoma (PSP) is a tumor of pneumocytic origin that is classified as a benign neoplasm. To date, aggressive behavior of this tumor has rarely been reported. Here, we describe a case of a 56-year-old woman with a huge, 19-cm PSP that resulted in mediastinal shift and showed microscopic endobronchial invasion and necrosis. The differential diagnosis included malignant mesenchymal tumors, such as solitary fibrous tumor; however, PSP was confirmed based on the characteristic thyroid transcription factor 1 positivity and membranous expression of Ki-67 on immunohistochemical staining of tumor cells.

Pulmonary Sclerosing Pneumocytoma: A Pre and Intraoperative Diagnostic Challenge. Report of Two Cases and Review of the Literature

Pulmonary sclerosing pneumocytoma is a rare benign pulmonary tumor of primitive epithelial origin. Because of the unspecific radiological features mimicking malignancies and its histological heterogeneity, the differential diagnosis with adenocarcinoma and carcinoid tumors is still challenging. We report our experience of two cases of sclerosing pneumocytoma, as well as a review of the literature. Immunohistochemical findings showed intense staining of the cuboidal epithelial cells for cytokeratin-pool and TTF-1, with focal positivity for progesterone receptors. Round and spindle cells expressed positivity for vimentin, TTF-1 and focally for the progesterone receptor. Cytologic diagnosis of pulmonary pneumocytoma requires the identification of its dual cell population, made up of abundant stromal cells and fewer surface cells. Since the pre- and intraoperative diagnosis should guide surgical decision making, obtaining a sufficient specimen size to find representative material in the cell block is of paramount importance.

Molecular Genetic Landscape of Sclerosing Pneumocytomas

OBJECTIVES

Sclerosing pneumocytomas are rare pulmonary neoplasms that are typically benign. However, rare patients experience progressive disease, and therapy targeting specific genetic underpinnings could be an attractive therapeutic option. Recent studies have found recurrent AKT 1 mutations in sclerosing pneumocytoma, but little is known about whether oncogenic fusion genes may also be present.

METHODS

To better understand the genetic background, 10 sclerosing pneumocytomas were subjected to next-generation sequencing cancer mutation panel testing (n = 9) and/or RNA sequencing (n = 3). The patients were all women (average age, 47 years; range, 17-74 years).

RESULTS

Eight patients had solitary sclerosing pneumocytomas, while one had two tumors, and one had many bilateral tumors. Recurrent mutations were noted in genes involved in the mTOR pathway, including AKT1, PIK3R1, and PTEN. AKT1 alterations were particularly common, present in 78%. No recurrent genetic fusions were identified. The patient in our study with multiple bilateral lesions was treated with the mammalian target of rapamycin (mTOR) inhibitor everolimus, with no objective radiographic evidence of treatment response after 4 months.

CONCLUSIONS

Our data further support that abnormal activation of the mTOR pathway is a consistent genetic event in sclerosing pneumocytoma. This warrants further exploration to determine if mTOR pathway inhibitors may be effective in patients with metastatic or recurrent disease.