PSC is a subtype of NSCLC containing sarcomatoid cells or sarcomatoid differentiation. Compared with other types of NSCLC, PSC is characterized by low incidence, poor differentiation, strong invasions and poor prognosis. PSC is more likely to occur in elderly men, and the onset age is mostly 65–75 years old [8]. However, studies have shown that smoking history has little correlation with survival [9, 10, 11]. The patient we provided had no smoking history and no bad habits. The specific etiology and inducement still need further study.
PSC mostly showed expansion growth, clear boundary, uniform density, lobulation and rare burr signs. PSC is most commonly presented as an isolated peripheral mass in the upper lobe of the lung [12], which usually metastases to the lung, bone, adrenal gland, pleura and brain, and a few metastases to the digestive tract, pancreas, kidney and skin [13]. Due to morphologic differences in tumors, initial or small biopsies may be inaccurate and easily missed. Preoperative diagnosis is difficult, and clinical manifestations lack specificity, early misdiagnosis of pneumonia, lung abscess or tuberculosis, etc. WHO recommends obtaining large enough surgical specimens combined with immunohistochemistry and microscopy to assist diagnosis [14]. Immunohistochemistry is helpful for the diagnosis and differential diagnosis of carcinosarcoma [7]. Chest CT scan suggested homogeneous mass density, irregular annular enhancement or patchy enhancement around the tumor after enhancement, and low enhancement area in the center. PET-CT can improve the diagnostic value of the disease, and it has been reported that PET-CT has a higher average SUVmax value in PSC patients [15, 16].
The onset of PSC is insidic, and the clinical symptoms and signs are mainly related to the lesion site and the size of the mass. The first symptoms are common with dry cough, expectoration, blood in expectoration and chest pain, accompanied by varying degrees of chest tightness, dyspnea, fever, etc., which can also be accidentally discovered during physical examination. PSC grows rapidly and is often found to have formed a large mass, which is more common in patients larger than 5cm. The case we provided had no specific clinical manifestations, and the symptoms were significantly relieved after anti-inflammatory, which delayed the diagnosis of the disease. In addition, the tumor was highly invasive and grew fast, reaching 6.5cm*4.6cm at the time of discovery.
At present, the treatment of PSC is basically the same as that of other types of NSCLC, which mainly adopts surgical treatment, supplemented by radiotherapy and chemotherapy. The overall treatment effect is not as good as that of other types of NSCLC, and it is prone to relapse, with metastasis occurring in 50% within half a year, and the median survival period is significantly shortened after relapse, about 2.6 months [17]. PSC is more aggressive and has a worse prognosis than other types of NSCLC, which may be related to early vascular invasion and metastasis, higher tumor activity of sarcomatoid components, and inactivation of tumor suppressor genes. In a multicenter study of 148 patients with PSC, Lococo et al. found that the overall median survival was 19 months and the 5-year survival was 12.6% [6]. For resectable PSC, lobectomy and mediastinal lymph node dissection were performed, and the 5-year survival rate was 12.6%-54.3% [18]. Platinum-based combined chemotherapy is mainly used in PSC, but PSC is not sensitive to radiotherapy and chemotherapy, and whether it benefits from radiotherapy and chemotherapy in perioperative period needs to be further confirmed [19, 20, 21].
Traditional radiotherapy and chemotherapy have poor efficacy for NSCLC. In recent years, new target drugs keep emerging, bringing survival benefits that cannot be achieved by conventional radiotherapy and chemotherapy for patients with driver gene positive NSCLC, and changing the treatment mode of advanced NSCLC. Due to the rare clinical PSC, there are few studies on the efficacy of targeted therapy. How is the efficacy of new targeted drugs for lung cancer in patients with PSC? Is there a survival benefit? Some scholars have carried out active exploration in order to improve the prognosis of such tumors. Studies have shown that targeted drugs such as androtinib can achieve certain therapeutic effects for PSC patients [22]. The patient refused further anti-tumor therapy after the initial operation, and was readmitted to hospital on the 50th day after the operation due to deterioration of his condition. Subsequently, the patient was diagnosed with tumor recurrence and extensive pleural metastasis. Due to various reasons, the patient was given targeted treatment of antiandrotinib, but no therapeutic effect was achieved, which may be related to missing the best treatment opportunity.
PSC is a rare NSCLC with high invasiveness and poor prognosis. Its clinical and imaging manifestations are non-specific and easy to be misdiagnosed. Pathological and immunohistochemical examinations are the main methods to diagnose PSC, while surgical resection is the main treatment method. Clinicians should improve the understanding of this disease, early detection, early diagnosis, early treatment, to reduce its mortality.