Inflammatory Sarcomatoid Carcinoma: A Case Report and Discussion of a Malignant Tumor With Benign Appearance

Infarct-Like Spindle Cell Carcinoma of the Lung: Clinicopathologic, Immunohistochemical, and Molecular Analysis of 4 Cases

Pulmonary spindle cell carcinoma is a rare and aggressive malignancy that often mimics benign conditions. We report 4 cases that simulate a pulmonary infarction, 2 of which were misdiagnosed. Patients were 3 men and 1 woman, smokers, presenting chest pain. All cases appeared as pleural-based, solitary, and rounded nodules. Patients underwent wedge resections followed by adjuvant chemotherapy (3/4) but died of disease. At histology, lesions consisted of widely necrotic nodules surrounded by organizing fibrosis and pleuritis. Examination and immunostains with pan-cytokeratins and epithelial membrane antigen (EMA) revealed atypical spindle cells encircling necrotic tissue and involving the vascular wall. Positive staining with PD-L1 was noted. Molecular analysis showed KRAS (2/4) and TP53 (1/4) mutations, whereas EGFR, ALK, and ROS1 alterations were not detected. Although in a limited series, these cases further evidence the treacherous appearance of spindle cell carcinomas and the need for careful attention when examining pulmonary infarcted tissue, thus requiring extensive sampling, meticulous examination of vascular structures, and immunostaining with cytokeratins.

Approaches to Tumor Classification in Pulmonary Sarcomatoid Carcinoma

Pulmonary sarcomatoid carcinoma (PSC) is a heterogeneous category of primary lung cancer accounting from 0.3% to 3% of all primary lung malignancies. According to the most recent 2015 World Health Organization (WHO) classification, PSC includes several different variants of malignant epithelial tumors (carcinomas) histologically mimicking sarcomas showing or entirely lacking a conventional component of non-small cell lung cancer (NSCLC). Thus, this rare subheading of lung neoplasms includes pleomorphic carcinoma, spindle cell carcinoma, giant cell carcinoma, pulmonary blastoma, and carcinosarcoma. A diagnosis of PSC may be suspected on small biopsy or cytology, but commonly requires a surgical resection to reach a conclusive definition. The majority of patients with PSC consists of elderly, smoking men with a large, peripheral mass characterized by well-defined margins. However, presentation with a central, polypoid endobronchial lesion is well-documented, particularly in pleomorphic carcinoma and carcinosarcoma showing a squamous cell carcinoma component. As expected, PSC may pose diagnostic problems and immunohistochemistry is largely used when pathologists deal these tumors in routine practice. Indeed, PSC tends to overexpress molecules associated with the epithelial-to-mesenchymal transition, such as vimentin, but the panel of immunostains also includes epithelial markers (cytokeratins, EMA), TTF-1, p40 and negative markers (e.g., melanocytic, mesothelial and sarcoma-related primary antibodies). Although rare, PSC has increased their interest among oncologist community for different reasons: a. identification of the epithelial-to-mesenchymal phenomenon as a major mechanism of secondary resistance to tyrosine kinase inhibitors; b. over-expression of PD-L1 and effective treatment with immunotherapy; c. identification of c-MET exon 14 skipping mutation representing an effective target to crizotinib and other specific inhibitors. In this review, the feasibility of the diagnosis of PSC, its differential diagnosis and novel molecular findings characterizing this group of lung tumor are discussed.

Operative wound implantation of inflammatory sarcomatoid carcinoma of the lung

We describe a patient with iatrogenic chest wall implantation of inflammatory sarcomatoid carcinoma. A 43-year-old man underwent right partial lung resection for hemopneumothorax, with large bullae and an alveolar accumulation of histiocytes found on pathology. Three months later, a subcutaneous tumor appeared at a thoracoscopic port site. Needle aspiration of this tumor suggested a malignant neoplasm; therefore, a right upper lobectomy and chest wall resection were performed, and a pathologic diagnosis of sarcomatoid carcinoma was made. Pathologic reexamination of the original sample suggested that the tumor has been implanted in the patient's chest wall at the time of the first operation.

Review article: pulmonary sarcomatoid carcinomas: a practical overview

Pulmonary sarcomatoid carcinomas (PSCs) are currently defined as poorly differentiated non-small-cell carcinomas containing a component with sarcoma or sarcoma-like (spindle and/or giant cell) features. They consist of 5 major histological variants, namely pleomorphic carcinoma, spindle cell carcinoma, giant cell carcinoma, carcinosarcoma, and pulmonary blastoma. The segregation of PSCs into a distinct clinicopathologic entity seems justified on the basis of morphologic, behavioral, and genotypic/phenotypic attributes. As a group, PSCs generally run an aggressive clinical course and may cause major difficulties in the differential diagnosis with other primary and secondary malignancies of the lung. At present, PSCs are believed to represent a family of carcinomas "in transition," in which diverse pathways of clonal evolution account for histological differences of a common ancestor lesion. The sarcomatous or sarcomatoid component of these tumors is thought to derive from carcinoma cells during the progression of carcinogenesis through the activation of an epithelial-mesenchymal transition program leading to sarcomatous transformation or metaplasia (conversion paradigm). Conceivably, targeting the epithelial-mesenchymal transition program could become a valid therapeutic strategy for these life-threatening tumors, whose sensitivity to current medical manipulation is disappointing.