Introduction: Lung carcinoma has become a leading cause of death in the USA, which has led to an increase in differentiation including multiple sub-types.  Pulmonary Sarcomatoid carcinoma (PSC) is one sub-type that is characterized as a poorly differentiated non-small cell carcinoma (NSCC) containing both sarcoma and sarcoma-like components with spindle or giant cell features therefore It is difficult to distinguish PSC from true sarcomas. PSC is uncommon, representing less than 1% of all lung cancers. Typically, it occurs in older males with extensive smoking history, and has a predilection to upper lobe involvement.  Limited data has shown most cases of Sarcomatoid carcinomas occur with advanced local disease and metastasis. The diagnosis is based on histopathological analysis and immunohistochemical staining for further characterization. This clinical vignette aims to present a patient incidentally found to have PSC and highlights the overall clinical course.

Case Presentation/Final Diagnosis: A 51 y.o. white male presented with worsening thoracic level back pain over the last 3 months. He also presented with B-type symptoms including fever, weight loss and malaise. He had an extensive smoking history.  Workup revealed a 5 cm left superior mediastinal mass encasing multiple great vessels as well as the trachea and esophagus with pathological fractures in T2 and T3 vertebral bodies. PET CT did not show distant organ involvement. The lung biopsy with Immunostaining showed the mass was a poorly differentiated carcinoma with spindle cells and Sarcomatoid features. Genetic studies showed both Epidermal growth factor receptor (EGFR) and monoclonal antibodies directed against the programmed death 1 (PDL1) mutation. He was not a candidate for resection due to extensive encasement of surrounding structures, and was started on palliative radiation therapy.  The patient only completed 7 sessions before presenting to hospital for acute hypoxic respiratory failure. Repeat scan showed enlargement of the mass; He was transitioned to hospice and died 2 months after initial diagnosis.

Conclusions: PSC remains poorly explored. Typically PSC occurs in older male smokers, however this patient was 51. The histological and immunohistochemical characteristics of this tumor type are specific and starkly different from NSCC, resulting in an aggressive entity with advanced local invasion. Conventional chemotherapy did not show satisfactory results, and future studies are needed to explore the molecular profile of these tumors in order to determine the best therapeutic approach. The aggressive nature of his disease and poor response to treatment is known with PSC. Ultimate 5 year survival is ~25%. By presenting this case with its overall clinical course, the data gathered can further add to the body of knowledge of this rare disease and aid in the development of successful treatment.