Combined Small Cell Carcinoma of the Lung or a Coexistent Small Cell and Adenocarcinoma of the Lung?

Abstract

SESSION TITLE: Lung Cancer Cases - Student/Resident SESSION TYPE: Student/Resident Case Report Slide PRESENTED ON: Sunday, October 25, 2015 at 03:15 PM - 04:15 PM INTRODUCTION: Combined small cell carcinomas (c-SCLC) are multiphasic lung cancers originating in lung tissue containing a component of small cell lung carcinoma (SCLC) admixed with one (or more) components of non-small cell lung carcinoma (NSCLC). CASE PRESENTATION: 66 y/o female presented to the hospital with cough of 3 weeks duration. She had been diagnosed with lung cancer 6 months prior to this presentation. At that time her biopsy revealed poorly differentiated lung adenocarcinoma (strong nuclear positivity for TTF-1 and focal positivity for Napsin-A) with EGFR mutation in exon 19 and she was started on chemotherapy with Erlotinib. During this admission CT scan of the chest revealed obstruction of right bronchus due to lymphadenopathy. She underwent bronchoscopy with ultrasound-guided biopsy of the lymph node and endobronchial stent placement. The biopsy revealed tumor cells positive for TTF-1, CD56, synaptophysin and NSE, but negative for chromogranin. An immunostain for Ki-67 shows 70% positivity in the tumor cells. Thus a diagnosis of small cell carcinoma was made. She was started on chemotherapy with carboplatin and etoposide. Unfortunately after the second cycle, she developed neutropenic fever and septic shock without response to antibiotics. At this point patient opted comfort as the primary goal. DISCUSSION: Lung cancer is the leading cause of cancer death for both men and women. SCLC comprises more than 90% of all small cell lung cancer cases. The remaining 10% are mixed small cell/non-small cell carcinomas called as c-SCLC. In our patient it is difficult to determine if the patient had a co-existing adenocarcinoma and a SCLC or a c-SCLC, which was diagnosed as adenocarcinoma during the first biopsy. It is also interesting to note that our patient had an EGFR mutation. EGFR mutation is rare in small cell lung cancer, and cases harboring EGFR mutations were more likely to be combined with adenocarcinoma. Inferior survival has been reported for patients with mixed carcinomas compared with patients having small cell carcinoma without a non-small cell component. However more recent reports have shown that these patients tend to have more localized, sometimes surgically resectable disease and a more favorable prognosis. Current thinking is that patients who have mixed histologies, should be treated as those the entire tumor is a small cell lung cancer. However, all patients should be managed individually based upon their stage of disease, age, and general medical condition. CONCLUSIONS: Due to the multiphasic nature of c-SCLC it can be difficult to distinguish it from a co-existing small cell and non-small cell cancer of the lung. When diagnosed, it should be treated as small cell lung cancer and the treatment should be based on the individual needs of the patient. Reference #1: [1] Mangum MD et al. Combined small-cell and non-small-cell lung cancer. J Clin Oncol. 1989 May;7(5):607-12. DISCLOSURE: The following authors have nothing to disclose: Abhishek Agarwal, Abhinav Agrawal, Karim Nathan, Vinay Palli, Deborah Park, Erin Jepsen No Product/Research Disclosure Information