Combined small cell lung carcinoma harboring ALK rearrangement: A case report and literature review

Abstract

Combined small cell lung cancer (c-SCLC) is a relatively rare subtype of SCLC and is defined by the combination of SCLC and any elements of non-small cell carcinoma (NSCLC). Standard chemotherapy for patients with c-SCLC has not yet been established. Gene mutations such as epidermal growth factor receptor (EGFR) mutations may be detected in patients with c-SCLC. However, little is known about anaplastic lymphoma kinase (ALK) rearrangement in c-SCLC patients. Here, we report a young female patient who was successfully treated with alectinib for ALK-positive c-SCLC after failure of immunochemotherapy for SCLC and cytotoxic chemotherapy for adenocarcinoma. Moreover, we performed a literature review of EGFR- or ALK-positive c-SCLC patients. Our report suggests that ALK testing may be justified in patients with SCLC that contain an adenocarcinoma component. KEY POINTS: SIGNIFICANT FINDINGS OF THE STUDY: • This is the first report describing the treatment course comprising immunochemotherapy and ALK-TKI in a patient with c-SCLC harboring ALK rearrangement. WHAT THIS STUDY ADDS: • Our case and literature review suggest that although ALK mutation is rare in patients with c-SCLC, its identification and treatment with ALK-TKIs may contribute to clinical benefits.

Keywords: ALK; Alectinib; combined small cell carcinoma; immunochemotherapy; literature review.

Figure 1

Histological findings on the transbronchial lung biopsy revealed two different components. (a) Hematoxylin and eosin staining showing small cell carcinoma; (b) hematoxylin and eosin staining showing adenocarcinoma. (c, d) Thyroid transcription factor‐1 (TTF‐1) expression in SCLC and adenocarcinoma components. (e, f) Synaptophysin expression in SCLC and adenocarcinoma components. (g, h) Testing for ALK rearrangement using immunohistochemistry showed strong positivity for ALK in both components.

Figure 2

Chest computed tomography (CT) scan showing (a) the primary tumor in the right lower lobe (arrow) and pleural effusion in the right hemithorax. (b) CT scan at one month after alectinib initiation showed a remarkable shrinkage of the primary tumor (arrow) and decrease in the in the right pleural effusion.