Combined small cell carcinoma with giant cell carcinoma component of the lung: A case successfully diagnosed by computed tomography-guided fine-needle aspiration cytology.

Combined small cell lung carcinoma (SCLC) is a rare variant of SCLC and is defined as a mixture of SCLC and non-SCLC components. Although any histopathological subtype may be present as a non-SCLC component, the presence of pleomorphic carcinoma components are extremely rare. The present report describes the first documented cytological features of combined SCLC with a giant cell carcinoma component. A 50-year-old Japanese female with a history of smoking presented with a mass lesion in the left lung. Computed tomography-guided fine-needle aspiration cytology and needle biopsy were performed, followed by a lobectomy. A Papanicolaou smear revealed the presence of two distinct neoplastic components in a necrotic background. One component was SCLC, which comprised small-sized neoplastic cells containing scant cytoplasm and round to oval nuclei with dispersed granular chromatin without nucleoli. The other component was giant cell carcinoma, which was composed of large-sized neoplastic cells containing irregular large hyperchromatic nuclei (approximately 7 to 10 times larger than those of SCLC). SCLC was demonstrated in the biopsy specimen, however no giant cell carcinoma component was present. Histopathological study of the lobectomy specimen verified a diagnosis of combined SCLC with giant cell carcinoma component. Both SCLC and giant cell carcinoma exhibit characteristic cytological features, therefore, albeit extremely rare, careful observation may lead to a correct diagnosis of combined SCLC in the cytological specimen.