Švajdler M, et al. - In the diagnosis of small cell lung cancer (SCLC) in small biopsy specimens and cytoblocks, researchers compared the diagnostic performance of insulinoma-associated 1 (INSM1) and previously reported composite marker CD56 + p16 + thyroid transcription factor-1 (TTF1). The CD56 + p16 + TTF1 composite marker correctly classified 100% of SCLC cases, and its sensitivity was significantly higher than INSM1 sensitivity. According to findings, INSM1 displayed the lowest classification agreement between paired biopsy and cytoblock specimens. On the other hand, CD56 and p16 exhibited perfect agreement and TTF1 presented moderate agreement. If the result is negative, CD56 is added and p16 and TTF1 are added successively. This approach should detect most, if not all, cases of SCLC while trading sensitivity specificity successively.