Post-operative immunohistochemical diagnosis of two synchronous primary non-small cell lung cancers in a single lobe.

Synchronous primary non-small cell lung cancers (NSCLC) are rare and may be discovered unexpectedly following lung resection. Discrimination from intrapulmonary metastases is important to guide treatment and prognosis but is difficult solely on clinical or radiological findings. Histopathological evaluation with immunohistochemistry (IHC) markers can prove decisive and should feature in the diagnostic algorithm of such patients. We report a rare case of two synchronous primary NSCLCs diagnosed post operatively following pathological examination of the resected lobe, highlighting the value of IHC and discuss the management of such patients.