Paraneoplastic pemphigus (PNP) is an autoimmune disorder that is almost always linked to an underlying neoplasia. General radiologists are usually not aware of what kind of neoplasia can be associated with PNP. Therefore, this study evaluates the effect of a dermatology lecture on radiologists' neoplasia diagnosis performance. Two radiologists evaluated thoracoabdominal computed tomography (CT) examination images of 43 patients with PNP in separate reading sessions blinded to each other's assessments. Six months after the first CT image evaluation session, the two radiologists attended a lecture by two dermatologists about PNP, and 6 months later the two radiologists assessed the same CT examinations again. Statistical analysis showed statistically significant differences in CT sensitivity between the first and the second round of image evaluation for both radiologists (reader 1: p = 0.0313; reader 2: p = 0.0156). This is the first study to evaluate the effectiveness of a dermatology lecture on diagnostic performance. It is very important for radiologists to be familiar with the particular neoplasms that can be associated with PNP because this can have a direct clinical impact on diagnostic performance.