Shared decision-making (SDM) involves patients and clinicians making medical decisions as equal partners, combining professional expertise with patients' values and preferences. While increasingly applied in treatment and screening, SDM is rarely used in the diagnostic process, despite its potential value. Diagnostic decision-making differs fundamentally from treatment choices: uncertainty plays a larger role, evidence is often limited, and decisions unfold over time. To explore when SDM is most relevant, we analyzed malpractice claims related to diagnostic decisions in general practice. From 90 anonymized cases, six themes emerged where perspectives of doctors and patients diverged and SDM could add value: risk assessment, time as a diagnostic tool, consequences of testing, practical execution, re-evaluation of a diagnosis, and individual context. Addressing these themes through SDM may improve mutual understanding, prevent delays, enhance patient-centeredness, and reduce harm. SDM should therefore be considered a structural component of diagnostic practice.