Case Report: Diagnostic overshadowing in a patient with major depressive symptoms later diagnosed with systemic amyloidosis.

Background: The symptoms of depression may overlap with the early manifestations of systemic diseases, resulting in diagnostic masking. Amyloidosis is a multisystemic disease that has the potential to affect the heart, kidneys, nervous system, liver, lungs and intestines. Cardiac involvement is the leading cause of morbidity and mortality. As the symptoms of systemic amyloidosis can be non-specific and like those of a depressive episode in its early stages, there can be delays in diagnosis when patients are initially diagnosed depressed. Case presentation: We report the case of a 57-year-old male patient who was initially diagnosed with a major depressive episode. During treatment, he developed recurrent episodes of hypotension and syncope, which were initially attributed to his psychiatric condition and medication-related factors. As his clinical condition progressively deteriorated, a renal biopsy was performed, which ultimately confirmed a diagnosis of systemic amyloidosis with cardiac involvement and acute decompensated heart failure. Conclusion: This case suggests that, at the interface between psychiatry and somatic medicine, diagnostic overshadowing, anchoring bias, and fragmented care may jointly contribute to delayed recognition of systemic amyloidosis, particularly cardiac amyloidosis. In cases where patients present with depression-like manifestations, orthostatic hypotension, and nonspecific multisystem symptoms, clinicians should remain highly alert to persistently progressive physiological abnormalities and dynamically re-evaluate potential underlying somatic etiologies as new evidence emerges. Greater interdisciplinary awareness and reduced cognitive bias may help to reduce diagnostic delay and optimize multidisciplinary management. Further investigation is required to explain the mechanistic links between systemic amyloidosis and depressive symptoms.