Rheumatological Manifestations of Systemic Amyloidosis: A Retrospective Single-Centre Study From a Tertiary Care Hospital in India

OBJECTIVE: Systemic amyloidosis may present with rheumatological features that mimic inflammatory arthritis, frequently leading to significant diagnostic delays. This study describes the clinical profile, patterns of organ involvement, and clinical outcomes of patients with systemic amyloidosis who presented to a rheumatology clinic. METHODS: A retrospective observational study with review of electronic medical records from January 2010 to December 2024 at Christian Medical College, Vellore, identified patients diagnosed with amyloidosis who presented with specific rheumatological complaints. Data on clinical features, organ involvement, biopsy findings, amyloid typing, treatment, and survival were analyzed. RESULTS: In this retrospective observational study spanning January 2010 to December 2024 and including 24 patients with systemic amyloidosis, amyloid A (AA) amyloidosis was the most prevalent type (n=11, 45.8%), followed by amyloid light-chain (AL) amyloidosis (n=seven, 29.2%), with the remaining six cases (25.0%) classified as amyloidosis of unspecified type. Of 24 patients, the most common presenting features were peripheral joint pain (15 patients, 62.5%), early morning stiffness (15 patients, 62.5%), and axial joint pain (nine patients, 37.5%). Classic signs included macroglossia (four patients, 16.6%), carpal tunnel syndrome (three patients, 12.5%), and periorbital purpura (three patients, 12.5%). Renal involvement with proteinuria exceeding 1 gram in 24 hours was seen in 12 patients (50%), and chronic kidney disease was noted in five patients (20.8%). Cardiac amyloidosis was confirmed in seven patients (29%). Biopsy showed vessel wall deposition in all cases (24 patients, 100%). Amyloid typing revealed AL in seven patients, AA in 11, and unspecified types in six. AA amyloidosis showed significantly better survival (90.9%, one death in 11 patients) than AL amyloidosis (14.3%, six deaths in seven patients), yielding a highly significant difference (p = 0.0033). This confirms markedly poorer survival in the AL group compared to the AA group. Cardiac involvement was associated with markedly poorer prognosis, accounting for six of the seven total deaths (p = 0.0003). CONCLUSION: Systemic amyloidosis must remain a key differential diagnosis for any patient presenting with atypical inflammatory arthritis accompanied by early morning stiffness, especially when features such as soft tissue expansion or cutaneous bleeding are present. A high index of clinical suspicion is essential, particularly when joint symptoms are accompanied by specific red-flag signs such as macroglossia, carpal tunnel syndrome, or periorbital purpura. Cardiac involvement portends poor prognosis, particularly in the AL type.