AA amyloidosis with multiorgan involvement secondary to severe hidradenitis suppurativa

RATIONALE: Secondary (amyloid A [AA]) amyloidosis is a rare but serious systemic complication of chronic inflammatory disorders. Hidradenitis suppurativa (HS) represents an uncommon cause, with approximately 20 cases reported, usually associated with severe, extensive, or long-standing disease. PATIENT CONCERNS: A 67-year-old man with severe anogenital HS (Hurley stage III), partially controlled with off-label ustekinumab, developed progressive lower-limb edema, dyspnea, distal limb hypesthesia, and weakness, eventually requiring a wheelchair. DIAGNOSES: Laboratory investigations revealed persistently elevated inflammatory markers, severe hypoalbuminemia (16.4 g/L), nephrotic-range proteinuria (14 g/24 hours), and bilateral pleural effusions. Cardiac assessment showed increased left ventricular wall thickness, low QRS voltage on electrocardiography, and preserved systolic function, while neurological studies demonstrated severe axonal sensorimotor polyneuropathy. Renal biopsy showed Congo red-positive deposits with apple-green birefringence and positive immunohistochemical staining for amyloid A, confirming AA amyloidosis. INTERVENTIONS: Treatment included systemic corticosteroids, initiation of secukinumab (anti-interleukin-17A), intravenous ertapenem as induction therapy for severe HS, angiotensin-converting enzyme inhibitors, nutritional support, diuretics, and prophylactic anticoagulation. OUTCOMES: Despite a decrease in inflammatory markers and a partial reduction in nephrotic-range proteinuria, severe hypoalbuminemia and refractory anasarca persisted. The patient died approximately 5 to 6 weeks after diagnosis because of complications related to advanced systemic disease. LESSONS: This case illustrates that persistent systemic inflammation may occur in patients with severe or refractory HS despite apparent clinical stability of skin lesions. Although AA amyloidosis remains a rare complication, unexplained proteinuria or progressive hypoalbuminemia in selected high-risk patients should prompt consideration of AA amyloidosis to allow timely diagnostic evaluation before irreversible organ damage develops.