AA Amyloidosis Revealing HHV-8-Associated Multicentric Castleman Disease: A Case Report and Literature Review

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Background/Objectives: Multicentric Castleman disease (MCD) is a rare systemic lymphoproliferative disorder driven by interleukin-6 (IL-6) dysregulation and frequently associated with human herpesvirus 8 (HHV-8) infection. AA amyloidosis is a severe complication of chronic inflammatory states, resulting from extracellular deposition of serum amyloid A (SAA) protein. We report a case of HHV-8-associated MCD revealed by AA amyloidosis with hepatic and salivary gland involvement. Methods: A 40-year-old Algerian woman with a six-year history of progressive gastrointestinal symptoms and chronic inflammation was evaluated for biopsy-proven AA amyloidosis involving the liver and minor salivary glands. Diagnostic workup included HHV-8 PCR, autoantibody screening, MEFV gene mutation analysis, bone marrow examination, and CT imaging. Results: HHV-8 viremia was positive (25,000 copies/mL), while autoimmune and genetic testing, including MEFV mutation screening, were negative. Clinical findings included chronic hypotension, normocytic anemia with hemolytic features, and subcentimeter lymphadenopathy on CT. A diagnosis of HHV-8-associated MCD with secondary AA amyloidosis was established. The patient was treated with rituximab (375 mg/m² weekly for four weeks) combined with valganciclovir, resulting in viral clearance, normalization of inflammatory markers, and improvement in hemoglobin. Conclusions: MCD should be considered in patients with unexplained chronic inflammation and AA amyloidosis. Early recognition and targeted therapy with rituximab are essential to prevent irreversible organ damage. Excisional lymph node biopsy with HHV-8 immunostaining is critical for definitive diagnosis.

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