Amyloidosis: What does pathology offer? The evolving field of tissue biopsy

Abstract

Since the mid-nineteenth century pathology has followed the convoluted story of amyloidosis, recognized its morphology in tissues and made identification possible using specific staining. Since then, pathology studies have made a significant contribution and advanced knowledge of the disease, so providing valuable information on the pathophysiology of amyloid aggregation and opening the way to clinical studies and non-invasive diagnostic techniques. As amyloidosis is a heterogeneous disease with various organ and tissue deposition patterns, histology evaluation, far from offering a simple yes/no indication of amyloid presence, can provide a wide spectrum of qualitative and quantitative information related to and changing with the etiology of the disease, the comorbidities and the clinical characteristics of patients. With the exception of cardiac transthyretin related amyloidosis cases, which today can be diagnosed using non-biopsy algorithms when stringent clinical criteria are met, tissue biopsy is still an essential tool for a definitive diagnosis in doubtful cases and also to define etiology by typing amyloid fibrils. This review describes the histologic approach to amyloidosis today and the current role of tissue screening biopsy or targeted organ biopsy protocols in the light of present diagnostic algorithms and various clinical situations, with particular focus on endomyocardial and renal biopsies. Special attention is given to techniques for typing amyloid fibril proteins, necessary for the new therapies available today for cardiac transthyretin related amyloidosis and to avoid patients receiving inappropriate chemotherapy in presence of plasma cell dyscrasia unrelated to amyloidosis. As the disease is still burdened with high mortality, the role of tissue biopsy in early diagnosis to assure prompt treatment is also mentioned.

AL-amyloidosis in a Female Patient with a Comorbide Pathology: Challenges with Diagnosis

“…Возможно применение метода сцинтиграфии с меченным йодом сывороточным P-компонентом. При подозрении на AL-А рекомендуется также производить трепанобиопсию костного мозга с подсчетом плазматических клеток и окраской пунктата на амилоид 6 .…”

Characterization of Amyloidosis in the Gastrointestinal Tract With an Emphasis on Histologically Distinct Interstitial Patterns of Deposition and Misinterpretations

“…1 Diagnosis is established through histopathologic evaluation revealing extracellular eosinophilic, hyaline, acellular, amorphous, and homogeneous deposits with a characteristic staining pattern seen with Congo Red and polarizing microscopy. [1][2][3] Although early recognition is crucial for optimal patient management, it is often underdiagnosed. 4,5 Subtype nomenclature is based on the protein from which the amyloid is derived and the structure of the abnormal protein deposited.…”

“…In addition, Congo Red-negative cases have been documented, adding to the difficulty in establishing a diagnosis. 3,14 Improved recognition of histopathological features associated with amyloid deposition could improve recognition and early diagnosis. This retrospective observational study aimed to characterize the most commonly observed deposition patterns in the GIT and evaluate key quality metrics, including misinterpretations, to improve recognition and provide insight for accurate diagnosis.…”

“…Amyloidosis is a complex disease caused by pathologic extracellular fibrillary protein deposition arranged in a β-pleated sheet configuration, often leading to tissue and organ dysfunction 1 . Diagnosis is established through histopathologic evaluation revealing extracellular eosinophilic, hyaline, acellular, amorphous, and homogeneous deposits with a characteristic staining pattern seen with Congo Red and polarizing microscopy 1–3 . Although early recognition is crucial for optimal patient management, it is often underdiagnosed 4,5 …”

“…While amyloid deposition can often be confirmed with a Congo Red stain, this stain is not consistently performed, even when a clinical indication for performing the stain is listed on the requisition sheet. In addition, Congo Red-negative cases have been documented, adding to the difficulty in establishing a diagnosis 3,14 …”