Heavy chain (AH) amyloidosis is a rare form of primary systemic amyloidosis that predominantly affects the kidneys and can lead to nephrotic syndrome. It is marked by the deposition of amyloid fibrils derived from immunoglobulin (Ig)-heavy chains. Monoclonal immunoglobulin deposition disease is a similarly rare disorder involving deposition of nonfibrillar and Congo red-negative monotypic Ig molecules in basement membranes. It can be derived from Ig light chains, Ig heavy chains, or Ig light and heavy chains. Cases of combined amyloidosis and monoclonal immunoglobulin deposition disease are exceedingly rare. Only a handful of concomitant amyloidosis and heavy chain deposition disease have been previously reported, and the spectrum of such diagnoses is poorly described. We describe a case of concomitant IgG4-type AH amyloidosis and heavy chain deposition disease in an 83-year-old man with a history of Agent Orange exposure who developed nephrotic syndrome resulting in diuretic-resistant anasarca. A subsequent bone marrow biopsy demonstrated a λ-restricted plasma cell population. The patient was initiated on hemodialysis and chemotherapy, resulting in clinical stabilization. This case report also contrasts AH amyloidosis with other forms of amyloidosis, emphasizing its unique clinical features, diagnostic challenges, and management considerations.

The International Society of Amyloidosis recognizes 15 types of kidney-related amyloidosis, with most studies identifying immunoglobulin light chain (AL) amyloidosis as the leading cause in over half of these cases. Heavy chain (AH) amyloidosis has been reported in 0.1-2.3% of kidney amyloidosis cases. This case is particularly novel due to the extremely rare occurrence of combined heavy and light chain (AHL) amyloidosis and its uncommon outcome. A 78-year-old man with hypertension and hyperlipidemia presented with swelling in both the upper and lower extremities, accompanied by dyspnea. On examination, he had crackles in both lung fields on auscultation. His abdomen was distended, and his upper and lower extremities were noted with + 3 edema. Workup revealed a serum creatinine of 1.25 mg/dL, and serum albumin of 2.7 g/dL, 22 g of proteinuria in a 24-hour collection, high lambda light chains at 3,800 mg/L with kappa/lambda ratio of 0.01, and elevated IgM levels at 3,500 mg/L. A kidney biopsy showed mesangial expansion with negative periodic-acid-Schiff and positive Congo Red Stain with apple-green birefringence under polarized light. Immunofluorescence revealed diffuse mesangial staining for IgM (3+), C3 (2+), and lambda light chains (2+). Mass spectrometry confirmed lambda light chain and mu heavy chain amyloidosis. The patient was diagnosed with AHL amyloidosis with a precursor low-grade B-cell lymphoma with plasmacytic differentiation. Based on these findings, rituximab and bendamustine were started. The patient's condition continued to deteriorate, ultimately progressing to dialysis dependance. Two months after starting dialysis, he chose to transition to hospice care. Kidney AHL amyloidosis is extremely rare. Diagnosis requires a kidney biopsy and mass spectrometry to identify the amyloidogenic protein, given the highest sensitivity and specificity of this technique and the limitations of immunofluorescence. Compared to AL, AHL patients have a higher prevalence of IgM monoclonal gammopathy, longer overall survival (5-year survival rate of 66%), and less advanced disease. Although data are limited, our case underscores the potential rapid progression to dialysis in kidney AHL amyloidosis patients with high proteinuria at diagnosis.

We performed a kidney biopsy on a 68-year-old man with 2.6 g/day proteinuria. Immunofluorescence (IF) study showed a positive finding of IgG (IgG1) along the glomerular capillary wall, suggesting membranous nephropathy. However, electron microscopy showed no subepithelial electron dense deposits and amorphous deposits of 8-12 nm fibrillar structure, and positive DFS/Congo red staining confirmed the diagnosis of amyloidosis. Amyloid deposits were localized only in the glomeruli. No overt extrarenal amyloid lesions were identified. Serum and urine were positive for monoclonal IgG-lambda, but IF was negative for kappa and lambda, ruling out AL-amyloidosis. At 75 years of age, he underwent a second kidney biopsy, and the IgG-positive findings at IF became more pronounced, with progressive glomerular sclerosing lesions. A proteomic analysis was performed focusing on the positive IgG finding in IF. The amyloid was proven to be composed of fragments of a heavy chain variable region sequence. AH-amyloidosis was the final diagnosis. He was treated according to the treatment for AL-amyloidosis, but hemodialysis was started at the age of 81, and died at the age of 86. We report a valuable case of AH-amyloidosis with an observed long-term prognosis.

Immunoglobulin heavy chain amyloidosis (AH amyloidosis) is an extremely rare subtype of immunoglobulin-derived amyloidosis and there is limited literature on how to diagnose and manage this disorder. We describe a rare case of AH amyloidosis with amyloid goitre and the importance of mass spectrometry in the identification of the different types of amyloids. While additional studies are needed, several observations suggest important practical implications, including differences in clinical picture, prognosis, and pathologic diagnosis. Immunoglobulin heavy chain amyloidosis is an extremely rare subtype of immunoglobulin-derived amyloidosis and amyloid goitre is even rarer.There is limited literature on how to diagnose and manage this disorder.This case portrays one of these cases - one of the few existing in the literature - and reinforces the diagnostic complexity of this entity.

Amyloidosis is a rare metabolic disorder primarily brought on by misfolding of an autologous protein, which causes its local or systemic deposition in an aberrant fibrillar form. It is quite rare for pulmonary tissue to be impacted by amyloidosis; of the three forms it can take when involving pulmonary tissue, nodular pulmonary amyloidosis is the most uncommon. Nodular pulmonary amyloidosis rarely induces clinical symptoms, and most often, it is discovered accidentally during an autopsy or via imaging techniques. Only one case of nodular pulmonary amyloidosis, which manifested as a spontaneous pneumothorax, was found in the literature. In terms of more precise subtyping, nodular amyloidosis is typically AL or mixed AL/AH type. No publications on AH-dominant type of nodular amyloidosis were found in the literature. We present a case of an 81 years-old male with nodular pulmonary AH-dominant type amyloidosis who presented with spontaneous pneumothorax. For a deeper understanding of the subject, this study also provides a review of the literature on cases with nodular pulmonary amyloidosis in relation to precise amyloid fibril subtyping. Since it is often a difficult process, accurate amyloid type identification is rarely accomplished. However, this information is very helpful for identifying the underlying disease process (if any) and outlining the subsequent diagnostic and treatment steps. Even so, it is crucial to be aware of this unit and make sure it is taken into consideration when making a differential diagnosis of pulmonary lesions.