BACKGROUND: Glomerulopathy with fibrillary deposits is not uncommon in routine nephropathology practice, with amyloidosis and fibrillary glomerulonephritis being the two most frequently encountered entities. Renal amyloid heavy and light chain (AHL) is relatively uncommon and its biopsy diagnosis is usually limited to cases that show strong equivalent staining for a single immunoglobulin (Ig) heavy chain and a single light chain, further supported by mass spectrometry (MS) and serum studies for monoclonal protein. But polyclonal light chain staining can pose a challenge.
METHODS: Herein we present a challenging case of renal AHL with polyclonal and polytypic Ig gamma (IgG) staining pattern by immunofluorescence. The patient is a 62-year-old Caucasian male who presented to an outside institution with a serum creatinine of up to 8.1 mg/dL and nephrotic range proteinuria. Despite the finding of a polyclonal and polytypic staining pattern on immunofluorescence, ultrastructural study of the renal biopsy demonstrated the presence of fibrils with a mean diameter of 10 nm. Congo red was positive while DNAJB9 was negative. MS suggested a diagnosis of amyloid AHL type with IgG and lambda, but kappa light chains were also present supporting the immunofluorescence staining results. Serum immunofixation studies demonstrated IgG lambda monoclonal spike. The patient was started on chemotherapy. The chronic renal injury however was quite advanced and he ended up needing dialysis shortly after.
CONCLUSIONS: Tissue diagnosis of AHL amyloid can be tricky. Thorough confirmation using other available diagnostic techniques is recommended in such cases.

Multiple myeloma is a disease of the plasma cells of the bone marrow, resulting in the proliferation and release of the monoclonal protein, which further causes end-organ damage. We report an unusual presentation of multiple myeloma, thereby insisting on the need for the treating physician to be aware of the various presentations that can be encountered in regular practice. It is often difficult to diagnose, and the diagnosis is usually made at a late stage of the disease. Even though uncurable, with recent advances, a proper regimen, newer chemotherapeutic agents, and stem cell transplantation, the disease can be brought into remission.

Adult-onset xanthogranuloma (AOX) is one of the four rare syndromes collectively referred to as adult xanthogranulomatous disease (AXD). It primarily occurs in the orbit and ocular adnexa and displays distinctive histopathological features, characterized by the infiltration of non-Langerhans-derived foam-like histiocytes and Touton giant cells. The presence of diffuse yellow plaques on the eyelids serves as a highly indicative feature. In this report, we present a compelling case of bilateral periorbital AOX. Initially, the patient received a diagnosis of necrotizing xanthogranuloma (NBX) and underwent treatment with dapsone, which yielded a poor response. Subsequently, through repeated biopsy, immunoprotein electrophoresis, and high-throughput sequencing, the diagnosis was revised to AOX. Subsequently, the patient\'s treatment was modified to include oral hormone therapy, and no further progression of the periorbital plaque was observed. Notably, the patient\'s sister was diagnosed with xanthelasma palpebrarum (XP), suggesting a potential genetic association between AOX and XP. Unfortunately, the sister declined further histologic examination and genetic sequencing of her skin lesions, impeding the acquisition of additional evidence regarding the genetic link between these two disorders. Despite the divergent pathological features, pathogenesis, and clinical presentation of AOX and xanthelasma palbrarum, clinicians should remain cognizant of the plausible genetic correlation between these two conditions and pursue further investigations when feasible.

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A 64-year-old security guard and longstanding known hypertensive presented with hypertensive heart disease (HHD), weight loss, an enlarged prostate, and a spontaneously fractured rib. Malignancy of the prostate with possible metastases to the ribs was strongly suspected. Biochemical profiling revealed a paraprotein. Other biochemical and hematological correlates that were on hand before serum protein electrophoresis were rather atypical. Paraprotein studies by immunofixation revealed IgA myelomatosis. Unlike previous reports from Caucasians there was normocalcaemia, normal protein level, microcytic hypochromia, low MCHC, cholesterol level at the lower limit of the reference range and normal urea level (in the face of markedly raised creatinine level). Nutritional modulation of the classical laboratory features of this disease may account for the fairly atypical laboratory picture.The need to appreciate the influence of nutritional status on the laboratory (especially biochemical) features of a disease and thus interpretation of diagnostic tests appears of exceptional current importance, given the widening gap in socioeconomic status and the level of poverty between the resource poor and developed countries from which the classical, clinical and laboratory features of most diseases were first described.This case report reminds of the need not only to recognize theoretically the impact of nutritional status on the laboratory characteristics of a disease but of the practical application of the nutritional perspective in the interpretation of diagnostic investigations, especially in nutritionally disadvantaged communities.