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Background Interferences on chemistry and immunoassay results due to paraproteinemia may lead to erroneous diagnoses and treatment. Such interferences are difficult to recognize and even more difficult to deal with. This report describes 1 such case where multiple measurands were affected and how the interferant was overcome. Case Report Paraproteins present in an immunoglobulin (Ig)G-lambda multiple myeloma specimen interfered with results of total bilirubin, direct bilirubin, inorganic phosphate, iron, ferritin, and total thyroxine measured on 3 platforms: AU5800, Alinity ci, and cobas pure. Repeat testing upon dilution with normal saline or deproteinization by polyethylene glycol precipitation gave unsatisfactory results on some or all the affected measurands. Repeat testing after dilution of the interferant serum with a healthy serum corrected the anomalous results for all the affected measurands. Conclusion Dilution of paraproteinemic serum with a healthy serum of known concentrations appears to be the most suitable method to negate the effects of paraproteinemic interferences. [ABSTRACT FROM AUTHOR]

Heavy-chain deposition disease (HCDD) is a rare disorder characterized by the deposition of monoclonal immunoglobulin. Due to the disease's rarity and diagnostic challenges, its prognosis is generally poor. Herein, we report a case of successful treatment of HCDD coexisting with multiple myeloma. A 56-year-old man presented at an outpatient clinic with complaints of whole-body pain, edema, and dyspnea that had persisted for 2 weeks. Diagnostic tests confirmed nephrotic syndrome, hematuria, and progressive renal failure. Serum immunofixation electrophoresis identified the presence of IgG kappa paraprotein. A diagnosis of multiple myeloma was established following a bone marrow biopsy. A renal biopsy revealed antibodies specific to the heavy chains of IgG on immunofluorescence, and electron microscopy showed diffuse electron-dense "powdery" densities in the glomerular basement membrane. Based on these findings, the patient was diagnosed with both HCDD and multiple myeloma. Following the diagnosis, the patient immediately began anti-plasma cell therapy using bortezomib, lenalidomide, and dexamethasone. Intermittent hemodialysis was initiated due to persistent azotemia during the diagnostic process; however, renal function improved significantly after only 1 month of therapy, allowing the discontinuation of dialysis. Early intervention with anti-plasma cell therapy, such as bortezomib, is known to improve prognosis in the early stages of the disease. This case report is presented to enhance understanding of HCDD and underscore the importance of prompt diagnosis and treatment in managing this rare condition.

Background: POEMS syndrome is a debilitating paraneoplastic disorder associated with plasma cell neoplasia. Clinically, it is characterized by predominantly demyelinating peripheral neuropathy that often starts in the pelvic limbs, organomegaly, endocrinopathy, skin changes, and elevated serum M protein. Diagnosis requires meeting a set of clinical criteria in which polyradiculoneuropathy and plasma cell disorder are the two mandatory criteria. The aim of this article is to describe 3 clinical cases, their diagnostic approach, and therapeutic management. Clinical cases: In this study, three clinical cases with features compatible with POEMS syndrome are presented. Nerve conduction studies revealed demyelinating involvement with sensory-motor impairment, and evidence of a monoclonal spike was found. Treatment was successful in two cases and partially effective in one, although the latter was associated with delayed diagnosis. Conclusion: Despite significant advancements in understanding the pathophysiology and treatment of this disease, diagnosis remains challenging, especially in locations lacking the necessary resources for accurate diagnosis. It is essential to emphasize that it requires a multidisciplinary approach. The prognosis of this disease is closely linked to early diagnosis. Here, we describe three cases from a reference center in Mexico to increase awareness of the disease›s diagnosis. [ABSTRACT FROM AUTHOR]

Herein, we report the case of primary amyloidosis with multi-organ involvement in a female patient in her 50s. The patient had a history of relapsing polychondritis, chronic kidney disease, and monoclonal gammopathy of undetermined significance (MGUS). The clinical manifestations included neuropathic pain, sensorimotor polyneuropathy, intrahepatic cholestatic liver injury, gastrointestinal symptoms, dysautonomia, and myocardial thickening. Initial histologic evaluations of the abdominal fat pad aspirate and bone marrow biopsy were negative for amyloid deposition. However, due to a high index of suspicion, a second bone marrow biopsy was performed, confirming the presence of the amyloid protein. Given the patient's complex medical history, other types of amyloidosis, such as AA amyloidosis, AL amyloidosis, and ß2-microglobulin amyloidosis, should also be considered as differential diagnoses. The type of amyloid protein was subsequently identified through laser microdissection of amyloid fibrils followed by liquid chromatography–tandem mass spectrometry as AL-lambda (amyloid light-chain) amyloidosis. The patient presented unfavorable evolution, with progressive dysautonomia, being admitted to the ICU, culminating in refractory circulatory shock, and undergoing an empirical broad-spectrum antibiotic therapy. After a few days, she presented pulseless ventricular tachycardia, culminating in her death, before undergoing specific treatment. This article highlights the crucial role of precise identification in guiding appropriate therapeutic strategies for this complex, yet potentially severe, diseases.