Congophilic fibrils in the glomeruli with polyclonal immunoglobulin gamma staining - another cause for diagnostic overlap: A case report.

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. CASE SUMMARY: 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. CONCLUSION: Tissue diagnosis of AHL amyloid can be tricky. Thorough confirmation using other available diagnostic techniques is recommended in such cases.

Coronary artery myointimal dysplasia in patients with pheochromocytoma-possible causal relationship: pathophysiology and clinical implication with reference to Takotsubo cardiomyopathy and spontaneous coronary dissection.

Myocardial damage in catecholamine cardiomyopathy, characterized by patchy myocyte necrosis commonly with contraction band appearances, interstitial fibrosis, and varying degrees of inflammatory infiltrates, has been well documented. However, coronary vascular pathology has not been recognized. Autopsy of a 43-year-old housewife who died of acute apical anteroseptal myocardial infarction revealed the incidental finding of a left adrenal pheochromocytoma. The epicardial and intramyocardial median- and small-sized coronary arteries exhibited myointimal dysplasia in the form of fibroblastic proliferation in the intima and media, resulting in thickened dysplastic vessels with marked luminal narrowing, occasionally leading to near-total occlusion. The distal left anterior descending artery showed features of recanalization after prior embolic occlusion. The density and severity of vascular involvement revealed a decreasing gradient from apical to basal region, mainly affecting the left ventricle, but the proximal coronary arteries were minimally affected. Myointimal dysplasia was not seen in control cases of hypertensive heart, and despite its presence in hearts with hypertrophic cardiomyopathy, it lacked the distinctive pattern of distribution and the epicardial vessels are uninvolved. Myointimal dysplasia probably results from reactive fibroplasia in response to the vasoconstrictive effect of circulating or local neurosecretory catecholamine and appears crucial in the pathogenesis of various types of catecholamine cardiomyopathy, including Takotsubo or stress cardiomyopathy. Together with the direct catecholamine cardiotoxicity, they result in diffuse microscopic ischemic necrosis and fibrosis. Depending on the type of catecholamine overproduction and action, together with the characteristic anatomic distribution and density of the various types of adrenergic receptors in the ventricles, different regions of the heart are variously affected so that different patterns of ventricular dysfunction are produced, with the subsequent angiographic appearances ranging from apical through midventricular to basal ballooning. Additional complications from the myointimal dysplasia include spontaneous coronary dissection, acute myocardial infarction, and superimposed thrombus formation in the dysplastic vessels and dyskinetic ventricle, with the risk of further damage from embolic events.

Denervation pseudohypertrophy of calf muscles associated with diabetic neuropathy.

Denervation of muscle usually leads to muscle atrophy with fatty replacement but, uncommonly, also results in muscle hypertrophy or pseudohypertrophy with fatty replacement. We report the ultrasonographic and magnetic resonance imaging (MRI) findings of a patient with diffuse fatty infiltration of calf muscles as a result of denervation pseudohypertrophy. The elevated fasting glucose, neurogenic electromyographic changes, and muscle atrophy with adipose tissue infiltration are consistent with diabetic neuropathy as the cause of denervation pseudohypertrophy. Lumbosacral radiculopathy and plexopathy were excluded by MRI. The imaging features reported in the literature are reviewed. The important differential diagnosis of infiltrating lipoma and denervation hypertrophy, as well as other causes of monomelic hypertrophy or swelling, is discussed. This case report demonstrates the importance of MRI, with clinical, biochemical, electrophysiological, and histologic correlation in the diagnosis of denervation pseudohypertrophy. Correct diagnosis of denervation pseudohypertrophy has an important role in guiding further investigations and treatment of the disease and the underlying cause.