Acute tubulointerstitial nephritis associated with antineutrophil cytoplasmic antibody following cimetidine treatment: a case report.

BACKGROUND: Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis usually induces rapidly progressive glomerulonephritis, including pauci-immune necrotizing crescentic glomerulonephritis. Acute tubulointerstitial nephritis (ATIN), which is often drug-induced, is a frequent cause of kidney injury. However, ATIN associated with ANCA without any glomerular lesions has been rarely reported, and drug-induced ATIN associated with ANCA is not well recognized. Here we present a case of an older woman with ATIN associated with myeloperoxidase-ANCA (MPO-ANCA) following cimetidine treatment. CASE PRESENTATION: A 70-year-old woman was admitted to our hospital due to acute kidney injury and mild proteinuria. She had a one-year history of chronic thyroiditis and dyslipidemia, for which she was taking levothyroxine sodium and atorvastatin, respectively. Two weeks before admission she had started cimetidine, methylmethionine sulfonium chloride, and itopride hydrochloride for gastric discomfort persistent since a month. She had experienced fatigue for two weeks and later appetite loss. The patient demonstrated a positive titer for MPO-ANCA (192 IU/mL) and a positive drug-induced lymphocyte stimulation test for cimetidine. She underwent two kidney biopsies that revealed ATIN without any glomerular lesions. Despite discontinuation of cimetidine on admission, renal injury continued with the presence of high MPO-ANCA titer. Oral steroid treatment was closely related with the recovery of her renal function and disappearance of MPO-ANCA. CONCLUSIONS: In this case, ATIN presented as sustained renal insufficiency and high MPO-ANCA titer despite withdrawal of cimetidine. Therefore, we reason that the development of ANCA-associated ATIN was caused by cimetidine. Serologic follow-up with measurement of MPO-ANCA titers and renal biopsy are recommended when the clinical history is inconsistent with the relatively benign course of drug-induced ATIN.

Acantholytic squamous cell carcinoma of the lung with marked lymphogenous metastases and high titers of myeloperoxidase-antineutrophil cytoplasmic antibodies: a case report.

BACKGROUND: Acantholytic squamous cell carcinoma (ASQCC), histologically characterized by intercellular bridge loosening, is recognized as a rare variant of squamous cell carcinoma (SQCC). ASQCC may demonstrate a worse prognosis than conventional SQCC. Pulmonary ASQCC is particularly rare; its biological behavior and prognostic data have not been reported. CASE PRESENTATION: We report the clinical and autopsy findings of a 71-year-old Japanese man with pulmonary ASQCC. Pulmonary lesions, suggestive of idiopathic interstitial pneumonia, were radiologically observed 3 and 6 years prior to the patient's most recent hospitalization; however, the patient did not undergo further medical examinations. Upon being discovered unconscious, the patient was admitted to our hospital. Dehydration and lower limb muscle weakness were noted, as were laboratory findings of coagulation abnormalities and renal dysfunction. Computed tomography helped confirm a 21-mm peripheral nodule in the upper left lobe of the lung, with associated swollen lymph nodes in the bilateral hilar, mediastinal, and para-aortic regions. Brain and spinal lesions, suggestive of neurological disturbances, were not found. Small cell lung carcinoma was suspected, upon admission, but high serum levels of squamous cell carcinoma antigen and cytokeratin-19 fragments were present. Therefore, advanced lung cancer, possibly SQCC, was diagnosed. The patient was treated with best supportive therapy, and died one month after admission. Hypercalcemia and high serum levels of parathyroid hormone-related protein (PTHrP) and myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA) titers were observed. Progressive renal insufficiency was absent due to improved renal function subsequent to hydration. An autopsy helped confirm the left lung tumor as an ASQCC associated with pulmonary lymphangitic carcinomatosis and multiple metastases in the lungs and lymph nodes. Skin lesions suggesting malignant tumors were absent. The metastatic lesions consisted largely of acantholytic tumor cells, and the lungs showed usual interstitial pneumonia pattern; vasculitis was absent. CONCLUSIONS: This is the first reported case of pulmonary ASQCC resulting in an aggressive clinical course, with marked lymphogenous metastases and PTHrP-associated hypercalcemia. The high serum MPO-ANCA titers were clinicopathologically insignificant, but may have been related to the pulmonary interstitial lesion. Pulmonary ASQCC represents a highly malignant subset of lung cancer.

Presence of Citrullinated Histone H3-Positive Neutrophils in Microscopic Polyangiitis from the Early Phase: An Autopsy Proven Case.

A 76-year-old man was admitted with general fatigue, weight loss, fever, headache, renal failure, and a high serum level of myeloperoxidase-antineutrophil cytoplasmic antibody. Biopsy revealed citrullinated histone H3 (citH3)-positive neutrophils adherent to the temporal artery endothelium. Three days after completing pulse steroid therapy, he suffered from a sudden disturbance of consciousness and died. On autopsy, the kidneys showed the most severe vasculitis with dense infiltration of citH3-positive neutrophils. The lungs showed intra-alveolar hemorrhage due to capillaritis. Severe brain hemorrhage was found in the left frontal lobe and putamen with uncal herniation. No vasculitis or thrombi was observed in the brain. The right dura mater was thickened due to fibrosis and inflammation. In conclusion, autopsy revealed systemic vasculitis with infiltration of abundant citH3-positive neutrophils, suggesting that the neutrophil extracellular trap formation and citH3 might play important roles in the early phases and development of microscopic polyangiitis.

Avacopan's potential to decrease MPO-ANCA titres concurrent with ameliorated activity in ANCA-associated vasculitis.

Avacopan, an orally administered C5a receptor antagonist, is effective in microscopic polyangiitis via the inhibition of neutrophil priming induced by C5a. However, the exact effect of avacopan on the production of myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA) is yet to be clearly established. This report presents a microscopic polyangiitis patient without major organ damage where high levels of MPO-ANCA persisted with high-dose steroid therapy and azathioprine, but the addition of avacopan led to a reduction in MPO-ANCA titres. The present case implies that avacopan-mediated inhibition of C5a may lead to a reduction in MPO-ANCA levels, thereby potentially ameliorating the pathophysiology of ANCA-associated vasculitis. Nevertheless, the impact of avacopan on MPO-ANCA production cannot be asserted solely based on this report; therefore, further examination is necessary through subgroup analysis using data from larger-scale studies.

Latent class analysis of chest CT abnormalities to define subphenotypes in patients with MPO-ANCA-positive microscopic polyangiitis.

BACKGROUND: Patients with microscopic polyangiitis (MPA) and positive myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA) may present with various abnormalities in chest computed tomography (CT). This study aimed to identify subphenotypes using latent class analysis (LCA) and to explore the relationship between the subphenotypes and clinical patterns, as well as compare the clinical characteristics of these subphenotypes in patients with MPO-ANCA-positive MPA (MPO-MPA). METHODS: The study identified subphenotypes using LCA based on chest CT findings in 178 patients with MPO-MPA and pulmonary involvement from June 2014 to August 2022. RESULTS: LCA identified 27 participants (15.2%) in class 1, 43 (24.1%) in class 2, 35 (19.7%) in class 3, and 73 (41.0%) in class 4. Class 1 was characterized by prominent inflammatory exudation, class 2 by fibrosis and architectural distortion, class 3 by predominantly bronchiectasis, and class 4 by lesions mixed with inflammation and fibrosis. Class 1 had the highest level of extrapulmonary disease activity, with 77.8% of patients experiencing diffuse alveolar hemorrhage. Class 2 had the lowest level of extrapulmonary disease activity, with 41.9% of patients showing usual interstitial pneumonia. Class 3 patients were more likely to have complications involving the ear, nose, and throat, as well as pulmonary infections before treatment, and they exhibited the best outcomes. The characteristics and outcomes of class 4 were intermediate among the four classes. CONCLUSIONS: These findings suggest that bronchiectasis may represent a unique pattern of pulmonary involvement in MPO-MPA, highlighting the importance of screening for bronchiectasis in MPO-MPA and identifying optimal management strategies.

Antineutrophil cytoplasmic antibody-associated vasculitis predominantly manifesting tubulointerstitial nephritis: A case report.

The common histopathology of antineutrophil cytoplasmic antibody-associated vasculitis comprises pauci-immune crescentic glomerulonephritis with concomitant tubulointerstitial nephritis. Tubulointerstitial nephritis in the absence of glomerular involvement in patients with antineutrophil cytoplasmic antibody-associated vasculitis is uncommon. We report a case of antineutrophil cytoplasmic antibody-associated vasculitis-associated acute kidney injury manifesting as tubulointerstitial nephritis without glomerulonephritis. A 75-year-old woman with fever, cough, and myalgia developed kidney dysfunction with inflammatory reactions and tubular-type proteinuria, without glomerular hematuria. A kidney biopsy revealed tubulointerstitial nephritis with arteritis. We ruled out important underlying etiologies of tubulointerstitial nephritis, including infection, drug reactions, and autoimmune diseases. Since chest high-resolution computed tomography demonstrated mild interstitial pneumonia in bilateral lower lung fields, myeloperoxidase antineutrophil cytoplasmic antibody was measured and found to be positive. Therefore, we diagnosed the patient with antineutrophil cytoplasmic antibody-associated vasculitis-associated tubulointerstitial nephritis but not glomerulonephritis, and interstitial pneumonia. The patient's kidney function and symptoms markedly improved with prednisolone treatment. Clinicians should maintain high-level vigilance for antineutrophil cytoplasmic antibody-associated vasculitis as a possible underlying component of tubulointerstitial nephritis, particularly when kidney function deteriorates with tubulointerstitial injuries without glomerular features.

Anti-Inflammatory and/or Anti-Fibrotic Treatment of MPO-ANCA-Positive Interstitial Lung Disease: A Short Review.

The presence of a lung lesion is common in microscopic polyangiitis (MPA), and interstitial lung disease (ILD) can lead to a poor prognosis. Although myeloperoxidase antineutrophil cytoplasmic antibodies (MPO-ANCA) are often present in patients with MPA, patients with ILD and MPO-ANCA positivity but without other manifestations of systemic vasculitis have also been reported. Therefore, the possible association between MPO-ANCA, MPA, and idiopathic ILD remains unclear. This problematic matter has influenced the treatment strategy of MPO-ANCA-positive ILD patients without systemic vasculitis. Clinicians should undertake treatment with careful consideration of the four major causes of death in MPO-ANCA-positive ILD: acute exacerbation of ILD, progressive lung fibrosis, infectious comorbidities, and diffuse alveolar hemorrhage. Further, clinicians need to carefully judge whether inflammation or fibrosis is the dominant condition with reference to the patient's clinical domain and radiopathological lung features. Recently, anti-fibrotic agents such as nintedanib and pirfenidone were shown to be effective in treating various etiologies associated with ILD and have thus led to the widening of treatment options. In this review, the clinical characteristics, radiopathology, prognosis, and therapeutic options in patients with MPO-ANCA-positive ILD are summarized using limited information from previous studies.

Myeloperoxidase-antineutrophil cytoplasmic antibody-associated diffuse alveolar hemorrhage caused by denosumab.

Denosumab is a bone anti-resorptive drug, commonly used for treating osteoporosis. Pulmonary involvement has rarely been reported as a possible serious adverse effect of this medication. Herein, we report the case of a 67-year-old woman who presented with non-massive hemoptysis, anemia, and extensive pulmonary opacities on a chest radiograph for 3 days after receiving denosumab. The patient was diagnosed with myeloperoxidase-antineutrophil cytoplasmic antibody-associated pulmonary hemorrhage secondary from denosumab. She was treated with high doses of intravenous methylprednisolone and cyclophosphamide combined with plasmapheresis. Subsequently, her clinical and radiological findings improved without residual abnormalities after treatment.

Spontaneously regressed granulomatosis with polyangiitis: A case report.

A 71-year-old woman presented with chest pain, cough, and back pain. A chest roentgenogram showed multiple nodular shadows in both lungs. She was diagnosed with granulomatosis with polyangiitis (GPA). The multiple nodular shadows in both lungs regressed spontaneously in a few months. There are few reports of spontaneous regression of GPA, and the underlying mechanism is unclear. Neutrophil extracellular traps (NETs) have been recently shown to be involved in GPA. NETs may also be related to the natural regression of GPA.

Optic neuropathy secondary to granulomatosis with polyangiitis in a patient with Graves' disease: a case report.

BACKGROUND: Dysthyroid optic neuropathy is the most commonly suspected diagnosis of optic neuropathy in Graves' patients; however, other causes need to be ruled out. We present a unique case of optic neuropathy secondary to hypertrophic pachymeningitis with antineutrophil cytoplasmic antibody-associated vasculitis, which was suspected to be antithyroid drug related. CASE PRESENTATION: A 79-year-old Japanese male presented with acute visual loss in the left eye. He had a 24-year history of Graves' disease and was taking methimazole. Best-corrected visual acuity was 0.8 in the right eye and light perception in the left eye, and relative afferent pupillary defect in the left eye was seen. Ocular movement was normal, and there were no findings explaining visual loss in intermediate optic media and fundus in the left eye. Contrast-enhanced magnetic resonance imaging demonstrated thickened dura mater. Tests for myeloperoxidase-antineutrophil cytoplasmic antibody, proteinuria, and hematuria were positive; pulmonary nodule lesions and a blood clot in the left lower leg were also found. After excluding the presence of diseases that could lead to hypertrophic pachymeningitis, we diagnosed optic neuropathy due to hypertrophic pachymeningitis with granulomatosis with polyangiitis-a subtype of antineutrophil cytoplasmic antibody-associated vasculitis. Since he had history of using methimazole, antineutrophil cytoplasmic antibody-associated vasculitis was considered as drug related. We started high-dosage steroid pulse therapy followed by 1 mg/kg body weight daily of oral prednisolone, and subsequently tapered. Methimazole was stopped. Best-corrected visual acuity recovered to 0.9, 2 weeks after starting treatment. Though myeloperoxidase-antineutrophil cytoplasmic antibody remained negative, the symptom relapsed 6 months after treatment initiation. We gave a second high-dose steroid pulse therapy followed by prednisolone tapered together with methotrexate. Remission remained, and using 4 mg/week methotrexate without prednisolone, myeloperoxidase-antineutrophil cytoplasmic antibody was kept within the normal limit until now, 4 years after onset. CONCLUSION: We present a case of optic neuropathy with hypertrophic pachymeningitis related to antineutrophil cytoplasmic antibody-associated vasculitis, which was suspected to be drug related. The patient had good visual recovery after quitting the drug and receiving immunosuppressive therapy with systemic steroids. Hypertrophic pachymeningitis with antineutrophil cytoplasmic antibody-associated vasculitis related to antithyroid drugs should be considered as a differential diagnosis for optic neuropathy in Graves' patients in whom optic nerve compression is not obvious.

IgG4-related hypothalamo-hypophysitis.

•A patient exhibited IgG4-related hypothalamo-hypophysitis.•Prominent high-signal areas of swelling were observed in the hypothalamus, tuber cinereum, infundibulum, and bilateral optic nerve systems.•MRI T1WI with contrast media demonstrated enhanced neurohypophysis and cystic swelling, and compressed anterior pituitary.•MRI findings improved rapidly after 4 days of steroid therapy.

The development of rapidly progressive glomerulonephritis associated with both antineutrophil cytoplasmic antibody-associated vasculitis and anti-glomerular basement membrane nephritis in the course of nontuberculous mycobacterium infection: a case report.

BACKGROUND: Antineutrophil cytoplasmic antibodies (ANCA) and Anti-glomerular basement membrane (GBM) antibodies often induce rapidly progressive glomerulonephritis (RPGN). Some reports have demonstrated RPGN with the sequential appearance of ANCA then anti-GBM antibodies, suggesting that ANCA may induce the development of anti-GBM antibodies. Whereas, many reports have shown that the development of ANCA is associated with various infectious diseases, such as non-tuberculous mycobacterial infection. CASE PRESENTATION: A 65-year-old woman with pulmonary non-tuberculous mycobacterial (NTM) infection was monitored without treatment. One year later, serum myeloperoxidase (MPO)- ANCA were elevated (14.1 U/mL (normal value < 3.0 U/ml)). A high fever and RPGN appeared 1 year later, and serum MPO-ANCAs were 94.1 U/mL. Anti-GBM antibodies were also detected. A renal biopsy revealed crescentic glomerulonephritis with linear deposits of IgG and C3c along the GBM and interstitial inflammation with endarteritis of arterioles. The diagnosis was RPGN associated with anti-GBM nephritis and ANCA-associated vasculitis. CONCLUSION: This report shows that preceding NTM infection may have induced ANCA and anti-GBM antibodies and caused the development of RPGN.

Combined pulmonary fibrosis and emphysema with myeloperoxidase-antineutrophil cytoplasmic antibody positivity that resolved upon smoking cessation.

Myeloperoxidase antineutrophil cytoplasmic autoantibody (MPO-ANCA) is well-known as a serological marker for small-vessel vasculitis. However, when a smoker with interstitial lung disease (ILD) exhibits serum ANCA positivity without systemic vasculitis, diagnosis is a matter of debate; the relationship between smoking and ANCA is unknown. We report a case of combined pulmonary fibrosis and emphysema (CPFE) with elevated MPO-ANCA. Surgical lung biopsy showed emphysema and fibrotic interstitial pneumonia without vasculitis. The MPO-ANCA level decreased after smoking cessation, and no vasculitis or progression was observed during 3 years of follow-up. This suggested that smoking cessation was related to normalization of MPO-ANCA and corresponding disease activity.

The Sequential Development of Antiglomerular Basement Membrane Nephritis and Myeloperoxidase-antineutrophil Cytoplasmic Antibody-associated Vasculitis.

A 55-year-old woman presented with deafness, increased levels of myeloperoxidase (MPO)-antineutrophil cytoplasmic antibody (ANCA), and renal insufficiency with proteinuria and hematuria. Renal biopsy revealed crescentic glomerulonephritis with the linear deposition of immunoglobulin G along the glomerular basement membrane (GBM) and peritubular capillaritis. The anti-GBM antibody levels on admission and 10 days after admission were 11.7 U/mL and 127 U/mL, respectively. These results indicated the sequential development of anti-GBM nephritis and MPO-ANCA-associated vasculitis. This report shows that anti-GBM nephritis may be caused by MPO-ANCA-associated vasculitis because of preceding otitis media, the sequential anti-GBM antibody titers, and the findings of peritubular capillaritis.

Aortic Aneurysm as a Complication of Myeloperoxidase-antineutrophil Cytoplasmic Antibody-associated Vasculitis.

Myeloperoxidase-antineutrophil cytoplasmic antibody-associated vasculitis (MPO-AAV) does not usually involve large vessels, such as the aorta. However, we experienced three cases having an aortic aneurysm as a complication of MPO-AAV with renal insufficiency. In one patient it involved the onset of descending aortic dissection during treatment for MPO-AAV; another two patients had an abdominal aortic aneurysm at the time of our diagnosis of MPO-AAV. Although we found no pathological evidence in our patients, MPO-AAV might result in large vessel inflammation. Therefore, we suggest that patients with MPO-AAV should be examined by computed tomography scan to check for the presence of an aortic aneurysm.

Development of intracerebral hemorrhage in the short-term clinical course of a patient with microscopic polyangiitis without neurological symptoms at diagnosis: an autopsy case.

A 77-year-old man with high-grade fever, progressive renal dysfunction, high serum level of C-reactive protein and positive serum myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) was diagnosed with microscopic polyangiitis with rapidly progressive glomerulonephritis, and remission induction treatment with glucocorticoids and intravenous cyclophosphamide was initiated. Although his general condition improved in a short time, intracerebral hemorrhage occurred 12 days after the initiation of treatment and emergent hematoma evacuation was performed. However, he passed away on day 14. Surprisingly, even though no clinical findings for any organs except for renal involvement was detected before his death, autopsy revealed necrotizing vasculitis affecting various systemic organs including kidney, pancreas, liver, myocardium in ventricle, adipose tissue of the left adrenal gland, small intestine, gallbladder, bronchus, prostate, testis and spleen. It is difficult to detect widespread vasculitis without clinical symptoms and signs in patients with ANCA-associated vasculitis. A whole body assessment tool is necessary to detect unexpected vital organ damage, including cerebral vessels.

Successful Treatment of Dual-Positive Anti-Myeloperoxidase and Anti-Glomerular Basement Membrane Antibody Vasculitis with Pulmonary-Renal Syndrome.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis and anti-glomerular basement membrane (GBM) disease are two separate diseases, while sometimes they can coexist together. The exact mechanisms are not clear, but due to the rapid progression and poor prognosis, prompt and aggressive treatment is usually required. We treated with steroids combined with cyclophosphamide and rituximab an 84-year-old man with ANCA-associated vasculitis and anti-GBM disease who had prior pulmonary fibrosis and a coexisting anterosuperior mediastinal mass. Conventional therapy including steroids, plasmapheresis and cyclophosphamide failed to attenuate the anti-GBM disease, yet he responded to an alternative treatment of rituximab. This case suggests the efficacy of steroids and immunosuppressant for the treatment of a dual-positive case with an anterosuperior mediastinal mass.