Dengue viral infection with unusual presentations has been described in literature, but autopsy is rarely done and is only limited to some cases, based on the literature review. Here, we present the autopsy findings in three cases of dengue encephalitis. All the three patients clinically presented with signs of meningoencephalitis and were positive for dengue non-structural (NS) 1 antigen (Ag) in the serum and cerebrospinal fluid. The postmortem findings revealed cerebral edema, inflammation, hemorrhage, and microinfarcts in all the three cases with herniation of the brain in one case. Sub-massive hepatocellular necrosis was seen in one case. The renal findings included hemorrhage into the Bowman's capsule with red cell cast in two of three cases. The pulmonary findings included a diffuse destruction of the alveoli and hemorrhage into the alveolar spaces in all the three cases.

The hallmark of vasculitis is autoimmune inflammation of blood vessels and surrounding tissues, resulting in an array of constitutional symptoms and organ damage. The lung is commonly targeted in the more familiar ANCA-associated small vessel vasculitidies, but large and medium vessel vasculitides, including Takayasu arteritis, giant cell arteritis, polyarteritis nodosa, Behcet's disease, and necrotizing sarcoid granulomatosis, may also feature prominent pulmonary involvement. Pulmonary manifestations of these conditions include pulmonary arterial aneurysms, pulmonary hypertension, diffuse alveolar hemorrhage, pulmonary nodules, and parenchymal infiltrates. An understanding of the diverse manifestations of vasculitis and a high index of clinical suspicion are essential to avoid delays in disease recognition that may result in permanent or life threatening morbidity. In this review, we outline the general clinical manifestations, pulmonary manifestations, diagnostic workup, imaging findings, and treatment of medium, large, and variable vessel vasculitides.

Systemic vasculitides frequently affect the pulmonary vasculature. As the signs and symptoms of pulmonary vasculitis are variable and nonspecific, diagnosis and treatment represent a real challenge. Vasculitides should be given consideration, as these diseases present severe manifestations of rapidly progressing pulmonary disease. Examining other organs usually affected by vasculitides (e.g., the skin and kidneys) and determining autoantibody levels are essential to a better management of the disease. A radiological study would also contribute to establishing a diagnosis. The lungs are commonly involved in small-vessel vasculitis, anti-glomerular basement membrane disease, and vasculitides associated with antineutrophil cytoplasmic antibodies. Associated life-threatening diffuse alveolar haemorrhages and irreversible damage to other organs-usually the kidneys-are severe complications that require early diagnosis. Vasculitides are rare diseases that affect multiple organs. An increasing number of treatments-including biological agent-based therapies-requiring cooperation between specialists and centers have become available in the recent years. In the same way, clinicians should be familiar with the complications associated with immunosuppressive therapies.

Defined by the accumulation of red blood cells into the alveolar space, diffuse alveolar hemorrhage (DAH) is a severe and potentially fatal medical condition requiring careful attention. In contrast to simple extravasation of erythrocytes facilitated by impaired hemostasis or hemodynamic causes, DAH in vasculitis is due to capillaritis, that is, inflammation of capillaries. Dyspnea, hemoptysis, chest infiltrates, and abrupt fall of blood hemoglobin level represent the cardinal features of DAH; yet, hemoptysis is lacking in one-third of cases. Bronchoalveolar lavage, retrieving bright red fluid, is the best diagnostic clue, also excluding infection and other causes of hemoptysis. Although not recommended, lung biopsy is the gold standard for the diagnosis of DAH and pulmonary capillaritis. Pulmonary capillaritis may be primary as in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis or secondary to drugs (especially antithyroid drugs such as propylthiouracil), infections, connective tissue diseases especially systemic lupus erythematosus, or other small vessel vasculitides. Newer toxic causes of drugs of abuse may be difficult to diagnose. Granulomatosis with polyangiitis and microscopic polyangiitis are the most common causes of capillaritis and DAH, whereas DAH is extremely rare in eosinophilic granulomatosis with polyangiitis. When pulmonary capillaritis is not secondary to underlying systemic vasculitis, idiopathic pauci-immune pulmonary capillaritis may be considered, with or without ANCA. Supportive treatment strategy is mandatory in all cases of DAH. Mechanical ventilation and extracorporeal membrane oxygenation may be used in severe cases. Early identification and removal of the putative drug is crucial in drug-induced vasculitis/DAH and may obviate the need for immunosuppressive therapy. High-dose corticosteroids, intravenous cyclophosphamide, and recently rituximab are the mainstay of treatment in vasculitis. Plasma exchange is recommended in anti-glomerular basement membrane disease and in severe DAH associated with systemic lupus erythematosus and is used in selected cases in ANCA-associated vasculitis.

Microscopic polyangiitis (MPA) is one of the main clinical presentations of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides. Although the disease is defined by clinical and pathological criteria, the anti-myeloperoxidase (MPO) specificity of ANCAs is observed in almost 80% of MPA patients. The direct pathogenic role of anti-MPO antibodies has been proven in animal models, in which the disease was transmitted by transfer of anti-MPO antibodies or anti-MPO-specific splenocytes. The most frequently affected organs in this disease are the kidneys and the lungs. Necrotizing and crescentic glomerulonephritis can be revealed by rapidly progressive renal failure, but kidney injury can be more slowly progressive and lead to end-stage renal disease without major extrarenal manifestations. The most frequent pulmonary manifestation is diffuse alveolar hemorrhage, but some patients may present with chronic interstitial fibrosis leading to respiratory failure. General signs such as fever and weight loss, muscular and articular symptoms, peripheral neuropathy, and cutaneous involvement may also reveal the disease. Although the relapse rate is quite low after induction of remission, 5-year mortality is 25%, with even higher mortality rates in older patients (> 65 years old), or those with significant kidney dysfunction. Iatrogenic causes (particularly infections) are an important cause of deaths in these vulnerable patients. Future studies are warranted to determine the optimal maintenance immunosuppressive regimen to minimize side effects of immunosuppression.