Mixed connective tissue disease (MCTD) is a rheumatologic overlap syndrome that can present with symptoms of systemic lupus erythematous, scleroderma, and polymyositis. A severe but rare complication that can occur in MCTD is scleroderma renal crisis. With multiple poor prognostic indicators, the renal outcome is usually poor. The clinical and histological picture is one of a thrombotic microangiopathy. Clinical suspicion has to be high for additional thrombotic or autoimmune processes coexisting due to associated morbidity. In this article, we report a rare case of scleroderma renal crisis in a patient with MCTD who we treated with plasma exchange for clinical suspicion for an underlying thrombotic thrombocytopenia and mycophenolate mofetil for MCTD. The patient had multiple poor prognostic indicators yet made a full renal recovery in less than 3 months.

Multiple myeloma (MM) is a clonal proliferation of antibody-producing plasma cells that can precipitate renal injury through multiple mechanisms. Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is an inflammatory condition that can result in renal failure through mononuclear cell infiltration and consequent destruction of glomeruli. Several case reports have identified clinical situations where differentiating these entities has been challenging. Renal biopsy is an invaluable tool in differentiating between MM and AAV when clinical uncertainty exists. We report the case of an 85-year-old man who presented with a rapid decline in renal function and serologies positive for both MM and AAV. Renal biopsy findings confirmed the diagnosis of myeloma kidney and excluded vasculitis. This case highlights an unusual clinical scenario in which both proteinase-3 (PR-3) and myeloperoxidase (MPO) antibodies are positive. While these antibodies are both individually associated with ANCA vasculitis, they are seldom simultaneously positive. Our case would suggest that positive PR-3 and MPO antibodies should raise concern for an alternative diagnosis. Indeed, ANCA, PR-3, and MPO antibodies can all be positive in patients with monoclonal gammopathy in the absence of vasculitis. Our case underscores the value of renal biopsy in the setting of MM.

Systemic sclerosis (SSc) is a rare autoimmune disorder that is typically divided into limited cutaneous systemic sclerosis and diffuse cutaneous systemic sclerosis. Scleroderma renal crisis (SRC) is a severe complication of SSc and typically presents with new-onset hypertension and a reduction in renal functioning. In patients presenting with typical features of SRC, treatment with an angiotensin-converting enzyme inhibitor along with dialysis as needed is typically initiated empirically. Renal biopsy is not recommended in patients with SSc presenting with typical features of SRC. Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a rare co-occurrence with SSc, in around 2.5% to 9% of patients. AAV is an inflammatory condition that can result in renal failure due to mononuclear cell infiltration and destruction of blood vessels. Treatment of AAV is drastically different from SRC and typically consists of immunosuppressants and dialysis if needed. SRC and AAV can only reliably be distinguished by renal biopsy. We present a rare case of a 70-year-old female with limited cutaneous systemic sclerosis who presented to the emergency department with new-onset renal failure. Her serology was found to be positive for antinuclear antibodies and myeloperoxidase antibodies, resulting in a renal biopsy, which revealed an acute necrotizing vasculitis consistent with AAV. We suggest consideration of a renal biopsy in patients with SSc who present with new-onset renal failure, especially with nonresponse to SRC treatment or positive serology.

Pulmonary embolism (PE) represents a prevalent cause of morbidity and mortality in the United States, with approximately 600 000 cases diagnosed annually. The mortality rate for untreated PE is as high as 30%. Right ventricular (RV) dysfunction is a sign of possible adverse outcomes with right-sided heart failure being the usual cause of death from PE. There is a spectrum of clinical presentations associated with PE diagnoses, from incidental and asymptomatic to rapid hemodynamic collapse. Despite successes in identifying patients with “high-risk” PEs for aggressive thrombolytic interventions and “low-risk” PEs for outpatient anticoagulation, a significant lack of consensus exists regarding intervention modalities for PEs identified as “intermediate risk” or “submassive,” defined as normotensive (systolic blood pressure ≥90 mm Hg) with acute RV dysfunction and myocardial injury. In this case series, we review the management and outcomes of 2 patients with submassive PEs and sustained tachycardia in the setting of normal blood pressures, and we address the need to recognize tachycardia as an ominous RV compensatory sign, indicative of impending hemodynamic collapse, that should lead to aggressive therapy with vascular intervention.

Minimal change disease (MCD) accounts for 10-15% of idiopathic nephrotic syndrome in adults. Patients typically present with nephrotic range proteinuria, hypertension, microscopic hematuria and can even progress to acute renal failure. MCD can be primary (idiopathic) or secondary from etiologies such as cancer, medications, autoimmune conditions and infections. The link between infectious etiologies for MCD is important to recognize, since MCD tends to show a good response to treatment of the underlying cause. Influenza A has been reported as a secondary cause of MCD and rarely, influenza A, not B, can also present with liver failure. We present an atypical case of a 60-year-old female with no past medical history who presented with liver failure along with acute kidney injury and nephrotic range proteinuria.