Study of the radiologic features of Legionnaires' disease with mediastinal adenopathy: Legionella or lymphoma?

An index case of Legionnaires's disease with mediastinal adenopathy prompted us to review our recent experience with Legionnaires' disease to determine the incidence of mediastinal adenopathy of this finding in Legionnaires' disease. We reviewed the radiographic findings of 90 hospitalized adults with Legionnaires' disease from 2015 to 2017. Excluded were 11 patients with mediastinal adenopathy due to non-Legionnaires' disease causes, e.g., lymphoma. Thirty-seven of the remaining patients had both chest films and chest computed tomography (CT) scans. Of the 37 Legionnaires' disease cases, 13/37 (35%) had mediastinal adenopathy and 8/27 (24%) also had unilateral hilar adenopathy. These chest CT findings were not seen on chest films. Chest CT scans are needed to detect mediastinal adenopathy in Legionnaires' disease. Mediastinal adenopathy may be due to Legionnaires' disease or a malignancy. Some findings in Legionnaires' disease are also present in mediastinal adenopathy due to lymphomas, e.g., highly elevated erythrocyte sedimentation rate (ESR), lactate dehydrogenase (LDH), and ferritin. Hospitalized adults with Legionnaires' disease and mediastinal adenopathy should have serial chest CT scans to monitor resolution of the mediastinal adenopathy. In hospitalized adults with otherwise unexplained persistent mediastinal adenopathy, they should be considered as being due to another etiology, e.g., lymphoma, until proven otherwise.

Lessons learned from splenic infarcts with fever of unknown origin (FUO): culture-negative endocarditis (CNE) or malignancy?

Culture negative endocarditis (CNE) is a common concern in patients with fever, heart murmur, cardiac vegetation, and negative blood cultures. The diagnosis of CNE is not based only on negative blood cultures and a cardiac vegetation. The clinical definition of CNE is based on negative blood cultures plus the findings of culture positive infective endocarditis (IE), e.g., fever, cardiac vegetation, splenomegaly, peripheral manifestations. Because embolic splenic infarcts may occur with culture positive IE, some may assume that splenic infarcts are a sign of CNE. Previously, CNE was due to fastidious and non-culturable organisms. With current diagnostic methods, fastidious organisms grow in 2-3 days. Therefore, fastidious IE are a subset of culture positive IE, but do not represent true CNE. We describe a case of an elderly female who presented with a fever of unknown origin (FUO) and multiple splenic infarcts thought by some to represent CNE. An extensive workup for CNE pathogens was negative. The final cause of her splenic infarcts was a diffuse large B-cell lymphoma (DLBCL). Review of the literature, as well as this case, confirms that splenic infarcts are not a feature of CNE. In patients with fever, splenic infarcts, and negative blood cultures, physicians should search for an alternate explanation rather than CNE, e.g., malignancy and hypercoaguable state (lupus anticoagulant).

An Unusual Case of Serologically Confirmed Post-Partum Lyme Disease Following an Asymptomatic Borrelia burgdorferi Infection Acquired during Pregnancy and Lacking Vertical Transmission in Utero.

In this report, we describe a 23-year-old female who, while pregnant, was exposed to Borrelia burgdorferi but did not develop significant signs or symptoms (joint pain, arthritis) of Lyme disease until shortly after delivering a healthy child at term. Serologic testing confirmed infection with B. burgdorferi. A 3-week course of treatment with doxycycline was completely curative. There was no evidence for congenital or perinatal transmission of this pathogen at any point pre-term or postnatally. The key reasons that could account for this unique clinical scenario are discussed in the context of previously published related reports.